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Chapter 4
Nosocomial Infection Prevention and Control
Infection control is one of the most important functions a nurse can perform. The
nurse becomes the client’s advocate by understanding the infectious process and
practicing infection control principals. In addition, the nurse can ensure personal
safety by using common sense with all clients.
Clients entering a variety of health care settings are at risk for infections related
to numerous diagnostic and invasive procedures. Furthermore, many clients have a
lower resistance to microorganisms and develop disease or infection after increased
exposure. The nurse helps to protect clients from infections by controlling and/or
eliminating sources. Clients and families must be able to recognize sources of
infections and be able to initiate protective measures. The nurse should instruct them
about the nature of infections, the mode of transmission, the reasons for susceptibility,
and the measure of control. Previous studies have shown that the duration of
hospitalization are proportional to the rate of nosocomial infections, that organ
transplantation and the use of monitoring apparatus increase nosocomial infections
which in turn increase the cost of hospitalization, delay the clients’ recovery from
diseases and threaten the lives of the clients. With the introduction of new infections
such as HIV and the recurrence of old infections such as tuberculosis, the nurse must
practice infection control and barrier protection. This chapter will emphasize
techniques for personal safety.
Section 1 Basic Knowledge about Nosocimial Infection
Concepts
Infection. The transmission of microorganisms into a host after evading or
overcoming defense mechanisms, resulting in the organism’s proliferation and
invasion within host tissue(s). Host responses to infection may include clinical
symptoms or may be subclinical, with manifestations of disease mediated by direct
organisms pathogenesis and/or a function of cell-mediated or antibody responses that
result in the destruction of host tissues. If the infectious disease can be transmitted
directly from one person to another, it is a communicable or contagious disease.
Nosocomial infection. A term that is derived from two Greek words “nosos”
(disease) and “komeion” (to take care of).
In its broad meaning, nosocomial infection is defined as any infection or disease
that any individual suffers from the invasion of pathogens in hospital.
In its narrow meaning, nosocomial infection refers to any infection or disease
which does not exist or is not in incubation period when the clients are hospitalized,
but is caused by the invasion of disease-producing microorganisms in hospital with
the manifestation of the symptoms during the clients’ hospitalization or after
discharge from hospital.
The term nosocomial infection is retained to refer only to infections acquired in
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hospitals.
Healthcare-associated infection (HAI). An infection that develops in a patient who
is cared for in any setting where healthcare is delivered (e.g., acute care hospital,
chronic care facility, ambulatory clinic, dialysis center, surgicenter, home) and is
related to receiving health care (i.e., was not incubating or present at the time
healthcare was provided). In ambulatory and home settings, HAI would apply to any
infection that is associated with a medical or surgical intervention. Since the
geographic location of infection acquisition is often uncertain, the preferred term is
considered to be healthcare-associated rather than healthcare-acquired.
Classification of nosocomial infection
According to the site of infections, nosocomial infection has the possibility to
occur in every system and every site.
According to the source of the pathogens, nosocomial infections can be classified
into two types: endogenous and exogenous infections. Endogenous infections, also
called autogenous infections, can occur when part of the client’s flora becomes
altered and an overgrowth results. When sufficient numbers of microorganisms
normally found in one body cavity or lining are transferred to another body site, an
endogenous infection develops. For example, transmission of enterococci, normally
found in fecal material, from hands to the skin is a cause of wound infections.
Exogenous infections, also called cross infections, are the results of the invasion of
causative microorganisms from the source other than the clients’ themselves, such as
from hospital personnel, the other clients, various objects and hospital environment.
According to the pathogenic organisms, nosocomial infections can be caused by
bacteria, viruses, fungi, mycoplasma，chlamydia，protozoa, etc. The most common
pathogenic organisms are bacteria.
Risks for Nosocomial Infection
Host resistance decline and impaired immune defenses
Physiologic factors
Infants have immature immune systems. Children acquire more immunity but are
susceptible to infectious diseases such as mumps and measles. Young and middle-age
adults have refined body system defenses and immunity. Old adults’ immune
responses decline, and the structure and function of major organs change. Extremes of
age can increase susceptibility to infection.
Pathologic factors
Underlying disease (e.g. diabetes), human immunodeficiency virus/acquired
immune deficiency syndrome [HIV/AIDS], malignancy, and transplants can increase
susceptibility to infection as do a variety of medications that alter the normal flora
(e.g., antimicrobial agents, gastric acid suppressants, corticosteroids, antirejection
drugs, antineoplastic agents, and immunosuppressive drugs). Surgical procedures and
radiation therapy impair defenses of the skin and other involved organ systems.
Psychological factors
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Increased stress elevates cortisone levels, causing decreased resistance to
infection. Hosts in good spirits can increase resistance and decrease the risk of
infection.
Numerous invasive procedures
Indwelling devices such as urinary catheters, endotracheal tubes, central venous
and arterial catheters and synthetic implants facilitate development of nosocomial
infection by allowing potential pathogens to bypass local defenses that would
ordinarily impede their invasion and by providing surfaces for development of
bioflims that may facilitate adherence of microorganisms and protect from
antimicrobial activity. Some infections associated with invasive procedures result
from transmission within the healthcare facility; others arise from the patient’s
endogenous flora.
Antibiotics abuse
The widespread routine use of antibiotics, especially on a single-injection basis
after surgery, could be a causative factor in the increase of antibiotic-resistant
organisms. Antibiotic resistance comes mainly because of inappropriate or improper
use of antibiotics by physicians.
Ineffective administrative management
The infection control regulations are not established in some hospitals. Some
hospitals do not put the established regulations into practice. Hospital leaders and
staff do not realize the importance of infection control. They are reluctant to put
resources, energy and time in controlling nosocomial infection. All above factors
increase the risk of infection.
Chain of Infection
The presence of a pathogen does not mean that an infection will begin.
Development of an infection occurs in a cyclical process that depends on three
fundamental elements: a source (or reservoir) of infectious agents, a susceptible host
with a portal of entry receptive to the agent, and a mode of transmission for the agent.
Infection develops if this chain stays intact. The nurse’s efforts to control infection are
directed at breaking this chain.
Sources of infectious agents
Infectious agents transmitted during healthcare derive primarily from human
sources but inanimate environmental sources also are implicated in transmission.
Human reservoirs include patients, healthcare personnel, and household members and
other visitors. Such source individuals may have active infections, may be in the
asymptomatic and/or incubation period of an infectious disease, or may be transiently
or chronically colonized with pathogenic microorganisms, particularly in the
respiratory and gastrointestinal tracts. The endogenous flora of patients (e.g., bacteria
residing in the respiratory or gastrointestinal tract) also are the source of infections. In
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health care setting, environment, equipment and apparatus, such as mops, rest room,
ventilation apparatus and oxygen equipment, can be easily contaminated by pathogens
and become the reservoirs of pathogens.
Modes of transmission
A mode of transmission is the route and way by which microorganisms are
spread from a source of infection to a susceptible host. The modes of transmission
vary by type of organism and some infectious agents may be transmitted by more than
one route: some are transmitted primarily by direct or indirect contact, (e.g., Herpes
simplex virus [HSV], respiratory syncytial virus, Staphylococcus aureus), others by
the droplet, (e.g., influenza virus, B. pertussis) or airborne routes (e.g., M.
tuberculosis). Other infectious agents, such as bloodborne viruses (e.g., hepatitis B
and C viruses [HBV, HCV] and HIV are transmitted rarely in healthcare settings, via
percutaneous or mucous membrane exposure. Importantly, not all infectious agents
are transmitted from person to person. The three principal routes of transmission are
summarized below.
Contact transmission
The most common mode of transmission, contact transmission is divided into
two subgroups: direct contact and indirect contact.
Direct contact transmission Direct transmission occurs when microorganisms are
transferred from one infected person to another person without a contaminated
intermediate object or person.
Indirect contact transmission Indirect transmission involves the transfer of an
infectious agent through a contaminated intermediate object or person. In the absence
of a point-source outbreak, it is difficult to determine how indirect transmission
occurs. However, extensive evidence suggests that the contaminated hands of
healthcare personnel are important contributors to indirect contact transmission.
Examples of opportunities for indirect contact transmission include:
• Hands of healthcare personnel may transmit pathogens after touching an
infected or colonized body site on one patient or a contaminated inanimate
object, if hand hygiene is not performed before touching another patient.
• Patient-care devices (e.g., electronic thermometers, glucose monitoring devices)
may transmit pathogens if devices contaminated with blood or body fluids are
shared between patients without cleaning and disinfecting between patients.
• Shared toys may become a vehicle for transmitting respiratory viruses (e.g.,
respiratory syncytial virus) or pathogenic bacteria (e.g., Pseudomonas
aeruginosa) among pediatric patients.
• Instruments that are inadequately cleaned between patients before disinfection
or sterilization (e.g., endoscopes or surgical instruments) or that have
manufacturing defects that interfere with the effectiveness of reprocessing
may transmit bacterial and viral pathogens.
Droplet transmission
Droplet transmission is, technically, a form of contact transmission, and some
infectious agents transmitted by the droplet route also may be transmitted by the
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direct and indirect contact routes. However, in contrast to contact transmission,
respiratory droplets carrying infectious pathogens transmit infection when they travel
directly from the respiratory tract of the infectious individual to susceptible mucosal
surfaces of the recipient, generally over short distances, necessitating facial protection.
Respiratory droplets are generated when an infected person coughs, sneezes, or talks,
or during procedures such as suctioning, endotracheal intubation, cough induction by
chest physiotherapy and cardiopulmonary resuscitation. Evidence for droplet
transmission comes from epidemiological studies of disease outbreaks, experimental
studies and from information on aerosol dynamics. Studies have shown that the nasal
mucosa, conjunctivae and less frequently the mouth, are susceptible portals of entry
for respiratory viruses. The maximum distance for droplet transmission is currently
unresolved, although pathogens transmitted by the droplet route have not been
transmitted through the air over long distances, in contrast to the airborne pathogens
discussed below. Historically, the area of defined risk has been a distance of <3 feet
（1feet=30.48cm）around the patient and is based on epidemiologic and simulated
studies of selected infections. Using this distance for donning masks has been
effective in preventing transmission of infectious agents via the droplet route.
