Download auto-infection

‫بسم اللة الرحمن الرحيم‬
Nosocomial Infection and Infection
Control
By
Prof. Dr. Mohamed I. Bassyouni
Summary





Sources of infection
Transmission of Infection
Patterns of Infection
Outbreaks & Epidemiological typing
Infection Control
◦ General Principles: Hospital & Community
◦ Who’s who

Hospital-acquired infection
◦
◦
◦
◦

Syndromes
Rogues’ gallery
Control of Cross-Infection
Risks from Hospital Staff
Final words
INFECTION
Definition Is entry into and multiplication
of an infectious agent (pathogen) in the
tissues of the host resulting in tissue
damage/injurious effects.
 Subclinical – unapparent.
 Clinical – apparent.
COLONIZATION
 The presence of microorganism in or on
a host with growth and multiplication but
without tissue invasion.

Sources of infection
Where do patients get their infections from...?
…in the community
Humans
Animals
(zoonoses)
clinical case
,e.g. measles
tuberculosis
clinical case
e.g. rabies
psittacosis
carrier
e.g. salmonella
leptospirosis
convalscent carrier
e.g. typhoid diphtheria
hepatitis B
symptomless
carrier e.g. typhoid,
hepatitis
Environment
auto-infection
e.g. UTI
candidiasis
food
salmonellosis,
campylobacter
soil
e.g. tetanus
vector-borne
e.g. malaria
Lyme disease
plague
water
cryptosporidiosis,
giardia, cholera
airborne
e.g. legionellosis
Sources of infection
Where do patients get their infections from...?
…in the hospital
Humans
clinical case
Cross-infection
e.g. chickenpox
streptococcal pharyngitis
wound infection
Humans
auto-infection
symptomless carrier
e.g. MRSA
(Gentamicin-resistant)
gent-resistant GNRs
food
salmonellosis
e.g. some
Staph aureus
wound infections
IVI
Environment
ventilator
e.g.Pseudomonas
disinfectants, solutions etc
eg. Pseudomonas
e.g. Staph aureus,
diphtheroids,
staph epidermidis
endoscopes
e.g. mycobacteria
H. pylori
air/dust
Staph aureus
legionella
,
Transmission of Infection
Definitions of terms by example


Salmonella gastro-enteritis
Reservoir
◦ more commonly
 animal gut flora
◦ less commonly
 human cases & carriers

Source or Vehicle
◦ food from affected animals
◦ contaminated food
Transmission of Infection
Definitions of terms by example


S. aureus wound infection
Reservoir
◦ Human nose & skin

Source or Vehicle
◦ Hands of health care workers
insert here
Patterns of Infection
Definitions

Sporadic
◦ rare infections, occurring now and then, without any particular
pattern
 e.g. gas gangrene, or Strep. pyogenes wound infections

Epidemic
◦ A sudden unexpected rise in number of infections caused by a
particular pathogen
◦ Can range from the small scale
 e.g. a few individuals
◦ up to nationwide,
 e.g. The bovine spongiform encephalopathy (BSE) also known as mad
cow disease epidemic in UK
Patterns of Infection
Definitions

Outbreak
◦ commonly used to mean a limited epidemic, e.g. in a hospital
ward

Pandemic
◦ a world-wide epidemic
◦ e.g. HIV or influenza

Endemic implies a constant significant number of
infections indefinitely
◦ e.g. methicillin-resistant S. aureus is endemic to many hospitals
Patterns of Infection
Examples
Introduction of pathogen
Epidemic infection
or outbreak
followed by
point source outbreak
with abrupt start
e.g. an outbreak of
salmonella gastro-enteritis
No. of
new
cases
outbreak sputters on due
to limited human-tohuman spread
Day
Days
Patterns of Infection
Examples
Endemic infection
continuous level of infection
e.g. S. aureus wound
infections in a hospital
predominantly due to human-to-human spread (cross-infection)
Outbreaks & Epidemiological typing

Why type organisms ?
◦ do you have an outbreak or just an increase in endemic or
sporadic infection ?
 e.g. S. aureus infections in surgical unit
◦ identification of the source or extent of outbreak
 may have legal importance, e.g. close down restaurant
◦ identification of more virulent strains,

