Download Hospital-Acquired Infection (Nosocomial Infection)

Hospital-Acquired Infection
(Nosocomial Infection)
Lecture 4
Hazem Al-Khafaji
Department of internal medicine
college of medicine
Al-Qadissyia university
Definition
Nosocomial infections are infections
acquired in hospitals and other healthcare
facilities. The infection to be classified as
nosocomial infection should be:
1- The patient must have been admitted for
reasons other than the infection.
2- The patient must also have shown no
signs of active or incubating infection.
The nosocomial infections
occur:
up to 48 hours after hospital admission
up to 3 days after discharge from the hospital
up to 30 days after an operation in a healthcare
facility when a patient was admitted for reasons
other than the infection
Epidemiology
In the United States, it has been estimated
that 9.2 out of every 100 patients acquire a
nosocomial infection.
 In UK about 6-10%.


100,000 infections per year in UK
5,000 deaths with nosocomial infections
playing a role in 15,000 others.
Frequency of infection(WHO Report)
Nosocomial infections occur worldwide and affect
both developed and resource-poor countries.
Infections acquired in health care settings are
among the major causes of death and increased
morbidity among hospitalized patients. They are a
significant burden both for the patient and for public
health.An average of 8.7% of hospital patients had
nosocomial infections. At any time, over 1.4 million
people worldwide suffer from infectious
complications acquired in hospital. The highest
frequencies of nosocomial infections were reported
from hospitals in the Eastern Mediterranean and
South-East Asia Regions (11.8 and 10.0%
What are the factors influence the
development of infection in hospital?
Consider
4
important
factors…
Treatment
The
environment
The host
The
microbes
The Cycle of Contagion
Pathogen
Transmission
Susceptible
person
Infection or
colonisation
Factors influencing the development of
nosocomial infections:
The microbial agent:
Factors leading to infection depends partly on
the:
1- characteristics of the microorganisms.
2- including resistance to antimicrobial
agents.
3- intrinsic virulence.
4- amount of infective material (inoculum) .
5-nosocomial infections are often caused by
opportunistic pathogens .
6- antibiotic resistance is a problem .
Environmental factors :
1- Health care settings are an environment
where both infected persons and persons at
increased risk of infection contact each other.
2- Patients with infections or carriers of
pathogenic microorganisms admitted to
hospital are potential sources of infection for
patients and staff.
3- Patients who become infected in the
hospital are a further source of infection.
4- Crowded conditions within the hospital.
5-Frequent transfers of patients from one unit
to another, and concentration of patients
highly susceptible to infection in one area.
Host(Patient) susceptibility:
Important patient factors influencing
acquisition of infection include
1- Age(the extremes of life — infancy and old
age — are associated with a decreased
resistance to infection).
2-Immune status.
3- Underlying disease.
4- Diagnostic and therapeutic interventions.
5-Patients with chronic disease such as
malignant tumors, leukemia, diabetes
mellitus, renal failure, or (AIDS) have an
increased susceptibility to infections with
Treatment:
The widespread use of antimicrobials for therapy or
prophylaxis (including topical) is the major cause of
development of resistance. Antimicrobial agents
are, in some cases, becoming less effective because
of resistance. As an antimicrobial agent becomes
widely used, bacteria resistant to this drug
eventually emerge and may spread in the health care
setting. Many strains of pneumococci,
staphylococci(Methicillin Resistant Staphylococcus
aureus (MRSA)
, enterococci, and tuberculosis are currently
resistant to most or all antimicrobials which were
once effective. Multiresistant Klebsiella and
Pseudomonas are prevalent in many hospitals.
Commonest nosocomial infections( Type
of nosocomial infection)
1- Urinary tract infection( Positive urine culture (1 or 2 species) with at least
100.000 bacteria/ml), with or without clinical symptoms.
2- Surgical site infection Any purulent discharge, abscess, or spreading cellulitis
at the surgical site during the month after the operation.
3- Respiratory infection:symptoms with at least two of the following signs
appearing during hospitalization: — cough — purulent sputum — new infiltrate on
chest radiograph consistent with infection.