However, experimental studies with smallpox and investigations during the
global SARS outbreaks of 2003 suggest that droplets from patients with these two
infections could reach persons located 6 feet or more from their source. It is likely that
the distance droplets travel depends on the velocity and mechanism by which
respiratory droplets are propelled from the source, the density of respiratory secretions,
environmental factors such as temperature and humidity, and the ability of the
pathogen to maintain infectivity over that distance. Thus, a distance of <3 feet around
the patient is best viewed as an example of what is meant by “a short distance from a
patient” and should not be used as the sole criterion for deciding when a mask should
be donned to protect from droplet exposure. Based on these considerations, it may be
prudent to don a mask when within 6 to 10 feet of the patient or upon entry into the
patient’s room, especially when exposure to emerging or highly virulent pathogens is
likely. More studies are needed to improve understanding of droplet transmission
under various circumstances.
Airborne transmission
Airborne transmission occurs by dissemination of either airborne droplet nuclei
or small particles in the respirable size range containing infectious agents that remain
infective over time and distance (e.g., spores of Aspergillus spp, and Mycobacterium
tuberculosis). Microorganisms carried in this manner may be dispersed over long
distances by air currents and may be inhaled by susceptible individuals who have not
had face-to-face contact with (or been in the same room with) the infectious
individual. Preventing the spread of pathogens that are transmitted by the airborne
route requires the use of special air handling and ventilation systems to contain and
then safely remove the infectious agent. Infectious agents to which this applies
include Mycobacterium tuberculosis, rubeola virus (measles), and varicella-zoster
virus (chickenpox).
Other sources of infection
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Transmission of infection from sources other than infectious individuals include
those associated with common environmental sources or vehicles (e.g. contaminated
food, water, blood, or medications (e.g. intravenous fluids). Vectorborne transmission
of infectious agents from mosquitoes, flies, rats, and other vermin also can occur in
healthcare settings.
Susceptible hosts
Infection is the result of a complex interrelationship between a potential host and
an infectious agent. Most of the factors that influence infection and the occurrence
and severity of disease are related to the host. However, characteristics of the
host-agent interaction as it relates to pathogenicity, virulence and antigenicity are also
important, as are the infectious dose, mechanisms of disease production and route of
exposure. There is a spectrum of possible outcomes following exposure to an
infectious agent. Some persons exposed to pathogenic microorganisms never develop
symptomatic disease while others become severely ill and even die. Some individuals
are prone to becoming transiently or permanently colonized but remain asymptomatic.
Still others progress from colonization to symptomatic disease either immediately
following exposure, or after a period of asymptomatic colonization. The immune state
at the time of exposure to an infectious agent, interaction between pathogens, and
virulence factors intrinsic to the agent are important predictors of an individuals’
outcome.
Factors affecting susceptibility include ①age, gender, race and heredity; ②
normal immune defenses (good physiological, psychological status ); ③underlying
disease and medical therapy; ④nutritional status; ⑤social life; ⑥mental health; ⑦
stress, et al.
Susceptible hosts in hospital mainly include: ①younger children and old adults;
②severely impaired immune defenses; ③malnutrition; ④receiving various immune
suppressed treatment; ⑤long-term use of antibiotics; ⑥receiving numerous invasive
procedures; ⑦long operation time; ⑧extended length of hospitalization; ⑨not in
good spirits, lack of active cooperation.
Section 2 Cleaning, Disinfection and Sterilization
Concepts
Cleaning. Cleaning is a process, usually involving detergent or enzymatic presoak
that removes foreign material (e.g. dirt or microorganisms) from an object. It is often
used to clean furniture, floor, dishware, and so on, or to prepare the objects for
disinfection or sterilization. Cleaning is the most essential step in reprocessing
instruments and equipment.
Disinfection. Disinfection is a process that eliminates almost all pathogenic
organisms on objects, with exception of bacterial spores, to make the number of them
decreased to a harmless degree.
Disinfectant. A disinfectant is a chemical agent that destroys most pathogens but may
not kill bacterial spores. Chemical disinfection should only be used if heat treatment is
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impractical or if it may cause damage to the equipment. There is a broad spectrum of
chemical disinfectants that have different antimicrobial activities. Most of them do not
necessarily kill all microorganisms or spores that are present on an inanimate object
but instead reduce the number of microorganisms to a level that is not harmful to
health. Disinfectants are used on inanimate objects only and not on living tissue.
Chemicals used to kill microorganisms on skin or living tissue are known as
antiseptics.
The broad category of disinfection may be subdivided into high-level,
intermediate-level, and low-level disinfection according to the anti-microbial activity
of the disinfectant (see Table 7-1).
Low level disinfectant (LLD): LLD is an agent that destroys all vegetative bacteria
(except tubercle bacilli), lipid viruses, some nonlipid viruses, and some fungus, but
not bacterial spores.
Intermediate-level disinfectant (ILD): ILD is an agent that destroys all vegetative
bacteria, including tubercle bacilli, lipid enveloped and some nonlipid enveloped
viruses, and fungus spores, but not bacterial spores.
High-level disinfectant (HLD): A high-level disinfectant is a chemical or physical
agent or process that is capable of killing some bacterial spores when used in
sufficient concentration, temperature, and under suitable conditions. It is therefore
expected to be effective against vegetative bacteria, fungi, viruses and other
microorganisms. It does not kill high numbers of bacterial spores.
Table 7-1 Classification of Disinfectants
Level
HLD
ILD
LLD
Vegetative
﹢
﹢
﹢
Bacteria
Tubercle bacilli
﹢
﹢
﹣
Spores
﹢
﹣
﹣
Fungi
﹢
﹢
±
Viruses
Lipid
Nonlipid
﹢
﹢
﹢
±
﹢
±
Sterilization. Sterilization is a process that destroys all forms of microorganisms,
including bacterial spores by either physical or chemical methods. The sterilized
objects are called aseptic supplies. Sterilization is accomplished principally by steam
under pressure, by dry heat, and by chemical sterilants.
Sterilant. Sterilant refers to an agent that destroys all viable forms of microbial life to
achieve sterilization.
The Instrument Processing (Decontamination Steps)
There are two steps to processing items that are used during clinical and surgical
procedures. Cleaning is the first and the most important step. Cleaning is followed by
either sterilization or disinfection and by immediate use or proper storage of the item
(see Figure 7-2).
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Figure 7-2: Decontamination Steps
Risks of Infection from Equipment
The risks of infection from equipment may be classified into three categories.
Placing instruments and equipment into one of the following categories can be helpful
in choosing the proper level of disinfection or sterilization needed in order to protect
the patients and the health care personnel.
High risk (critical items)
High risk items are items that penetrate sterile tissues such as body cavities and
the vascular system. These items are called critical items because of the high risk of
infection if such an item is contaminated with any microorganism before penetrating
the tissue. Cleaning followed by sterilization is required. High-level disinfection may
sometimes be appropriate if sterilization is not possible, e.g., flexible endoscopes.
Examples of high-risk items include surgical instruments, intra-uterine devices,
vascular catheters, implants, etc.
Intermediate risk (semi-critical items)
Semi-critical items are items that do not penetrate the skin or enter sterile areas
of the body but that are in close contact with mucous membranes or with non-intact
skin. Reprocessing semi-critical items involves meticulous cleaning followed by, at a
minimum, high level disinfection. Examples include respiratory equipment, flexible
endoscopes, laryngoscopes, specula, endotracheal tubes, thermometers, and other
similar instruments.
Low risk (noncritical items)
Noncritical items are items that come into contact with normal and intact skin
(but not mucous membranes) as stethoscopes or with the inanimate environment (e.g.
walls, floors, ceilings, furniture, sinks, etc.). Reprocessing of noncritical items
involves cleaning and may also require low level disinfection (e.g. blood pressure
cuffs, stethoscopes).
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Common Methods
Single Use Items
These items may be used in critical, semi-critical, or noncritical areas; however,
they are single use items that are prepackaged with the appropriate level of
disinfection or sterilization and are disposed of after a single use. Examples include
gloves, needles, and syringes. The figure below shows the relationship between types
of items and the sterilization or disinfection that they must undergo (see Figure 7-3).
Figure 7-3: Relation between type of item & its decontamination
Cleaning
Cleaning is the removal of all foreign material (dirt and organic matter) from the
object being reprocessed. Two key components of cleaning are friction to remove
foreign matter and fluids to remove or rinse away contamination. Thorough cleaning
will remove most organisms from a surface and should always precede disinfection
and sterilization procedures. If instruments and other items have not been cleaned,
sterilization and disinfection may not be effective because microorganisms trapped in
organic material may survive sterilization or disinfection. Cleaning is normally
accomplished by the use of water, detergents and mechanical actions. Detergent is
essential to dissolve proteins and oil that can reside on instruments and equipment
after use.
Cleaning may be manual or mechanical. Mechanical cleaning includes ultrasonic
cleaners or washer/disinfectors that may facilitate cleaning and decontamination of
some items and may reduce the need for handling. The solution used most often to
clean is an enzymatic presoak (protease formula that dissolves protein). Alternatively
a detergent can be used. Detergents lower surface tension and lift dirt or oil away
from the device.
Mechanical Cleaning
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Most modern sterilization units are automated and there is minimal handling of
dirty equipment by staff. The equipment is placed in trays ready for washing:
•Washer-disinfectors are strongly recommended for medical equipment/devices
that can withstand mechanical cleaning, to achieve the required exposure for
cleaning and to reduce potential risk to personnel. Manufacturer’s instructions
must be followed for the use and regular maintenance, cleaning and calibration
of the washer-disinfector. Washer-disinfectors may be used for low level
disinfection.
• Ultrasonic washers are strongly recommended for any semi-critical or critical
medical equipment/device that has joints, crevices, lumens or other areas that
are difficult to clean. Manufacturer’s instructions must be followed for use of
the ultrasonic cleaner. The ultrasonic washing solution should be changed at
least daily or more frequently if it becomes visibly soiled.
Manual Cleaning
All items requiring disinfection or sterilization should be dismantled before
cleaning. Cold water is preferred; it will remove most of the protein materials (blood,
sputum, etc.) that would be coagulated by heat and would subsequently be difficult to
remove. The most simple, cost-effective method is to thoroughly brush the item while
keeping the brush below the surface of the water in order to prevent the release of
aerosols. The brush should be decontaminated after use and should be dried. Finally,
items should be rinsed in clean water and then should be dried. Items are then ready
for use (noncritical items) or for disinfection (semi-critical items) or for sterilization
(critical items).