Typing methods show whether isolates same or
different
◦ Biochemistry, Antibiogram, Phage typing, Serotyping, Molecular
methods
Infection Control
General Principles



Remove reservoir or source of infection
Interrupt transmission of infection
Increase host resistance to infection
Infection Control
in the community

Remove reservoirs & sources
◦ Human-to-human
 Case finding & treatment
 e.g. TB
 Contact tracing
 Sexually Transmitted Disease (STDs), diphtheria, TB, meningitis
◦ Animals
 Culling of infected animals
 E.g. TB, Brucella
◦ Environment
 Clean water, good housing
Infection Control
in the community

Interrupt transmission
◦ Human-to-human
 avoid overcrowding
 changes in behaviour (e.g. safe sex)
 isolation of infectious cases (e.g. from school, work)
◦ Animals & Environment
 Food hygiene, vector control, animal vaccination &
treatment, “poop-scooping”
Infection Control
in the community

Increase host resistance
◦ Improved diet
◦ Vaccination
◦ Chemoprophylaxis
 Meningitis, diphtheria, TB
Nosocomial Infections

The National Nosocomial Infections
Surveillance System (NNIS) defines a
nosocomial infection as a localized or
systemic condition 1) that results from
adverse reaction to the presence of an
infectious agent(s) or its toxin(s) and 2)
that was not present or incubating at the
time of admission to the hospital.
Hospital-acquired Infection
why worry?
10-15% of patients will get infected during a stay in
hospital
 Costs >£1 billion per year in UK
 A single large outbreak can cost thousand of billions
 Effects of nosocomial infection

◦
◦
◦
◦
◦
◦
Increased mortality & morbidity
Prolonged hospital stay
Increased drugs bill
Increased staffing costs
Demoralising for staff & patients
Decreased public confidence in hospitals & doctors
Why is hospital-acquired infection different from
community-acquired infection?

Many patients have impaired immunity
◦ After anti-cancer chemotherapy
◦ After transplants
◦ Extremes of age

Many patients have impaired normal physiological defences
◦ Breaches in skin
◦ Implanted foreign bodies (biofilms)
◦ Impaired phsyiology (Peristalsis, mucociliary escalator)

Many vulnerable patients in close proximity to each other for
prolonged periods of time
Why is hospital-acquired infection different from
community-acquired infection ?

There is a distinct hospital flora
◦ "ordinary" pathogens
 e.g pnemococci, E. coli, S. aureus, can all cause disease both inside and outside
hospital
◦ opportunists
 only cause infection in patients with impaired immunity
 e.g Serratia marsecens, Xanthomonas maltophilia, S. epidermidis, Corynebacterium
jeikeium
◦ multi-resistant bacteria
 overlap with previous groups
 selected for in a darwinian fashion by antibiotic usage in hospitals
 include opportunists which are inherently multi-resistant (e.g. Xanthomonas
maltophilia) and multi-resistant varieties of common organisms, e.g. MRSA,
gent-resistant E. coli
Infection Control
in hospital

Remove reservoirs & sources
◦ Human-to-human
 Discharge infectious patients, e.g. with MRSA
 Treat & decontaminate patients
◦ Environment
 Control of Legionella
 Ward hygiene & cleaning
 Hospital design
Infection Control
in hospital

Interrupt transmission
◦ Human-to-human





Hand washing
Ward routine (e.g. wet mopping)
Aseptic technique
Sterilisation & disinfection
Isolation procedures
◦ Environment
 Food hygiene, pest control, theatre design
Infection Control
in hospital
 Increase
host resistance
◦ Good nutrition [e.g. total parenteral nutrition
(TPN) in Intensive Treatment Unit (ITU)].
◦ Restore normal physiology as quickly as
possible
 Remove lines, catheters ... etc
◦ Vaccinate (e.g. hepatitis B)
◦ Correct underlying defects
 E.g. control diabetes
◦ Stimulate immunity (e.g. Granulocyte macrophage colonystimulating factor GM-CSF)
Infection Control
who’s who in hospital




Infection Control Doctor
Microbiologist
Infection Control Nurses
Infection Control Committee
◦ Formulate policies
 waste disposal, theatre design, food hygiene ... etc
◦
◦
◦
◦
Surveillance of infection
Management of outbreaks
Staff education
Power to close wards and even whole hospitals

The committee of a large hospital should have representatives from all the
major departments which may be concerned with the control of infection.

