Transcript Pathogens Important to Infection Prevention and Control

Pathogens Important
to Infection
Prevention and
Control
1. List special pathogens of interest to
IP&C, and for each, describe the impact
on the IP&C programme
2. Explain how antibiotic-resistant bacteria
cause problems in healthcare
3. Outline preventive measures for a given
special pathogen
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Learning objectives
2
• 90 minutes
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Time involved
3
• Everyday problem microorganisms for infection
prevention and control include:
• Mycobacterium tuberculosis
• Clostridium difficile
• Antibiotic resistant organisms
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Special pathogens
• MRSA, VRE
• Gram-negative multiply resistant organisms
• Enterobacteria (Escherichia coli, Klebsiella pneumoniae)
• Pseudomonas aeruginosa
• Acinetobacter baumanii
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• Mycobacterium tuberculosis causes tuberculosis (TB)
• TB affects 1/3 of the world’s population
• 9.4 million new cases in 2008
• 1.8 million deaths in 2008
• Leading cause of death in people living with human
immunodeficiency virus (HIV)
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Mycobacterium tuberculosis
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• Spread by the airborne route when someone
with active disease and positive sputum
smear coughs, talks, sneezes, or spits
• Bigger droplets spread up to 1 m, smaller
spread by air
• Bacteria inhaled into lungs
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Transmission and
pathogenesis of TB - 1
• In lung tissue and lymph nodes the bacteria grow
and reproduce
• Can travel to any location in the body
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• Latent TB – bacteria contained in the body
• 10% of people with latent TB will develop active
disease
• Most commonly affected organ - Lungs
• Untreated, a person with active disease can infect
10 to 15 people a year
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Transmission and
pathogenesis of TB - 2
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• Pulmonary TB (active)
• Cough with thick cloudy, sometimes bloody
sputum
• Tiredness
• Appetite loss/unexplained weight loss
• Night sweats
• Fever/chills
• Shortness of breath
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Clinical forms
• Extra pulmonary TB
• Signs and symptoms vary with site of infection
• Other common sites include central nervous
system, bones, joints, and genitourinary system
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• Weakened immune
system
• Contact with
someone with active
TB
• Caring for active TB
patients
• Living or working in
crowded conditions
with someone with
active TB
• e.g., prisons, nursing
homes, homeless
shelters
• Poor access to
healthcare
• Alcohol or drug
abuse
• Travel to places
where TB is endemic
• Being born in a
country where TB is
endemic
• Some medications
for rheumatoid
arthritis
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Risk Factors
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• BCG strain of Mycobacterium bovis is used
as a vaccine
• BCG is given to infants (best soon after
birth)
• Vaccination against TB does not protect
against infection but only against severe
forms of disease
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Vaccination
• Meningitis
• Disseminated TB (miliary)
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• Chest x-ray
• Sputum smear for acid fast bacilli
• Tuberculin skin test (TST)
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Diagnosis & Management
• Can take up to 3 months for those newly
exposed to develop positive test
• May be falsely positive because of BCG
vaccination
• Interferon gamma release assays (IGRA) in
vaccinated persons
• Culture (can take up to six weeks) and
sensitivity test
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Management of Exposure
• Confirmation of positive infection
• Medical evaluation to determine follow up
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Management & Treatment
Treatment of patients
• Treatment for latent or active TB should follow
World Health Organization recommendations
• Incomplete treatment can cause resistance
• Adherence to therapy is critical
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Engineering controls
• Negative pressure rooms
• High efficiency particulate air (HEPA) filtration
system
• Enhanced ventilation
• Ultraviolet irradiation (only in empty room)
• Sunlight exposure
• Open window (last resort if no other options)
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IP&C Measures
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HEPA
filter
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Negative presssure
room
Air flow
Patient with active TB isolated in
negative pressure room
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Administrative Controls
• Identify patients with signs and
symptoms of TB
• Additional precautions for
patients suspected to have active
TB
• Prompt treatment
• Vaccination of healthcare
personnel
• Respiratory etiquette
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IP&C Measures - 1
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Personal Protective Equipment*
• N-95 fit tested masks for healthcare workers
• If not available, then surgical masks
• Surgical masks for patients leaving their rooms
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IP&C Measures - 2
* Typically used for pulmonary TB if the patient is
expectorating or has an open lesion
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• Despite the high global impact of TB, it is
treatable and preventable
• Occupation exposures remain a significant
risk for healthcare workers
• IP&C measures are needed to decrease
exposures to patients and healthcare
workers
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Conclusion