Manual cleaning is necessary when:
• Mechanical cleaning facilities are not available;
• Delicate instruments have to be cleaned;
• Complex instruments need to be taken apart to be cleaned;
• Items with narrow lumens need to be cleaned (endoscopes).
Remember when cleaning:
• Always wear utility gloves, a mask, and eye protection when cleaning
instruments.
• Disassemble instruments and other items with multiple parts, and be sure to
brush in the grooves, teeth, and joints to items where organic material can
collect and stick.
• Rinse items thoroughly with clean water to remove all detergent. Any detergent
left on the items can reduce the effectiveness of further processing.
• Allow items to air dry or dry them with a clean towel if chemical disinfection is
going to be used. This is to avoid diluting the chemical solutions used after
cleaning.
Sterilization
The choice of the method for sterilization depends on a number of factors
including the type of material that the object to be sterilized is made of, the number
and type of microorganisms involved, the classification of the item, and availability of
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sterilization methods.
Sterilization is principally accomplished by:
• Steam under pressure
• Dry heat
• Chemical sterilants
I. Steam under Pressure (Autoclaving)
Steam sterilization is the most common and most preferred method employed for
sterilization of all items that penetrate the skin and mucosa if they are heat stable. The
temperatures required for steam sterilization are lower than those for dry heat
sterilization because moist heat under pressure allows for more efficient destruction of
microorganisms.
Advantages:
• Highly effective;
• Rapid heating and rapid penetration of instruments;
• Nontoxic;
• Inexpensive;
• Can be used to sterilize liquids.
Disadvantages:
• Items must be heat and moisture resistant;
• Will not sterilize powders, ointments or oils.
• Needs good maintenance.
Types of steam sterilizers
a. Gravity downward-displacement sterilizers
• The chamber fills with steam, displacing the air downward and forcing it out of
the drain valve.
• Holding temperature: 121ºC for 20-30 minutes.
b. High-speed prevacuum sterilizers
• Similar to downward-displacement sterilizers, with the addition of a vacuum
pump system.
• Vacuum pump removes the air from the chamber before the steam is admitted,
reducing the penetration time and total cycle time.
• Holding temperature 132ºC for 5-10 minutes.
Notes:
• Clean all items to be sterilized.
• Open or unlock all hinged items and disassemble items with multiple parts.
• Arrange all labeled packs, or unwrapped items in the chamber of the autoclave
in a way that allows the steam to circulate freely. Do not stack.
• Do not begin timing until the autoclave reaches the desired temperature and
pressure. Sterilization time does not include the time it takes to reach the
required temperature or the time for exhaust and drying; therefore, it is shorter
than the total cycle time.
• Follow the manufacturer instruction for operating the autoclave.
• Use sterile pick-ups to handle unwrapped items from the autoclave. The packs
of equipment should come out of the autoclave dry. Wet packs must be
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considered non-sterile. Do not store packs or unwrapped items until they cool to
room temperature. This may take several hours.
• Label accurately with contents, date of processing and expiration date and store
wrapped materials in storage cabinet.
II. Dry heat sterilization (Hot Air Oven):
Dry heat is preferred for reusable glass, metal instruments, oil, ointments and
powders. Do not use this method of sterilization for other items, which may melt or
burn. Dry heat ovens should have fans to give even temperature distribution and faster
equilibrium of load to sterilization temperatures. Dry heat sterilization must be rigidly
monitored with each cycle due to differences in penetration with different items.
Temperature and exposure times vary, depending on article being sterilized. Generally,
holding temperature and sterilization time is 160 ºC, 2 hours; 170 ºC, 1 hour; 180 ºC,
0.5 hour.
Advantages:
• Can be used for powders, anhydrous oils, creams and glass.
• Reaches surfaces of instruments that cannot be disassembled.
• No corrosive or rusting effect on instruments.
• Low cost.
Disadvantages:
• Penetrates materials slowly and unevenly.
• Long exposure time’s necessary.
• High temperatures damage rubber goods and some fabrics.
• Limited package materials.
Notes:
• Clean and dry all items to be sterilized.
• Do not begin timing until the oven reaches the holding temperature.
• Package materials generally no more than 10cm×10cm×20cm.
III. Chemical Sterilants
Before deciding to use a chemical sterilant, consider whether a more appropriate
method is available. Chemical sterilants are primarily used for heat- labile equipment
where single use is not cost effective. Instruments and other items can be sterilized by
soaking in a chemical solution followed by rinsing in sterile water. The immersion
time to achieve sterilization or sporicidal activity is specific for each type of chemical
sterilant. The difficulty lies in the fact that immersion for the appropriate time, rinsing
with sterile water, and then transferring the device to a sterile field for use is
challenging. Also, in contrast with steam sterilization methods, a biological indicator
is not available for most chemical sterilants. Given these limitations most liquid
chemical sterilants are instead used for high-level disinfection. If an item is sterilized
chemically, it should be used immediately after sterilization, to be sure that it is
sterile.
① Ethylene oxide gas
Uses:
Ethylene oxide can be used to sterilize most articles that can withstand
temperatures of 50-60 °C. However, it should be used under carefully controlled
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conditions because it is extremely toxic and explosive. Although it is very versatile
and can be used for heat-labile equipment, fluids, and rubber, etc., a long period of
aeration (to remove all traces of the gas) is required before the equipment can be
distributed. The operating cycle ranges from 2-24 hours and it is a relatively
expensive process. Sterilization with ethylene oxide should be monitored by using
bacterial spore tests.
Advantages:
• Not harmful to heat sensitive and lensed instruments
Disadvantages:
• Toxic to humans
• Requires monitoring of residual gas levels in environment
•
• Lengthy cycle required to achieve sterilization and aeration
• Highly flammable and explosive and highly reactive with other chemicals
• Causes structural damage to some medical equipment/devices
② Glutaraldehyde
Uses:
A 2% glutaraldehyde solution for at least 10 hours can be used to sterilize heat
cement. Sterilized equipment/devices must be rinsed with sterile water to remove all
residual chemical. Sterilized equipment/devices must be handled in a manner that
prevents contamination from process through storage to use. Product is time limited
following activation, usually maximum 14 days. During reuse, the concentration may
drop as dilution of the product occurs. Chemical test strips are available for
determining whether an effective concentration of active ingredients is present in
despite of repeated use and dilution.
Advantages:
• Heat sensitive equipment/devices
• Does not coagulate protein
Disadvantages:
•
• Need proper ventilation and in containers with close-fitting lids
• Handling provides opportunities for contamination
• Requires copious rinsing with sterile water
• Unable to monitor sterility
• Lengthy process
• Shelf life of 14 days once mixed
• During reuse, the concentration may drop as dilution of the product occurs
Precautions:
Glutaraldehyde is an eye and nasal irritant and may cause respiratory illness
(asthma) and allergic dermatitis. Glutaraldehyde should not be used in an area with
little or no ventilation. Eye protection, a plastic apron, and gloves must be worn when
glutaraldehyde liquid is made up, disposed of, and used for sterilization. Latex gloves
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may be worn and discarded after use if the duration of contact with glutaraldehyde is
brief, e.g. less than 5 minutes. For longer duration, nitrile gloves must be worn.
③ Peracetic acid
Uses:
Peracetic acid can be used to sterilize heat-labile items (e.g. arthroscopes, dental
instruments). In vapour form, peracetic acid is volatile, has a pungent odour, is toxic
and is a fire and explosion hazard.
Advantages:
•
• Leaves no residue
• Effective in presence of organic matter
• Sporicidal at low temperatures
Disadvantages:
•
• Corrosive
• Material incompatibility with some materials
• Unstable particularly when diluted
④ Formaldehyde
Advantages:
• Active in the presence of organic materials
Disadvantages:
• Toxic
• Carcinogenic
• Strong irritant
• Pungent odour
• Cannot be monitored for sterility
Monitoring the Effectiveness of Sterilization
To ensure that sterilization has been successful, the process of sterilization (and
not the end product) is tested. Indicators have been developed to monitor the
effectiveness of sterilization by measuring various aspects of the process through
different indicators.
Mechanical indicators
These indicators, which are part of the autoclave or dry-heat oven itself, record
and allow you to observe time, temperature, and/or pressure readings during the
sterilization cycle.
Chemical indicators
Each pack must have external chemical indicators. In addition, it is
recommended that both internal and external visible chemical indicators be used to
detect penetration into the pack. An internal chemical indicator shall be placed inside
all packages. This indicator shall be placed in the area of the package least accessible
to steam or to the sterilizing agent in order to verify that the sterilant has penetrated
the package.
• Tape with lines that change color when the intended temperature has been
reached.
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• Pellets in glass tubes that melt, indicating that the intended temperature and time
have been reached.
• Indicator strips that show that the intended combination of temperature, time, and
pressure has been achieved.
• Indicator strips that show that the chemicals and/or gas are still effective.
• Chemical indicators are available for testing ethylene oxide, dry heat, and steam
processes.
Biological indicators
These indicators use heat-resistant bacterial endospores to demonstrate whether
or not sterilization has been achieved e.g. spore-laden strips or vials. If the bacterial
endospores have been killed after sterilization, you can assume that all
microorganisms have been killed as well. After the sterilization process the strips are
placed in a broth that supports aerobic growth and incubated for 2-7 days. The
advantage of this method is that it directly measures the effectiveness of sterilization.
The disadvantage is that this indicator is not immediate, as are mechanical and
chemical indicators. Bacterial culture results are needed before sterilization
effectiveness can be determined.
The recommended test microorganisms are:
• Geobacillus stearothermophilus spores for sterilizers that use steam or peracetic
acid;
• Bacillus atrophaeus spores for sterilizers that use dry heat or ethylene oxide.
Disinfection
I. High Level Disinfection (HLD)
When sterilization is not available, HLD is the only acceptable alternative for
instruments and other items that will come into contact with the bloodstream or
tissues under the skin. There are five types of HLD:
• Disinfection by boiling
• Ultraviolet Light Radiation
• Microwave Oven
• Chemical disinfection
① Boiling
High-level disinfection is best achieved by moist heat such as boiling in water,
which kills all organisms except for a few bacterial spores. It is suitable for the
disinfection of objects which is resistant to moisture and high temperature, such as
mental, glass, rubber, et al. It is important to note that boiling equipment items in
water will not achieve sterilization.