It should:-

1- Discuss any problems brought to them by infection control doctor,
nurse or other members of the committee.

2- Take the responsibility for major decisions.

3- Be given reports on current problems and on incidence of infection.

4-Arrange interdepartmental co-ordination and education in the control of
infection.

5- Introduce, maintain and when necessary modify policies.

6- Advise on the selection of equipment for the prevention of infection
(e.g. sharps disposal boxes, etc.).

7- Make recommendations to their committees.
Action at the time of an Outbreak
of Infection

1- Arrangements for the clinical care of patients.

2- Adequate channels for communication should be set up and a decision
made as to who will be responsible for the communication with the media.

3- Assessment of the situation should be made.

4- Isolation of infected patients.

5- Introduction of additional control of infection techniques in affected
wards, closure of a ward and thorough cleaning after discharge of the last
patient before re-opening.

6- The allocation of beds.

7- An epidemiological survey should be undertaken to provide evidence of
time and place where infection was acquired.

8- Surveillance of contacts-who may be incubating the disease ( this
include clinical surveillance, laboratory screening and typing ).

9- Bacteriological search for source of infection; examination of all staff and
patients for carriage to see whether the same phage type of S. aureus is
isolated from all infections.

10- Survey of methods, equipment and buildings.

11- The infection control or occupational health nurse will discuss the
situation with the head of the departments to relieve anxieties and indicate
any necessary procedures.

12- The requirement for assistance should be assessed at each meeting and
advice sought as necessary.
Why do we need Typing ?
1- Prompt and appropriate treatment.
 2- Improved patient outcomes.
 3- Reduced length of hospital stays.
 4- Improved cost-effectiveness.
 5- Identify local outbreaks.
 6- Identify epidemic/endemic clones.
 7- Understand epidemiology of diseases.
 8- Understand microbial evolution.

How to do Typing ?


1- Choose the microbial isolates which need
typing.
2- Conditions for all isolates should be the same;
a- Same culture age and type.
b- All of them should be processed together.
c- In the same media manufacturer batch.
d- With the same reagent manufacturer batch.
e- In the same incubator.
The typing methods


PHENOTYPIC METHODS
- Susceptibility testing the study of the different antimicrobial agents.

Dilution Susceptibility tests involves inoculating media containing
different concentrations of the drug

broth or agar with lowest concentrations showing no growth is the
Minimal inhibitory concentration (MIC).

If broth used tubes showing no growth can be subcultured into
drug-free medium, broth which microbe can’t be grown is the Minimal
Bactericidal concentration (MBC).

Disk Diffusion Tests; disks impregnated with a specific drugs are
placed on agar plates inoculated with the tested microbe. Drugs diffuses
from the disk into the agar, establishing concentration gradient, we
observe clear zones (no growth) around the disks.

Kirby-Bauer agar disk diffusion; Paper disks containing an antibiotic
is placed on lawn of bacteria, then incubated overnight. The diameter of
the zone inhibition is inversely related to MIC (used to establish
interpretive breakpoints). Standardized for commonly isolated rapidly
growing organisms.

E-test :- Strips containing a gradient of antibiotics are placed on
lawn of bacteria and incubating overnight. MIC is determined at a
point where a zone of inhibition intersects scale on strip. In
general MIC quantitative result is better than qualitative result
(sensitive or resistant) because it gives a wide range of results.

- Phage typing is the effect of different bacteriophages on the
bacteria.

- Biochemical typing Is the effect of biochemical reaction from the
bacteria.

Coagulase typing ( positive or negative ).

- Serological typing is the study of the different antigenic types of
bacteria e.g. the most common serotypes of Neisseria
meningitidis are A,B.C, W135 and Y.

GENOTYPING METHODS

- Pulse filled Gel Electrophoresis (PFGE). Is the study of the
different filled bacterial DNA by cut it by enzymes making
different bands for the bacteria.