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• There is a global increase in Clostridium
difficile infections (CDI) and outbreaks
over the past 10 years; however the
illness is not a problem in all countries
• CDI primarily occurs in those patients
exposed to antibiotics in healthcare
facilities
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Clostridium difficile: Background
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• A Gram-positive spore forming anaerobic bacillus
• Widely distributed in the environment
• In its vegetative state
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Pathology - 1
• Produces toxins
• Can be killed by antibiotics
• Spore form
•
•
•
•
Dormant
No toxin production
Resistant to antibiotics and disinfectants
Can persist for months in the environment
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• Produces 2 toxins
• Toxin A and Toxin B
• Bind to intestinal epithelial cells causing
inflammation and diarrhea
• Toxins are cytotoxic and enteropathic
• Alteration of the gut flora by antibiotics
an important risk factor (decrease of
normal gut flora)
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Pathology - 2
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• Mild disease
• Non-bloody diarrhoea, often mucoid and foul
smelling, cramping, nausea, dehydration, low
grade fever, leukocytosis
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Clinical Significance
• Severe disease
• Colitis, watery diarrhoea, abdominal pain,
fever, nausea, abdominal distension,
pseudomembranes in the gut, toxic mega
colon, death
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• Increased incidence of B1/NAP1/027 strain
• Causes severe disease
• More resistant to standard therapy
• More likely to relapse
• Associated with higher mortality
• 16x more toxin A; 23x more toxin B
• Related to excessive use of certain
drugs/antibiotics
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New Strain
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• Approximately 3-5% of healthy adults and
20 to 40% of hospitalised patients may be
colonised
• Colonised patients generally are not
symptomatic
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Colonisation
• May be a potential reservoir for transmission
• Evidence suggest spores on the skin of
asymptomatic patients can contaminate
the hands of the healthcare worker
• No recommendations to treat carriers nor
to perform admission screening
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Patients at Risk
Admission Screening
Route of Transmission
Isolation Precautions
Accommodation
Documentation (flagging of patients)
Environmental Cleaning
Discontinuation of Precautions
Follow-up of Contacts
Point Prevalence
Additional Outbreak Measures
Previous antibiotic use
Severe underlying illness
Prolonged hospital stay
Advanced age
Gastrointestinal surgery/manipulation
History of irritable bowel disease
Patients on proton pump inhibitors
No
Contact
Yes
Single room preferred
Separate toileting facilities
May be of benefit to implement a system to designate patients known to be
colonised or infected for early notification on readmission
Routine cleaning with attention to high touch surfaces and use of a sporicidal
agent
Consider double-cleaning for outbreak situations
No diarrhoea for at least 48 hours
No
No
Strict cleaning of multi-use equipment between patients
Dedicated patient equipment to positive cases
Education of staff, patients and visitors
Auditing of outbreak unit/area including hand hygiene,
isolation
practices and environmental cleaning
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Transmission and Control Measures
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• Discontinuation of all antibiotics in a
symptomatic patient (except for CDI)
• Facility-wide antibiotic control policies
• Early notification of patients with
diarrhoea to the IC team
• Not recommended
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Additional Control Measures
• Routine identification of carriers
• Repeat testing post treatment for clearance
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Antibiotic Resistant
Microorganisms
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Methicillin Resistant
Staphylococcus aureus (MRSA)
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• Staphylococcus aureus is a Gram-positive
bacteria
• 30% of people are permanently colonised
• Nose
• Pharynx
• Perineum
• Transient colonisation occurs, mainly on
hands
• Colonisation although harmless,
increases the risk of infection and
transmission
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Background
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• First a problem in 1960s
• Globally has reached epidemic
proportions
• Both community associated (CA) and
healthcare associated (HA) strains of
MRSA
• Rates vary by
• Country
• Region
• Individual healthcare facility
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Clinical Significance of MRSA
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Patients at Risk
Admission Screening Sites
Route of Transmission
Isolation Precautions
Accommodation
Documentation (flagging of patients)
Environmental Cleaning
Discontinuation of Precautions
Follow-up of Contacts
Point Prevalence
Additional Outbreak Measures
Previous antibiotic use
Severe underlying illness
Prolonged hospital stay
Previous contact with medical facility
Use of invasive procedures
Close proximity to a patient colonised or infected with MRSA
Yes, based on patient risk factors
Nares, rectal, wounds, exit sites
Contact (plus droplet for symptomatic patients with pneumonia)
Yes
Single room preferred
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MRSA Transmission and Control Measures
May be of benefit to implement a system to designate patients known to be colonised
or infected for early notification on readmission
Routine cleaning with attention to high touch surfaces
Unresolved issue:
Some institutions use the following criteria:
Negative results from all colonised/infected body sites- 3 consecutive cultures taken
at least one week apart in the absence of antibiotic therapy
Note:
Re-colonisation is known to occur so on-going monitoring is recommended
Consider maintaining isolation precautions in an outbreak setting
Two sets of specimens taken on different days with one taken a minimum of 7 days
after the last exposure, especially in an outbreak setting
In an outbreak setting:
Conduct serial (e.g., weekly) unit specific point prevalence cultures to determine if
transmission has decreased or ceased
Consider discharge and/transfer screening of patients until transmission has
decreased or ceased
Strict cleaning of multi-use equipment between patients
Dedicated patient equipment to positive cases
Education of staff, patients and visitors
Auditing of outbreak unit/area including hand hygiene, isolation practices
and environmental cleaning
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• Vancomycin is drug of choice for treating
MRSA infections
• Staphylococcus aureus with decreased
(intermediate) susceptibility to
vancomycin = VISA
• Staphylococcus aureus with resistance
genes Van A or Van B = VRSA
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VISA and VRSA
• So far only few isolates in different parts of the
world
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Vancomycin Resistant
Enterococcus (VRE)
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• Enterococci are normal gut bacteria
• May also be present in the oropharynx, vagina,
or on skin
• Causes serious bacterial infections
•
•
•
•
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Background
Wound infections
Urinary tract infections
Endocarditis
Sepsis
• Often resistant to ampicillin (the drug of choice);
infections then treated with glycopeptides
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• VRE is enterococcus that is resistant to the
glycopeptide vancomycin
• First isolated in the 1980’s
• Spread globally causing asymptomatic
colonization, infections, and outbreaks
• The prevalence of VRE varies worldwide
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VRE Epidemiology
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• Clinically relevant strains carry Van A or Van
B resistance genes
• Limited antibiotics to treat VRE infections
• Transfer of resistance genes to other
microorganisms such as MRSA is a great
concern
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Clinical Significance
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Patients at Risk
Admission Screening Sites
Route of Transmission
Isolation Precautions
Accommodation
Documentation (flagging of patients)
Environmental Cleaning
Discontinuation of Precautions
Follow-up of Contacts
Point Prevalence
Additional Outbreak Measures
Previous antibiotic use
Severe underlying illness
Prolonged hospital stay
Previous contact with medical facility
Use of invasive procedures
Close proximity to a patient colonised or infected with VRE
Yes, based on patient risk factors. Rectum
Contact
Yes
Single room preferred
Separate toileting facilities
May be of benefit to implement a system to designate patients known to be colonised or infected
for early notification on readmission
Routine cleaning with attention to high touch surfaces
Consider double cleaning in outbreak situations
Unresolved issue:
Some institutions use the following criteria:
Negative results from all colonised /infected body sites- 3 consecutive cultures taken at least one
week apart in the absence of antibiotic therapy
Note: Re-colonization is known to occur so on-going monitoring is recommended. Consider
maintaining isolation precautions in an outbreak setting
Two sets of specimens taken on different days with one taken a minimum of 7 days after the last
exposure, especially in an outbreak setting
In an outbreak setting:
Conduct serial (e.g., weekly) unit specific point prevalence cultures to determine if transmission
has decreased or ceased
Consider discharge and/transfer screening of patients until transmission has decreased or ceased
Strict cleaning of multi-use equipment between patients
Dedicated patient equipment to positive cases
Education of staff, patients and visitors
Auditing of outbreak unit/area including hand hygiene, isolation practices
and
environmental cleaning
December 1, 2013
VRE Transmission and Control Measures
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Multi-Drug Resistant GramNegative Microorganisms
(MDRGN)
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• The “Enterobacteriaceae” family of bacteria are
a normal part of the gastrointestinal flora
• The most frequent isolates are:
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MDRGN - 1
• Escherichia coli
• Klebsiella pneumoniae
• Serratia marcescens
• Enterobacter species
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Escherichia coli and Klebsiella pneumoniae can
have extended spectrum beta-lactamase (ESBL)
enzymes that cause resistance to beta-lactam
antibiotics including:
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Mechanisms of Resistance
• Penicillins
• Cephalosporins
• Cephamycins
• Monobactams
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• There are various types of ESBLs including
• TEM
• SHV
• CTX-M
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Epidemiology of ESBL strains
• ESBLs were first detected in Europe in 1980s
• Surveillance data from several surveillance
systems indicate high rates of ESBLs in many
parts of the world including USA, Canada,
Europe, China, India and Latin America
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• Carbapenem antibiotics are the treatment of
choice for serious infections due to ESBLproducing bacteria
• Carbapenem Resistant Enterobacteriaceae (CRE)
has also been reported
• Carbapenemases of importance include KPC,
VIM, OXA and NDM-1
• CREs have been reported in many areas of the
world and have also been associated with