Notes:
• Clean all items to be high-level disinfected.
• Open all hinged instruments and other items and disassemble those with
multiple parts. Place bowls and containers upright so they fill with water.
Make sure that all items are completely submerged because water must touch
all surfaces for HLD to be achieved.
• Once the water is in a rolling boil, start timing for 5-15 minute. Use a timer or
45
make sure to record when the boiling begins. From this point on do not add or
remove any water or items.
• Lower the heat to keep the water at a gentle, rolling boil. Too vigorous boiling
may damage items and will speed the evaporation of the water.
• Remove items using dry, high-level disinfected pickups. Place items to air-dry
on a high-level disinfected tray or on a high-level disinfected container that is
away from dust and insects and in a low-traffic area. Never leave boiled
instruments and other items in water that has stopped boiling; they can become
contaminated as the water cools.
• Addition of a 1-2% solution of sodium bicarbonate elevates the temperature
and helps to prevent corrosion of the instruments and utensils.
• The boiling point of water is affected by air pressure. At high altitudes, air
pressure is low, so is the boiling point of water, and disinfection time should be
prolonged. Generally, every 300 meters elevation is added, disinfection time
should be prolonged for 2 minutes.
• Pack the sharp instruments like scissors and knives with gauze so that they will
not be struck blunt. Pack small articles such as needles with gauze for easy take.
② Ultraviolet (UV) Light Radiation
UV light is electromagnetic wave with a wave length of 210-328nm. The wave
length with the best anti-bacterial effect is 250-270nm. UV light can kill such
microorganisms as bacteria, viruses, fungi and parts of spores, but in practice it is
affected by environmental factors like penetration ability, temperature and relative
humidity. Attention should be paid to:
• Penetration ability of UV light. The penetration ability of UV light is weak. It
can only kill the microorganisms it directly radiates. Dust, paper and glass can
affect the penetration of UV light.
• Temperature. Suitable temperature for UV light to kill microorganisms ranges
from 20 ºC to 40 ºC. At 40 ºC, UV light can best kill microorganisms because
its radiation energy is the greatest.
• Humidity. The suitable humidity is 40%-60%. The lower the relative humidity,
the better UV light kills the microorganisms. If relative humidity is great, the
particles in the air become larger, which lowers the penetration ability of UV
light.
Uses:
• Air disinfection. There should be a 30W UV light tube for every 10 square
meters of room with the effective distance of no more than 2 meters and the
radiation time of 30-60 min.
• Object surface disinfection. When objects are disinfected, a 30W UV tube can
be used at an effective distance of 25-60 cm, and the objects should be tuned
around frequently to make every side being radiated for 20-30min.
• Fluid disinfection. The fluid depth should be less than 2 cm. Determine the
fluid velocity according to UV radiation intensity.
Notes:
• Use alcohol cotton to gently clean the surfaces of the UV light tube to remove
46
dust and oily dirt so that the radiation effects will not be lowered. When turned
off, the light tube should be cooled off for 3-4 minutes before being turned on
again or moved away in order not to damage the light tube.
• Keep room clean and dry. There should not be too much dust in the air. Keep
temperature and relative humidity suitable to guarantee the best disinfection
effects. If temperature is too low or relative humidity is too high, prolong the
radiation time.
• There are 15W, 25W, 30W and 40W UV light tubes available. They can be
hung, put on a portable shelves or in a chamber. Record radiation time after the
UV light has been on for 5-7 minutes.
• UV light strongly irritates eyes and skin of human beings. The ozone produced
during radiation is also harmful to the body. Keep people off the room being
radiated or cover eyes with gauze and cover exposed extremities. In order to
prevent the side-effects of too much ozone, when people are around, the
radiation time should not be more than 2 hours.
• Regularly check the output of the UV light tube. If it is lower than 70µW/cm 2,
change the tube. Keep a record of the working time of the tube. When the
working time is over 1000 hours, change the tube.
③ Microwave Oven
Microwave is a kind of electromagnetic wave with high frequency (30-300
000MHz) and short wave (0.001-1m). The mechanism of microwave disinfecting
objects is that in high-frequency electric field of electromagnetic wave, the polar
molecules of the objects move with high speed and frequently change directions,
causing the temperature rise quickly. It is suitable for the disinfection of food,
tableware, medication and some heat-tolerant non-metal instruments.
Notes:
• Microwave is harmful to health, so avoid long term contact in small dose or
large dose.
• Microwave can not penetrate metal, so do not put objects in metal container.
• Water is a strong microwave absorbing medium, so object wrapped by wet
cloth or put a glass of water in the microwave oven can enhance disinfection
efficacy.
④ Chemical HLD
Before deciding to use a chemical disinfectant, consider whether a more
appropriate method is available. Chemical disinfection is used most commonly for
heat-labile equipment (e.g. endoscopes) where single use is not cost effective.
A limited number of disinfectants can be used for this purpose. e.g.:
• Glutaraldehyde 2%
• Hydrogen peroxide 6% - 7.5%
• Ortho-phthalaldehyde (OPA)
i. Glutaraldehyde
Uses:
High level disinfection is achieved after at least 20 minutes at 20°C. Refer to
product label for time and temperature required to achieve high level disinfection.
47
• Heat sensitive equipment/devices
• Lensed instruments that do not require sterilization
• Endoscopes
• Respiratory therapy equipment
• Anaesthesia equipment
Advantages:
• Noncorrosive to metal, plastic, rubber, lens cements
• Active in presence of organic material
Disadvantages:
•
• Need proper ventilation & closed containers
• During reuse, concentration may drop as dilution of the product occurs
ii. Hydrogen peroxide
Uses:
High level disinfection is achieved after at least 30 minutes.
•
-critical equipment used for home health care
• Disinfection of soft contact lenses
Advantages:
•
• Rapid action
• Safe for the environment
• Low cost
Disadvantages:
•
otect from light
• Contraindicated for use on copper, brass, carbon-tipped devices and aluminum
iii. Ortho-phthalaldehyde (OPA)
Uses:
High level disinfection is achieved after at least 10 minutes at 20°C. The object
must be thoroughly rinsed with sterile water after disinfection. If sterile water is not
available, freshly boiled water can be used. After rinsing, items must be kept dry and
stored properly.
•
• Heat sensitive equipment/devices
Advantages:
• Superior penetration
• Rapid activity
• Active in presence of organic materials
• Non-irritating vapour
• Does not require activation or dilution
Disadvantages:
•
rotein, including hands, requiring gloves and gown for use
• Expensive
II. Intermediate Level Disinfection (ILD)
①Alcohols
48
Uses:
Use 70%-75% solution to disinfect skin. When it is used to other objects,
disinfection is achieved after 10 minutes of contact.
•
• Noncritical equipment used for home health care
Advantages:
• Non-toxic
• Low cost
• Rapid action
• Non-staining
• No residue
• Effective on clean equipment/devices that can be immersed
Disadvantages:
• Evaporates quickly - not a good surface disinfectant
• Evaporation may diminish concentration
• Flammable - store in a cool well ventilated area;
• Coagulates protein; a poor cleaner
• Hardens and swells plastic tubing
• Harmful to silicone; causes brittleness
• May harden rubber or cause deterioration of glues
• Inactivated by organic material
②Chlorines
Uses:
It is suitable to disinfect dishware, environment, water, et al.
Advantages:
•
• Rapid action
Disadvantages:
•
• Inactivated by organic material;
• Irritant to skin and mucous membranes
• Should be used immediately once diluted
• Use in well-ventilated areas
• Must be stored in closed containers away from ultraviolet light & heat to
prevent deterioration
•
③Iodophors
Uses:
• Disinfect injection site or operation area by scrubbing them with iodophor
solution containing 0.5%-2% active iodine.
• Use iodophor solution containing 0.1% active iodine to disinfect thermometers
• Use iodophor solution containing 0.05% active iodine to scrub or rinse the
mucus of mouth, burn wound and injured wound.
Advantages:
49
•
• Non-toxic
Disadvantages:
•
• Inactivated by organic materials
• May stain fabrics and synthetic materials
III. Low Level Disinfection (LLD)
① Quaternary ammonium compounds (QUATs)
Uses:
•
Advantages:
• Non corrosive, non-toxic, low irritant
• Good cleaning ability, usually have detergent properties
• Rinsing not required
• May be used on food surfaces
Disadvantages:
•
struments
• Limited use as disinfectant because of narrow microbicidal spectrum
• Diluted solutions may support the growth of microorganisms
• May be neutralized by various materials (e.g. gauze)
Notes for chemical sterilization/disinfection:
• Clean, and dry all items to be sterilized /disinfected. Water from wet instruments
and from other items dilutes the chemical solution, thereby reducing its
effectiveness.
• Prepare the chemical solution following the manufacturer’s instructions.
Concentration of used disinfectant and contact time should be revised because
different companies provide different concentrations for a single disinfectant, so
manufacture’s instructions should be carefully read before use.
• If using a previously prepared solution, use an indicator strip to determine if the
solution is still effective. If preparing a new solution, put it in a sterile/clean
container with a lid and mark the container with the preparation date and
expiration date.
• Open all hinged instruments and other items. Disassemble those instruments with
multiple parts because the solution must contact all surfaces for sterilization
/disinfection to be achieved.
• Place all items in the solution so that they are completely submerged. Place bowls
and containers upright so that they are filled with the solution.
• Cover the container and follow the manufacturer’s instructions regarding the time
necessary for sterilization/disinfection. During this period, do not add or remove
any items from the container.
• Rinse thoroughly with sterilized/boiled water to remove the residue that is left on
items. This residue is toxic to skin and to tissues.
• Antiseptics should never be used for HLD. They are for use on the skin and
50
mucous membranes, not on inanimate objects. Sterilant/Disinfectants should
always be stored in a cool, dark place; they should never be stored in direct light
or excessive heat.