4-Vascular catheter Inflammation, lymphangitis or infection purulent discharge at
the insertion site of the catheter .
5-Septicaemia Fever or rigors and at least one positive blood culture
6-Other nosocomial infections:
There are many other potential sites of infection. For
example: ● Skin and soft tissue infections: open
sores (ulcers, burns and bedsores) encourage
bacterial colonization and may lead to systemic
infection.
● Gastroenteritis is the most common nosocomial
infection in children, where rotavirus is a chief
pathogen: Clostridium difficile is the major cause of
nosocomial gastroenteritis in adults in developed
countries.
● Sinusitis and other enteric infections, infections of
the eye and conjunctiva.
● Endometritis and other infections of the
reproductive organs following childbirth.
Pathogens(Microorganisms ) cause nosocomial infections:
. The infecting organisms vary among different patient populations, different
health care settings, different facilities, and different countries.
1- Bacteria: These are the most common nosocomial pathogens.
A-Commensal bacteria may cause infection if the natural host is compromised.
For example, cutaneous coagulasenegative staphylococci cause intravascular
line infection and intestinal Escherichia coli are the most common cause of
urinary infection.
B-Pathogenic bacteria have greater virulence, and cause infections (sporadic or
epidemic) regardless of host status. For example: — Anaerobic Gram-positive
rods (e.g. Clostridium) cause gangrene. — Gram-positive bacteria:
Staphylococcus aureus (cutaneous bacteria that colonize the skin and nose of
both hospital staff and patients) cause a wide variety of lung, bone, heart and
bloodstream infections.
—
Gram-negative bacteria:
Enterobacteriacae (e.g. Escherichia coli, Proteus, Klebsiella, Enterobacter, may
colonize sites when the host defences are compromised (catheter insertion,
bladder catheter, cannula insertion) and cause serious infections (surgical site,
lung, bacteraemia, peritoneum infection).
They may also be highly resistant.
Gram-negative organisms such as Pseudomonas spp. are often isolated in water
and damp areas.
They may colonize the digestive tract of hospitalized patients.
— Selected other bacteria are a unique risk in hospitals. For instance, Legionella
species may cause pneumonia (sporadic or endemic) through inhalation of
aerosols containing contaminated water (air conditioning, showers, therapeutic
aerosols).
2 – Viruses
There is the possibility of nosocomial transmission of many viruses, including
the hepatitis B and C viruses (dentists,transfusions, dialysis, injections,
endoscopy), respiratory syncytial virus (RSV).
3- Parasites and fungi Some parasites (e.g. Giardia lamblia) are
transmitted easily among adults or children. Many fungi and other parasites are
opportunistic organisms and cause infections during extended antibiotic
treatment and severe immunosuppression (Candida albicans, Aspergillus spp.,
Cryptococcus neoformans, Cryptosporidium). These are a major cause of
systemic infections among immunocompromised patients. Environmental
contamination by airborne organisms such as Aspergillus spp. which originate in
dust and soil is also a concern, especially during hospital construction. Sarcoptes
scabies (scabies).
Reservoirs(source of
infection):
Bacteria that cause nosocomial infections can
be acquired in several ways:
The permanent or transient flora of the .1
patient (endogenous infection). Bacteria
present in the normal flora cause infection
because of transmission to sites outside
the natural habitat (urinary tract), damage
to tissue (wound) or inappropriate antibiotic
therapy that allows overgrowth.
Flora from another patient or member of .2
staff (exogenous cross-infection).
Modes of transmission of
nosocomial pathogens:
1- Direct contact: Hands of health care workers is
the most important source of infection.Transmission
prevented signifecntly by handwashing.
2- Airborne agent: Agent present in water,
waterborne agent as Legionella pneumophila
epidemic.
3- Droplets transmission as pulmonary tuberculosis
& viruses.
4- Vehicle transmission as contaminated
blood,plasma & fluids. as hepatitis C & B.
5- Food borne as E.histolytica.
6-vector transmission as malaria in Africa.
Decontamination of environment
Hand washing
Prudent use of antibiotics
Decontamination of equipment
Isolation & barrier precautions
The 5 pillars of infection
control
Thank you
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Parasitic infection