- Polymerase Chain Reaction (PCR) is the study of different
targets (genes) in bacterial DNA.
Hospital-acquired Infection
Syndromes

Nosocomial UTI
◦ ~30% of hospital infections
◦ Usually catheter associated
 Asymptomatic colonisation common
◦ Treatment of clinical infection often requires
catheter removal
 BUT only under antibiotic cover!
Hospital-acquired Infection
Syndromes

Chest infection
◦ ~20% of nosocomial infections
◦ Gram-negative pneumonia
 Problem in critically ill & immunocompromised patients
◦ Legionellosis
 Vigilance is necessary for early detection of outbreaks
 Control by
 raising the hot water temp
 regular cleaning & inspection of water & air-cooling systems
Hospital-acquired Infection
Syndromes

Wound Infections
◦ ~20% of nosocomial infections
◦ Rates vary depending on whether “clean” or
“dirty” surgery

Blood-stream Infections
◦ ~30% of nosocomial infections
◦ Especially device-associated infection
◦ Treatment: remove the foreign body
Hospital-acquired Infection
Rogues gallery

Methcillin-resistant Staphylococcus aureus
◦ MRSA
◦ Infection Requires vancomycin treatment
◦ Colonisation requires isolation, decontamination with mupirocin
and betadine

Vancomycin-resistant enterococci
◦ VRE, includes E. faecalis and E. faecium
◦ Low grade pathogens
◦ If also multi-drug resistant treatment can be difficult
 E. faecium but not E. faecalis treatable with quinupristin & dalfopristin
(Synercid)
Hospital-acquired Infection
Rogues’ gallery

Clostridium difficile
◦ Causes Antibiotic-associated colitis
◦ Can cause outbreaks in hospitals
◦ Patients should be isolated

Gentamicin-resistant GNRs
◦ Require treatment with expensive drugs such as amikacin and
imipenem
◦ Patients should be isolated
◦ Can cause outbreaks e.g. on oncology wards or in ITU

Fungal infection
◦ Aspergillus fumigatus and Candida albicans can cause nosocomial
outbreaks
Control of Cross-Infection

Handwashing is paramount!
◦ even for Consultants!
◦ wash your hands before & after
examining patients, especially if
you look at undressed wounds
◦ Alcoholic hand rubs may
provide a convenient alternative
to soap and water, especially
where sinks are in short supply
or during an outbreak
Control of Cross-Infection

Isolation of infectious patients
◦ whenever you admit or assess a patient think:
 does this patient need to be isolated?
◦ general precautions
 Side-room isolation (or cohort nursing or isolation ward)
 Hand-washing on entry & exit
 Use of aprons and gloves
◦ consult
 microbiologist or infection control nurse for advice
 infection control manual for isolation protocols
 contains advice on meningitis, D&V, open TB, MRSA, hepatitis, HIV, and lots more
besides - everything from Lassa to lice!!

Prophylaxis
◦ e.g. of contacts of chickenpox, diphtheria, meningitis
Risks from Hospital Staff
 • Take
Care Of Yourself!
◦ Your first responsibility is to your patients not your colleagues
 Do not work if you have diarrhoea, or a flu-like illness, a sore throat, or if you
may be incubating a viral illness such as measles, rubella, chickenpox!

• Be Considerate To Lab Staff!
◦ Don't send specimens to the lab without proper packing,
 leaking and / or blood-stained specimens are not acceptable!!!
◦ Label hazardous specimens
Summary





Sources of infection
Transmission of Infection
Patterns of Infection
Outbreaks & Epidemiological typing
Infection Control
◦ General Principles: Hospital & Community
◦ Who’s who

Hospital-acquired infection
◦
◦
◦
◦
Syndromes
Rogues’ gallery
Control of Cross-Infection
Risks from Hospital Staff
...and some final words on
Hospital Infection Control...


An extract from the work
book of Dr Fester, aged 24
and a half, newly qualified
house officer...
50 lines as punishment for
poor hand hygiene

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients

I promise to wash my hands between patients...
file:///C:/Users/User/Documents/au
thorGEN%20Projects/3.%20preven
tion1_infcontrol/aP%20Lite%20Fla
sh/index.html
Thanks