Daily Cleaning, Disinfection and Sterilization in Hospital
Hospital environment
Environmental air disinfection
According to air disinfection, hospital environment is classified by four
categories. ①I category includes laminar flow operation room, laminar flow ward and
sterile pharmaceutical preparation room, et al. it need laminar flow to purify air. ②II
category includes operation room, obstetrical ward，infant room, premature infant
room, protective isolation room, burn ward, ICU, et al. Use air disinfector made of
ozone ultraviolet light to disinfect the air. ③III category includes pediatric ward,
obstetric and gynecologic examination room, injection room, emergency room, ward,
et al. Besides methods in category II, we use ozone, ultraviolet light, and chemical
solution to disinfect air. ④IV category includes contagious ward. Use methods in
category II and III to disinfect air.
Environmental surface disinfection
① Floor: If no obvious contamination, clean the dirty area and part
microorganisms; if contaminated by pathogenic microorganisms, use chemical
disinfectants to mop or spay the floor. ②Wall: Do not need regular disinfection; if
contaminated, use chemical disinfectants to spay or rub the wall. ③Object surfaces:
Use wet cloth or cloth with disinfection solution to rub the surfaces such as bed,
bedside tables, chair, doorknob, tap, windows, door and urinal. If contaminated, use
chemical disinfectant to spay or rub them, or use ultraviolet light.
Preventive disinfection and disinfection of epidemic focus
Preventive disinfection
Disinfection of epidemic focus
• Concurrent disinfection
• Terminal disinfection
Textiles and laundry
The textiles and laundry used by patients are sterilized by ethylene oxide, then
washed and prepared for use. If there is no ethylene oxide sterilization room, use the
following methods: ① wash and then disinfect patients’ cloth and sheet use by high
temperature; ②use ultraviolet light to disinfect blankets, pillows, bed mattress;
③wash and disinfect contagious patients’ and other patients’ textiles and laundry
separately; ④wash and disinfect health care workers’ and patients’ textiles and
laundry separately. In addition, take measures to protect health care workers and
disinfect collecting cart, washing machine, washing room, et al.
Skin and mucous membrane
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Skin and mucous membrane provide protective barrier to microorganisms.
Remember when performing skin and mucous membrane disinfection: ①health care
workers perform hand hygiene to prevent cross-infection. ②choose appropriate
antiseptics according to patients’ skin and mucous membrane site, pathogenic
microorganisms. Use 2% iodine tincture to disinfect skin, after dry deiodinize it with
75% alcohol. Or use 0.5% iodophor.
Equipment, instruments/devices
Medical equipment and instruments/devices must be cleaned and maintained
according to the manufacturers’ instructions to prevent patient-to-patient transmission
of infectious agents. Cleaning to remove organic material must always precede high
level disinfection and sterilization of critical and semi-critical instruments and devices
because residual proteinacous material reduces the effectiveness of the disinfection
and sterilization processes. Noncritical equipment, such as commodes, intravenous
pumps, and ventilators, must be thoroughly cleaned and disinfected before use on
another patient. All such equipment and devices should be handled in a manner that
will prevent HCW and environmental contact with potentially infectious material.
Waste and sewage
Surveillance of cleaning, disinfection and sterilization efficacy
Environmental air, object surfaces and HCW’s hands
I, II category: can not detect Staphylococcus aureus, Escherichia coli and
Pseudomonas aeruginosa. III, IVcategory: can not detect Staphylococcus aureus,
Escherichia coli. Salmonella, Streptococcus hemolyticus, Staphylococcus aureus,
Escherichia coli can not be detected on health care workers’ hands and object surfaces
in premature infant room, neonate room, infant room, mother-kid shared ward and
pediatric ward (see Table 7-4).
Cfu standard of environmental air, object surfaces and HCW’s hands
Standard (cfu/cm2)
Category
Air
Object surfaces
HCW’s hands
I
≤10
≤5
≤5
II
≤200
≤5
≤5
III
≤500
≤10
≤10
IV
－
≤15
≤15
* cfu = colony forming units
Table 7-4
Equipment, instruments/devices
High risk items must be sterile. Any microorganisms can not be detected on them.
On intermediate risk items bacteria counts are less than 20cfu/g or 100 cm2 and
pathogenic microorganisms can not be detected. On low risk items bacteria counts are
less than 200cfu/g or 100 cm2 and pathogenic microorganisms can not be detected.
Disinfection solution
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Regularly detect the active ingredient in disinfection solution, bacteria counts are
less than 100cfu/ml and pathogenic microorganisms can not be detected. But this
disinfection solution can not be used to sterilization or immerse, store sterile items
and can not spay it in the air.
Stress under pressure and ultraviolet light
See above.
Dishware and eating utensils
Bacteria counts are less than 5cfu/cm2; HBsAg is negative; Escherichia coli and
other pathogenic microorganisms can not be detected.
Sanitary utensils
HBsAg is negative and pathogenic microorganisms can not be detected.
Drink water
Bacteria counts are less than 100/ml; Escherichia coli is less than 3/1000ml.
Textiles and laundry, medical waste
Pathogenic microorganisms can not be detected.
Waste
Pathogenic microorganisms can not be detected.
Hand Hygiene
Hand hygiene has been cited frequently as the single most important practice to
reduce the transmission of infectious agents in healthcare settings. The term “hand
hygiene” includes both handwashing with either plain or antiseptic-containing soap
and water, and use of alcohol-based products (gels, rinses, foams) that do not require
the use of water. In the absence of visible soiling of hands, approved alcohol-based
products for hand disinfection are preferred over antimicrobial or plain soap and water
because of their superior microbiocidal activity, reduced drying of the skin, and
convenience. Improved hand hygiene practices have been associated with a sustained
decrease in the incidence of MRSA and VRE infections primarily in the ICU. The
effectiveness of hand hygiene can be reduced by the type and length of fingernails.
Individuals wearing artifical nails have been shown to harbor more pathogenic
organisms, especially gram negative bacilli and yeasts, on the nails and in the
subungual area than those with native nails.
Most patient deaths and suffering attributable to healthcare-associated infections
can be prevented. Low-cost and simple practices already exist to prevent these
infections. Hand hygiene, a very simple action, remains the primary measure to
reduce health care-associated infection and the spread of antimicrobial resistance,
enhancing patient safety across all settings. Though the action is simple, the lack of
compliance among health-care providers is problematic throughout the world.
Convincing evidence demonstrates that improved hand hygiene can reduce the
frequency of healthcare-associated infections. Failure to comply with hand hygiene is
considered the leading cause of healthcare-associated infections, contributes to the
spread of multiresistant organisms, and is recognized as a significant contributor to
outbreaks of infection.
Improved hand hygiene practices are temporally related to the decreased
53
frequency of healthcare-associated infections and spread of multiresistant organisms.
In addition, reinforcement of hand hygiene practices helps to control epidemics in
health-care facilities. Hand hygiene reduces infections. As a result, it saves lives and
reduces morbidity and costs related to health care-associated infections.
Normal bacterial flora on hands
In 1938, Price established that bacteria recovered from the hands could be
divided into two categories, namely transient and resident. The resident flora consist
of microorganisms residing under the superficial cells of the stratum corneum, and
can also be found on the surface of the skin. Resident flora has two main protective
functions: microbial antagonism and the competition for nutrients in the ecosystem. In
general, resident flora is less likely to be associated with infections, but may cause
infections in sterile body cavities, in the eyes, or on non-intact skin.
Transient flora, which colonize the superficial layers of the skin, are more
amenable to removal by routine handwashing. Transient microorganisms do not
usually multiply on the skin, but they survive and sporadically multiply on skin
surface. They are often acquired by HCWs during direct contact with patients or
contaminated environmental surfaces adjacent to the patient, and are the organisms
most frequently associated with healthcare-associated infections. Some types of
contact are significantly associated with higher levels of bacterial contamination of
HCWs’ hands during routine neonatal care: respiratory secretions, nappy/diaper
change and direct skin contact. The transmissibility of transient flora depends on the
species, the number of microorganisms on the surface, and the skin moisture. The
hands of some HCWs may become persistently colonized by pathogenic flora such as
S. aureus, Gram-negative bacilli, or yeast.
Indications for handwashing and hand antisepsis
A. Wash hands with soap and water when visibly dirty or contaminated with
proteinaceous material, or visibly soiled with blood or other body fluids, or if
exposure to potential spore-forming organisms is strongly suspected or proven or
after using the restroom.
B. Preferably use an alcohol-based hand rub for routine hand antisepsis in all other
clinical situations described in items Ca to Cf listed below if hands are not visibly
soiled. Alternatively, wash hands with soap and water.
C. Perform hand hygiene:
a) before and after having direct contact with patients;
b) after removing gloves;
c) before handling an invasive device (regardless of whether or not gloves are used)
for patient care;
d) after contact with body fluids or excretions, mucous membranes, non-intact skin,
or wound dressings;
e) if moving from a contaminated body site to a clean body site during patient care;
f) after contact with inanimate objects (including medical equipment) in the
immediate vicinity of the patient;
54
D. Wash hands with either plain or antimicrobial soap and water or rub hands with an
alcohol-based formulation before handling medication and preparing food.
E. When alcohol-based hand rub is already used, do not use antimicrobial soap
concomitantly.
55
Hand hygiene technique
A. Apply a palmful of the product and cover all surfaces of the hands. Rub hands until
hands are dry.
B. When washing hands with soap and water, wet hands with water and apply the
amount of product necessary to cover all surfaces. Vigorously perform rotational
hand rubbing on both palms and interlace fingers to cover all surfaces. Rinse hands
with water and dry thoroughly with a single use towel. Use running and clean water
whenever possible. Use towel to turn off faucet.
C. Make sure hands are dry. Use a method that does not recontaminate hands. Make
sure towels are not used multiple times or by multiple people. Avoid using hot
water, as repeated exposure to hot water may increase the risk of dermatitis.
D. Liquid, bar, leaflet or powdered forms of plain soap are acceptable when washing
hands with a non-antimicrobial soap and water. When bar soap is used, small bars
of soap in racks that facilitate drainage should be used.
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Section 3 Aseptic Technique
Concepts
Aseptic technique refers to the practices which prevent microorganisms invading
human beings, and sterile objects and areas from being contaminated during medical
procedures and nursing interventions. It is very important for the nurses to grasp
infection knowledge and use aseptic procedure regulations are established according
to scientific principles. All hospital personnel should strictly observe them to guard
the safety of the clients.
Aseptic area refers to the sterile area which has not been contaminated.