outbreaks
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Epidemiology of CRE
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• The following bacteria are present in
aquatic environments
• Acinetobacter baumannii
• Pseudomonas aeruginosa
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MDRGN - 2
• Opportunistic pathogens in humans
• A major cause of healthcare-associated
infections
• Septicemia
• Ventilator-associated pneumonia
• Urinary tract infections
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• These microorganisms have intrinsically
lower susceptibility to antibiotics
• Acquiring additional resistance genes (ESBL
genes, other genes for resistance to beta
lactam antibiotics, resistance genes for
aminoglycosides and fluoroquinolones) very
often means that they are
• susceptible only to carbapenems or
• colistin or
• resistant to all antibiotics (panresistant)
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MDR P. aeruginosa and MDR A. baumannii
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• MDRGN (including ESBLs, CREs, MDR PA and
MDR AB) pose a significant treatment
challenge including
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Clinical Significance
• Increased length of stay
• Increased mortality
• Increased cost
• Contributes to the global crisis of
antimicrobial resistance
• Control requires an aggressive world-wide
strategy
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Patients at Risk
Admission Screening Sites
Previous antibiotic use
Severe underlying illness
Prolonged hospital stay
Previous contact with medical facility
Contact with a facility with known outbreaks with MDRGN organisms
Yes, based on local epidemiology and patient risk factors. Rectum
Isolation Precautions
Contact
(plus droplet for symptomatic patients with pneumonia)
Yes
Accommodation
Single room preferred
Documentation (flagging of patients)
May be of benefit to implement a system to designate patients known to be colonised or
infected for early notification on readmission
Routine cleaning with attention to high touch surfaces
Route of Transmission
Environmental Cleaning
Discontinuation of Precautions
Follow-up of Contacts
Point Prevalence
Additional Outbreak Measures
December 1, 2013
MDRGN Transmission and Control Measures
Unresolved issue:
Some institutions use the following criteria:
Negative results from all colonised /infected body sites- 3 consecutive cultures taken at
least one week apart in the absence of antibiotic therapy
Note:
Re-colonisation is known to occur so on-going monitoring is recommended
Consider maintaining isolation precautions in an outbreak setting
Based on local epidemiology and patient risk factors
In an outbreak setting:
Conduct serial (e.g., weekly) unit specific point prevalence cultures to determine if
transmission has decreased or ceased
Consider discharge and/transfer screening of patients until transmission has decreased or
ceased
Strict cleaning of multi-use equipment between patients
Dedicated patient equipment to positive cases
Education of staff, patients and visitors
Auditing of outbreak unit/area including hand hygiene, isolation
practices and environmental cleaning
45
• IP&C measures vary based on institutional
setting and available resources
• Hand hygiene should be a routine part of
patient care in all settings
• Additional precautions may be considered
depending on the pathogen, the
institutional setting and outbreak
circumstances
December 1, 2013
Management of Pathogens in
Low Resource Countries
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• Antimicrobial resistance is a world-wide public
health problem
• Solutions require a multi-faceted approach
• Improving behaviours is essential
• Global awareness and surveillance is required
• Implementation of appropriate IP&C practices
and antimicrobial stewardship processes may be
beneficial
December 1, 2013
Conclusion
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• Tuberculosis and multi-drug resistant
bacteria are important infection prevention
and control issues
• Many have developed resistance to
antimicrobials making them less effective
• Control measures vary by organism, setting
and resources
December 1, 2013
Key Points
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• Apisarnthanarak A, Fraser VJ. Feasibility and efficacy of
infection control interventions to reduce the number of
nosocomial infections and drug resistant microorganisms in
developing countries: what else do we need? CID
2009;48:22-24
• EARS-Net.
http://www.ecdc.europa.eu/en/activities/surveillance/EARS
-Net/Pages/index.aspx
• WHO 2010. Global tuberculosis control
http://www.who.int/mediacentre/factsheets/fs104/en/inde
x.html
• Special pathogens, in Damani N. Manual of infection
prevention and control, 3rd ed. Oxford University Press,
Oxford, 2012:183-249.
December 1, 2013
Further reading
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1. When a patient with active tuberculosis has to leave
the isolation room for tests, s/he has to wear a N95
mask. T/F?
2. Admission screening for MRSA encompasses the
following specimens:
a.
b.
c.
d.
December 1, 2013
Quiz
Nares alone
Nares, wounds, exit sites
Nares, wounds
Nares, exit sites
3. ESBL genes are transmitted by plasmids and are
restricted to Enterobacteriaceae. T/F?
50
• IFIC’s mission is to facilitate international networking in
order to improve the prevention and control of
healthcare associated infections worldwide. It is an
umbrella organisation of societies and associations of
healthcare professionals in infection control and related
fields across the globe .
• The goal of IFIC is to minimise the risk of infection within
healthcare settings through development of a network of
infection control organisations for communication,
consensus building, education and sharing expertise.
• For more information go to http://theific.org/
December 1, 2013
International Federation of
Infection Control
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