Non-aseptic area is a non-sterilized area or an area having been sterilized but being
contaminated again.
Aseptic supply is an aseptic item physically or chemically sterilized.
Principles of Aseptic Technique
Environment:
• The environment should be clean, capacious, and disinfected routinely.
• The procedure table is clean, dry, and smooth and the layout is rational.
• 30 minutes before the procedures, stop cleaning the surroundings and minimize
moving to prevent dust from floating.
Staff:
• Wear mask and cap, trim fingernails and wash hands before aseptic procedures.
Wear sterile gown and sterile gloves if necessary.
Supply:
• Place aseptic supplies and non-aseptic supplies separately and have distinct
label.
• Keep aseptic supply in sterile package or container. A sterile object or field
becomes contaminated by prolonged exposure to the air. Microorganisms
traveling through the air can fall on sterile items or fields.
• Label sterile packages with name, expiration date accurately and store them
according to expiration date.
• Keep sterile packages in a fixed, clean and dry place. Regularly check if the
sterile package are out of expiration date or wet. Expiration date is 7 days from
May 1 to October 1 and 14 days from October 1 to the next year’s May 1. If the
expiration duration is over or the package is wet, re-sterilize the items.
• A set of aseptic supply is only for a client to use once.
During procedures:
• Keep the body away from the aseptic area during procedures.
• Face sterile area during procedures. A sterile object or field out of the range of
vision is contaminated. Nurses never turn their backs on a sterile tray or leave it
unattended.
• Use sterile transfer forceps to fetch sterile items. A sterile object remains sterile
only when touched by another sterile object. Do not touch sterile objects with
57
non-sterile items, hands or forearms.
• Keep hands and arms above the waist level. Any object held below a person’s
waist level is considered contaminated because it can not be viewed at all times.
Do not reach over aseptic areas.
• Keep non-aseptic supplies away from aseptic supplies. Once taken out of the
container, aseptic supplies can not be put back even having not been used.
• No one should talk, laugh, cough or sneeze over a sterile filed or when
gathering and using sterile equipment.
• When in doubt about the sterility of a package, or consider it contaminated,
then re-sterilize the items. Use sterile items when performing aseptic
procedures. Non-sterile items or potentially contaminated items are inhibited.
• The edges of a sterile field or container are contaminated. The edges of sterile
container become exposed to air after they are open and are thus contaminated.
After a sterile needle is removed from its protective cap or after forceps are
removed from a container, the objects must not touch the container’s edge.
Aseptic Techniques
• Apply Sterile Transfer Forceps
• Apply Sterile Container
• Use Sterile Package
• Prepare Sterile Treatment Tray
• Pour Sterile Solution
• Don and Remove Sterile Gloves
Section 4 Isolation
Concepts
Isolation is the practices placing infectious clients and highly susceptible people in a
certain area to separate them from the others from the time being. The isolation for the
infected clients is called source isolation. The isolation for the susceptible people is
called protective isolation.
Clean area refers to the area not contaminated by pathogens as treatment room,
changeroom, and the areas other than wards, like canteen and pharmacy.
Half-contaminated area refers to the area that is potentially contaminated by
pathogens, like office, laboratory and disinfection room.
Contaminated area refers to the area contaminated by pathogens which is in contact
with clients directly and indirectly, such as ward, clients’ restroom and bathroom.
Isolation principals
Universal isolation
• Hang sign of isolation on the bed and the door. Put shoes scratch (moistened
with disinfectant solution to disinfect the bottoms of the shoes) and disinfectant
solution to immerse hands at the door.
• Wear cap, mask and isolation gown when entering the isolation room and
58
working in restricted area. Follow the isolation regulations when performing
whatever procedures. Disinfect hands after touching clients or contaminated
objects.
• Gather all the needed objects for nursing procedures before wearing isolation
gown. Be sure to carry out the nursing interventions according to the plan to
avoid donning and removing the gown and washing hands repeatedly.
• Strictly follow the accompanying and visiting regulations. Explain the
regulations to the clients, their accompanies and visitors in advance so that they
can follow the demand and regulation of isolation.
• Strictly disinfect the items used by a client before giving them to other clients.
Disinfect the excretion，secretion, vomits of the clients before disposing of it.
Make clean signs on the items and waste bags to be sent out and handled. Wrap
the items (watches) which are unsuitable for disinfection with paper, cloth or
plastic bag to avoid contamination.
• Spray disinfection solution or use ultraviolet light to disinfect the air and use
disinfection solution to scrub the client’s bed and chair once a day.
• Satisfy the psychological needs of the clients. Try best to relieve such
psychological reaction of the clients as horror, loneliness and pessimism caused
by isolation.
• Withdraw isolation upon ordered. Discontinue isolation after three cultures
proved negative.
Terminal disinfection
It is used to disinfect the transferred, discharged or dead clients and their ward,
objects and medical apparatus terminally.
Terminal disinfection of the client
Bathe the clients and let them put on clean clothes when they are transferred to
other wards or discharged, taking their personal items with them after disinfection.
For the dead client, clean the body with disinfectant and plug the mouth, nose, ears,
anus with sterile cotton, change wound dressing, envelop the body with disposable
linen.
Terminal disinfection of the ward
Close the doors and windows, open bedside table, spread the quilt and place the
mattress vertically on the bed, fumigate the items mentioned above with disinfectant
or disinfect by ultraviolet light, then open the door and windows, scratch the furniture
and floor with disinfectant, put the linen into the waste bag and clean them before
disinfection. Mattress, quilt and pillows can also be disinfected by being exposed to
ultraviolet light.
Types of Isolation and Practices
There are seven types of isolation depending on their transmission route, which
demand corresponding isolation practices.
Strict isolation
Contagious disease with strong infectivity and high mortality needs strict
isolation to cut its transmission route. Strict isolation is applicable for fulminating
59
contagious diseases which are directly and indirectly transmitted by droplets,
secretion or elimination, such as cholera, plague, SARS, avian influenza, et al. The
measures include:
• Place client in a single room. Close the door and windows facing the corridor.
The objects in the room should be simple and tolerate disinfection. Hang an
evident sign out of the room.
• Wear mask, cap, isolation gown, shoes and gloves (inject vaccine if necessary)
when in contact with the client. Take strict disinfection measures. Perform hand
hygiene after having direct contact with patients or contaminated objects and
before caring for another patient or leaving the room.
• Discharge vomits, excretions and secretions of the clients after strict
disinfection.
• Spray disinfection solution or use ultraviolet light to disinfect the air and the
floor of the room once a day.
• Limit the movement of client outside the room. In principal, visiting are not
allowed.
Contact isolation
It is suitable for diseases directly and indirectly infected through skin or wound
contact, such as tetanus, gas gangrene. The isolation measures include:
• Place client in a single room. Do not let the client come in contact with the
other clients.
• Wear isolation gown and gloves when touching the client or performing
procedures. Do not care for the client or do dressing if the staffs have cuts on
hands or arms. Perform hand hygiene after having direct contact with patients
or contaminated objects and before caring for another patient or leaving the
room.
• Sterilize first, then clean, disinfect and re-sterilize all the objects touched by the
client such as bed linen, clothes, and dressing apparatus. Burn the dressings
contaminated the wound drainage of the clients.
• In principal, visiting are not allowed.
Respiratory isolation
It is mainly used to prevent infectious disease transmitted by droplets nuclei in
short distance, such as influenza, epidemic encephalitis B and measles. The isolation
measures include:
• Place the cohort clients in a room. Keep isolation room far away from the other
rooms if possible. Close the door and windows facing the corridor to prevent
the pathogens from spreading outward. Ensure a respiratory isolation notice is
displayed on the door. Use ultraviolet light or spray disinfection solution to
disinfect the air once a day.
• Wear cap, mask and keep the mask dry when caring for the clients. Wear
gloves, isolation gown if necessary. Perform hand hygiene after having direct
contact with patients or contaminated objects and before caring for another
patient or leaving the room.
• Prepare sputum cups for the clients. Discard the secretion after strict
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disinfection.
• Visitors must have the staff’s permission before entering the room and take
some measures to protect themselves.
Enteric isolation
It is used for diseases which are caused directly and indirectly by contaminated
food or water by the client’s excretion, such as typhoid, bacillary dysentery, hepatitis
A. The isolation measures include:
• Place clients with different kind of diseases in different room and if in the same
room, label evident signs on the side of the bed. Clients are forbidden to
exchange books, newspapers or other items. Keep the room free from flies and
cockroach.
• Change isolation gown and gloves when caring for clients with different
diseases. Perform hand hygiene after having direct contact with patients or
contaminated objects and before caring for another patient or leaving the room.
• Clients use their own strictly-disinfected tableware and bedpans or urinals.
Disinfect the leftover or discharge before disposing of them.
• Put objects contaminated by excretion into a labeled waste bag, then send for
disposal or disinfection.
• Visitors must have the staff’s permission before entering the room and take
some measures to protect themselves.
Blood-body fluid isolation
It is used to prevent the infectious diseases caused by the direct or indirect
contact with contagious blood or body fluid, such as hepatitis B, AIDS, and syphilis.
The isolation measures include:
• Place the clients infected with/by the same pathogens at the same room. Isolate
the client who is not able to accomplish self-care or with uncontrollable
bleeding which contaminating the environment.
• Wear mask and goggled in case the blood and body fluid splash. Wear isolation
gown if the clothes is potentially contaminated by blood or body fluid. Wear
gloves when it is possible to touch blood or body fluid. If hands are
contaminated or potentially contaminated by blood or body fluid, use
disinfectant to wash hands immediately. Wash hands between client contacts.
• Immediately disinfect the objects in the room contaminated by blood or body
fluid. Put objects contaminated by blood or body fluid into a labeled waste bag,
then send for disposal or disinfection.
• Visitors must have the staff’s permission before entering the room and take
some measures to protect themselves.
Insect isolation
It is suitable for diseases transmitted by insects like encephalitis B, malaria, et al.
There should be mosquito net or other equipments in the room to prevent mosquitoes.
When typhus client is hospitalized, he should be disinfected to kill fleas before
entering and living with cohort clients.
Protective isolation
It is also called reverse isolation, suitable for the clients whose resistance is very
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low or who is highly susceptible, such as extensive burn patient, premature neonate,
leukemia and transplantation client. The isolation measures include:
• Place client in a single room or isolation unit. Ensure a protective isolation
notice is displayed on the door.
• Keep the door of the room closed. Ideally the air in the room should be under
slightly positive pressure, i.e. the airflow should be from the room to the
corridor and not from the corridor into the room. Strictly disinfect the floor and
furniture in case of the infections caused by pathogens that the health care
workers carry.
• Wear mask, cap gloves, overshoes, and gown (the outer side of the gown is
clean and the inner side is contaminated) before in contact with the client.
Objects which are not disinfected can not bring into the isolation area. Perform
hand hygiene before and after having direct contact with patients or before
caring for another patient.
• Put drainage, excretion and objects contaminated by blood or body fluid into a
labeled waste bag, then send for disposal or disinfection.
• Keep people suffering from respiratory diseases or carrying pathogens in the
throat away from the client. Staff with infections should avoid nursing patients
in protective isolation. In principle, to reduce the risk of cross infection, visitors
are not allowed. If allowed, visitors must wear protective clothing prior to
entering the room.
Personal protective equipment (PPE) for healthcare personnel
PPE refers to a variety of barriers and respirators used alone or in combination to
protect mucous membranes, airways, skin, and clothing from contact with infectious
agents. The selection of PPE is based on the nature of the patient interaction and/or
the likely mode(s) of transmission. Designated containers for used disposable or
reusable PPE should be placed in a location that is convenient to the site of removal to
facilitate disposal and containment of contaminated materials. Hand hygiene is always
the final step after removing and disposing of PPE. The following sections highlight
the primary uses and methods for selecting this equipment.
Gloves
Gloves are used to prevent contamination of healthcare personnel hands when 1)
anticipating direct contact with blood or body fluids, mucous membranes, nonintact
skin and other potentially infectious material; 2) having direct contact with patients
who are colonized or infected with pathogens transmitted by the contact route e.g.,
VRE, MRSA, RSV; or 3) handling or touching visibly or potentially contaminated
patient care equipment and environmental surfaces. Gloves can protect both patients
and healthcare personnel from exposure to infectious material that may be carried on
hands. The extent to which gloves will protect healthcare personnel from transmission
of bloodborne pathogens (e.g., HIV, HBV, HCV) following a needlestick or other
puncture that penetrates the glove barrier has not been determined. Although gloves
may reduce the volume of blood on the external surface of a sharp by 46-86%, the
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residual blood in the lumen of a hollow bore needle would not be affected; therefore,
the effect on transmission risk is unknown. Nonsterile disposable medical gloves
made of a variety of materials (e.g., latex, vinyl, nitrile) are available for routine
patient care. The selection of glove type for non-surgical use is based on a number of
factors, including the task that is to be performed, anticipated contact with chemicals
and chemotherapeutic agents, latex sensitivity, sizing, and facility policies for creating
a latex-free environment. For contact with blood and body fluids during non-surgical
patient care, a single pair of gloves generally provides adequate barrier protection. It
may be necessary to stock gloves in several sizes. Heavier, reusable utility gloves are
indicated for non-patient care activities, such as handling or cleaning contaminated
equipment or surfaces. During patient care, transmission of infectious organisms can
be reduced by adhering to the principles of working from “clean” to “dirty”, and
confining or limiting contamination to surfaces that are directly needed for patient
care. It may be necessary to change gloves during the care of a single patient to
prevent cross-contamination of body sites. It also may be necessary to change gloves
if the patient interaction also involves touching portable computer keyboards or other
mobile equipment that is transported from room to room. Discarding gloves between
patients is necessary to prevent transmission of infectious material. Gloves must not
be washed for subsequent reuse because microorganisms cannot be removed reliably
from glove surfaces and continued glove integrity cannot be ensured. Furthermore,
glove reuse has been associated with transmission of MRSA and gram-negative
bacilli. When gloves are worn in combination with other PPE, they are put on last.
Gloves that fit snugly around the wrist are preferred for use with an isolation gown
because they will cover the gown cuff and provide a more reliable continuous barrier
for the arms, wrists, and hands. Gloves that are removed properly will prevent hand
contamination. Hand hygiene following glove removal further ensures that the hands
will not carry potentially infectious material that might have penetrated through
unrecognized tears or that could contaminate the hands during glove removal.
Isolation gowns
Isolation gowns are used as specified by Standard and Transmission-Based
Precautions, to protect the HCW’s arms and exposed body areas and prevent
contamination of clothing with blood, body fluids, and other potentially infectious
material. The need for and type of isolation gown selected is based on the nature of
the patient interaction, including the anticipated degree of contact with infectious
material and potential for blood and body fluid penetration of the barrier. Clinical and
laboratory coats or jackets worn over personal clothing for comfort and/or purposes of
identity are not considered PPE. When applying Standard Precautions, an isolation
gown is worn only if contact with blood or body fluid is anticipated. However, when
Contact Precautions are used (i.e., to prevent transmission of an infectious agent that
is not interrupted by Standard Precautions alone and that is associated with
environmental contamination), donning of both gown and gloves upon room entry is
indicated to address unintentional contact with contaminated environmental surfaces.
The routine donning of isolation gowns upon entry into an intensive care unit or other
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high-risk area does not prevent or influence potential colonization or infection of
patients in those areas. Isolation gowns are always worn in combination with gloves,
and with other PPE when indicated. Gowns are usually the first piece of PPE to be
donned. Full coverage of the arms and body front, from neck to the mid-thigh or
below will ensure that clothing and exposed upper body areas are protected. Several
gown sizes should be available in a healthcare facility to ensure appropriate coverage
for staff members. Isolation gowns should be removed before leaving the patient care
area to prevent possible contamination of the environment outside the patient’s room.
Isolation gowns should be removed in a manner that prevents contamination of
clothing or skin. The outer, “contaminated”, side of the gown is turned inward and
rolled into a bundle, and then discarded into a designated container for waste or linen
to contain contamination.
Face protection: masks, goggles, face shields
Masks
Masks are used for three primary purposes in healthcare settings: 1) placed on
healthcare personnel to protect them from contact with infectious material from
patients e.g., respiratory secretions and sprays of blood or body fluids, consistent with
Standard Precautions and Droplet Precautions; 2) placed on healthcare personnel
when engaged in procedures requiring sterile technique to protect patients from
exposure to infectious agents carried in a healthcare worker’s mouth or nose, and 3)
placed on coughing patients to limit potential dissemination of infectious respiratory
secretions from the patient to others (i.e., Respiratory Hygiene/Cough Etiquette).
Masks may be used in combination with goggles to protect the mouth, nose and eyes,
or a face shield may be used instead of a mask and goggles, to provide more complete
protection for the face, as discussed below. Masks should not be confused with
particulate respirators that are used to prevent inhalation of small particles that may
contain infectious agents transmitted via the airborne route as described below.
The mucous membranes of the mouth, nose, and eyes are susceptible portals of
entry for infectious agents, as can be other skin surfaces if skin integrity is
compromised (e.g., by acne, dermatitis). Therefore, use of PPE to protect these body
sites is an important component of Standard Precautions. The protective effect of
masks for exposed healthcare personnel has been demonstrated. Procedures that
generate splashes or sprays of blood, body fluids, secretions, or excretions (e.g.,
endotracheal suctioning, bronchoscopy, invasive vascular procedures) require either a
face shield (disposable or reusable) or mask and goggles. Appropriate PPE should be
selected based on the anticipated level of exposure. Masks come in various shapes
(e.g., molded and non-molded), sizes, filtration efficiency, and method of attachment
(e.g., ties, elastic, ear loops). Healthcare facilities may find that different types of
masks are needed to meet individual healthcare personnel needs.
Goggles, face shields
The eye protection chosen for specific work situations (e.g., goggles or face
shield) depends upon the circumstances of exposure, other PPE used, and personal
vision needs. Personal eyeglasses and contact lenses are NOT considered adequate
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eye protection Eye protection must be comfortable, allow for sufficient peripheral
vision, and must be adjustable to ensure a secure fit. It may be necessary to provide
several different types, styles, and sizes of protective equipment. Indirectly-vented
goggles with a manufacturer’s anti-fog coating may provide the most reliable
practical eye protection from splashes, sprays, and respiratory droplets from multiple
angles. Newer styles of goggles may provide better indirect airflow properties to
reduce fogging, as well as better peripheral vision and more size options for fitting
goggles to different workers. Many styles of goggles fit adequately over prescription
glasses with minimal gaps. While effective as eye protection, goggles do not provide
splash or spray protection to other parts of the face.
Disposable or non-disposable face shields may be used as an alternative to
goggles. As compared with goggles, a face shield can provide protection to other
facial areas in addition to the eyes. Face shields extending from chin to crown provide
better face and eye protection from splashes and sprays; face shields that wrap around
the sides may reduce splashes around the edge of the shield. Removal of a face shield,
goggles and mask can be performed safely after gloves have been removed, and hand
hygiene performed. The ties, ear pieces and/or headband used to secure the equipment
to the head are considered “clean” and therefore safe to touch with bare hands. The
front of a mask, goggles and face shield are considered contaminated.
Respiratory protection
Respiratory protection currently requires the use of a respirator with N95 or
higher filtration to prevent inhalation of infectious particles. A user-seal check
(formerly called a “fit check”) should be performed by the wearer of a respirator each
time a respirator is donned to minimize air leakage around the facepiece. CDC
currently recommends N95 or higher level respirators for personnel exposed to
patients with suspected or confirmed tuberculosis. Currently this is also true for other
diseases that could be transmitted through the airborne route, including SARS and
smallpox, until inhalational transmission is better defined or healthcare-specific
protective equipment more suitable for preventing infection are developed.
Respirators are also currently recommended to be worn during the performance of
aerosol-generating procedures (e.g., intubation, bronchoscopy, suctioning) on patients
with SARS Co-V infection, avian influenza and pandemic influenza. In some
healthcare settings, particulate respirators used to provide care for patients with M.
tuberculosis are reused by the same HCW. This is an acceptable practice providing
the respirator is not damaged or soiled, the fit is not compromised by change in shape,
and the respirator has not been contaminated with blood or body fluids. There are no
data on which to base a recommendation for the length of time a respirator may be
reused.
Precautions to Prevent Transmission of Infectious Agents
There are two tiers of CDC precautions to prevent transmission of infectious
agents, Standard Precautions and Transmission-Based Precautions. Standard
Precautions are intended to be applied to the care of all patients in all healthcare
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settings, regardless of the suspected or confirmed presence of an infectious agent.
Implementation of Standard Precautions constitutes the primary strategy for the
prevention of healthcare-associated transmission of infectious agents among patients
and healthcare personnel. Transmission-Based Precautions are for patients who are
known or suspected to be infected or colonized with infectious agents, including
certain epidemiologically important pathogens, which require additional control
measures to effectively prevent transmission. Since the infecting agent often is not
known at the time of admission to a healthcare facility, Transmission-Based
Precautions are used empirically, according to the clinical syndrome and the likely
etiologic agents at the time, and then modified when the pathogen is identified or a
transmissible infectious etiology is ruled out.
Standard Precautions
Standard Precautions are based on the principle that all blood, body fluids,
secretions, excretions except sweat, nonintact skin, and mucous membranes may
contain transmissible infectious agents. Standard Precautions include a group of
infection prevention practices that apply to all patients, regardless of suspected or
confirmed infection status, in any setting in which healthcare is delivered. These
include: hand hygiene; use of gloves, gown, mask, eye protection, or face shield,
depending on the anticipated exposure; and safe injection practices. Also, equipment
or items in the patient environment likely to have been contaminated with infectious
body fluids must be handled in a manner to prevent transmission of infectious agents
(e.g. wear gloves for direct contact, contain heavily soiled equipment, properly clean
and disinfect or sterilize reusable equipment before use on another patient). The
application of Standard Precautions during patient care is determined by the nature of
the HCW-patient interaction and the extent of anticipated blood, body fluid, or
pathogen exposure. For some interactions (e.g., performing venipuncture), only
gloves may be needed; during other interactions (e.g., intubation), use of gloves,
gown, and face shield or mask and goggles is necessary. Standard Precautions are also
intended to protect patients by ensuring that healthcare personnel do not carry
infectious agents to patients on their hands or via equipment used during patient care.
Respiratory Hygiene/Cough Etiquette
The transmission of SARS Co-V in emergency departments by patients and their
family members during the widespread SARS outbreaks in 2003 highlighted the need
for vigilance and prompt implementation of infection control measures at the first
point of encounter within a healthcare setting (e.g., reception and triage areas in
emergency departments, outpatient clinics, and physician offices). The strategy
proposed has been termed Respiratory Hygiene/Cough Etiquette and is intended to be
incorporated into infection control practices as a new component of Standard
Precautions. The strategy is targeted at patients and accompanying family members
and friends with undiagnosed transmissible respiratory infections, and applies to any
person with signs of illness including cough, congestion, rhinorrhea, or increased
production of respiratory secretions when entering a healthcare facility. The elements
of Respiratory Hygiene/Cough Etiquette include 1) education of healthcare facility
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staff, patients, and visitors; 2) posted signs, in language(s) appropriate to the
population served, with instructions to patients and accompanying family members or
friends; 3) source control measures (e.g., covering the mouth/nose with a tissue when
coughing and prompt disposal of used tissues, using surgical masks on the coughing
person when tolerated and appropriate); 4) hand hygiene after contact with respiratory
secretions; and 5) spatial separation, ideally >3 feet, of persons with respiratory
infections in common waiting areas when possible. Covering sneezes and coughs and
placing masks on coughing patients are proven means of source containment that
prevent infected persons from dispersing respiratory secretions into the air. Masking
may be difficult in some settings, (e.g., pediatrics, in which case, the emphasis by
necessity may be on cough etiquette. Physical proximity of <3 feet has been
associated with an increased risk for transmission of infections via the droplet route
(e.g., N. meningitidis and group A streptococcus and therefore supports the practice of
distancing infected persons from others who are not infected. The effectiveness of
good hygiene practices, especially hand hygiene, in preventing transmission of viruses
and reducing the incidence of respiratory infections both within and outside
healthcare settings is summarized in several reviews.
These measures should be effective in decreasing the risk of transmission of
pathogens contained in large respiratory droplets (e.g., influenza virus, adenovirus, B.
pertussis and Mycoplasma pneumoniae. Although fever will be present in many
respiratory infections, patients with pertussis and mild upper respiratory tract
infections are often afebrile. Therefore, the absence of fever does not always exclude
a respiratory infection. Patients who have asthma, allergic rhinitis, or chronic
obstructive lung disease also may be coughing and sneezing. While these patients
often are not infectious, cough etiquette measures are prudent. Healthcare personnel
are advised to observe Droplet Precautions (i.e., wear a mask) and hand hygiene when
examining and caring for patients with signs and symptoms of a respiratory infection.
Healthcare personnel who have a respiratory infection are advised to avoid direct
patient contact, especially with high risk patients. If this is not possible, then a mask
should be worn while providing patient care.
Transmission-Based Precautions
There are three categories of Transmission-Based Precautions: Contact
Precautions, Droplet Precautions, and Airborne Precautions. Transmission-Based
Precautions are used when the route(s) of transmission is (are) not completely
interrupted using Standard Precautions alone. For some diseases that have multiple
routes of transmission (e.g., SARS), more than one Transmission-Based Precautions
category may be used. When used either singly or in combination, they are always
used in addition to Standard Precautions. When Transmission-Based Precautions are
indicated, efforts must be made to counteract possible adverse effects on patients (i.e.,
anxiety, depression and other mood disturbances, perceptions of stigma, reduced
contact with clinical staff, and increases in preventable adverse events in order to
improve acceptance by the patients and adherence by HCWs.
Contact Precautions
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Contact Precautions are intended to prevent transmission of infectious agents,
including epidemiologically important microorganisms, which are spread by direct or
indirect contact with the patient or the patient’s environment. Contact Precautions also
apply where the presence of excessive wound drainage, fecal incontinence, or other
discharges from the body suggest an increased potential for extensive environmental
contamination and risk of transmission. A single patient room is preferred for patients
who require Contact Precautions. When a single-patient room is not available,
consultation with infection control personnel is recommended to assess the various
risks associated with other patient placement options (e.g., cohorting, keeping the
patient with an existing roommate). In multi-patient rooms, >3 feet spatial separation
between beds is advised to reduce the opportunities for inadvertent sharing of items
between the infected/colonized patient and other patients. Healthcare personnel caring
for patients on Contact Precautions wear a gown and gloves for all interactions that
may involve contact with the patient or potentially contaminated areas in the patient’s
environment. Donning PPE upon room entry and discarding before exiting the patient
room is done to contain pathogens, especially those that have been implicated in
transmission through environmental contamination (e.g., VRE, C. difficile,
noroviruses and other intestinal tract pathogens; RSV).
Droplet Precautions
Droplet Precautions are intended to prevent transmission of pathogens spread
through close respiratory or mucous membrane contact with respiratory secretions.
Because these pathogens do not remain infectious over long distances in a healthcare
facility, special air handling and ventilation are not required to prevent droplet
transmission. Infectious agents for which Droplet Precautions are indicated include B.
pertussis, influenza virus, adenovirus, rhinovirus, N. meningitides, and group A
streptococcus (for the first 24 hours of antimicrobial therapy). A single patient room is
preferred for patients who require Droplet Precautions. When a single-patient room is
not available, consultation with infection control personnel is recommended to assess
the various risks associated with other patient placement options (e.g., cohorting,
keeping the patient with an existing roommate). Spatial separation of > 3 feet and
drawing the curtain between patient beds is especially important for patients in
multi-bed rooms with infections transmitted by the droplet route. Healthcare
personnel wear a mask (a respirator is not necessary) for close contact with infectious
patient; the mask is generally donned upon room entry. Patients on Droplet
Precautions who must be transported outside of the room should wear a mask if
tolerated and follow Respiratory Hygiene/Cough Etiquette.
Airborne Precautions
Airborne Precautions prevent transmission of infectious agents that remain
infectious over long distances when suspended in the air (e.g., rubeola virus [measles],
varicella virus [chickenpox], M. tuberculosis, and possibly SARS-CoV). The
preferred placement for patients who require Airborne Precautions is in an airborne
infection isolation room (AIIR). An AIIR is a single-patient room that is equipped
with special air handling and ventilation capacity. In settings where Airborne
Precautions cannot be implemented due to limited engineering resources (e.g.,
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physician offices), masking the patient, placing the patient in a private room (e.g.,
office examination room) with the door closed, and providing N95 or higher level
respirators or masks if respirators are not available for healthcare personnel will
reduce the likelihood of airborne transmission until the patient is either transferred to
a facility with an AIIR or returned to the home environment, as deemed medically
appropriate. Healthcare personnel caring for patients on Airborne Precautions wear a
mask or respirator, depending on the disease-specific recommendations, that is
donned prior to room entry. Whenever possible, non-immune HCWs should not care
for patients with vaccine-preventable airborne diseases (e.g., measles, chickenpox,
and smallpox).
Syndromic
and
empiric
applications
of
Transmission-Based
Precautions
Diagnosis of many infections requires laboratory confirmation. Since laboratory
tests, especially those that depend on culture techniques, often require two or more
days for completion, Transmission-Based Precautions must be implemented while test
results are pending based on the clinical presentation and likely pathogens. Use of
appropriate Transmission-Based Precautions at the time a patient develops symptoms
or signs of transmissible infection, or arrives at a healthcare facility for care, reduces
transmission opportunities. While it is not possible to identify prospectively all
patients needing Transmission-Based Precautions, certain clinical syndromes and
conditions carry a sufficiently high risk to warrant their use empirically while
confirmatory tests are pending.
Discontinuation of Transmission-Based Precautions
Transmission-Based Precautions remain in effect for limited periods of time (i.e.,
while the risk for transmission of the infectious agent persists or for the duration of
the illness. For most infectious diseases, this duration reflects known patterns of
persistence and shedding of infectious agents associated with the natural history of the
infectious process and its treatment. For some diseases (e.g., pharyngeal or cutaneous
diphtheria, RSV), Transmission-Based Precautions remain in effect until culture or
antigen-detection test results document eradication of the pathogen and, for RSV,
symptomatic disease is resolved. In immunocompromised patients, viral shedding can
persist for prolonged periods of time (many weeks to months) and transmission to
others may occur during that time; therefore, the duration of contact and/or droplet
precautions may be prolonged for many weeks.
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