Hospital Outbreaks
Allison McGeer
Mount Sinai Hospital
416-586-3118
amcgeer@mtsinai.on.ca
Outbreaks
• Anything out of the ordinary
• An increase in the occurrence of a
complication or disease above the
background rate
• A statistically significant increase in the
incidence of an infection
Why are hospitals a problem?
PATHOGENS
– They concentrate virulent pathogens
ACCESS
– By hands on care, they allow transmission of these
pathogens
– By devices & parenteral therapy, they permit access
HOSTS
– They admit susceptible hosts (elderly,
immunocompromised)
– They make them more susceptible (chemotherapy,
surgery)
Hospital Outbreaks
• 1 in 8 patients in Canadian hospitals acquire an
infection as a result of their hospital stay
– 5-10% of these are part of outbreaks
• Rate: 1/10,000 admissions (Wenzel, 1981)
1/12,000 admissions (Haley, 1985)
at least an equal number of “clusters”
Outbreaks to be prepared for:
• MRSA/VRE; S. aureus (nurseries); S.
pneumoniae; GAS
• P. aeruginosa, Serratia, Salmonella;
resistant gram negs (ICU)
• Legionella, Mycobacteria, C. difficile
• Scabies
• Candida, Aspergillus
• Influenza, Hepatitis A/B/C, SREV, Adeno
Outbreaks to be prepared for:
• MRSA/VRE; S. aureus (nurseries); S.
pneumoniae; GAS
• P. aeruginosa, Serratia, Salmonella;
resistant gram negs (ICU)
• Legionella, Mycobacteria, C. difficile
• Scabies
• Candida, Aspergillus
• Influenza, Hepatitis A/B/C, SREV, Adeno
“Other” hospital outbreaks
• E. coli O157:H7 in a salad served to patients, and
in cafeteria
• Legionella pneumophila in water supply
• Pseudomonas aeruginosa from water/sinks
• Ralstonia picketii from contaminated normal
saline
• Aspergillus fumigatus from an air conditioner
• Serratia marcescens blood infections from
propofol
• Candida spp. from vacuum seals in equipment for
preparation of TPN
Hospital vs. Community Outbreaks
• Reservoir/propagation
– Reservoir is people (usually patients)
– Propagation is person to person
• We provide medical care to patients, as well
as outbreak management
– Easier to get medical/laboratory information
– Differences between goals more evident
Preparing for outbreaks Prevention
• Physical structure
•
•
•
•
Private rooms
Adequate space – between patients, for cleaning
Adequate ventilation
Enough handwashing sinks, well-placed
• Design in purchased equipment
•
•
•
•
Glucometers
Needleless IV systems
Monitors for negative pressure rooms
Machines for cleaning/disinfecting endoscopes/
endoscopes themselves
• Cleaning/disinfection/sterilization
• Adequate policies
• Adherence to policies
Preparing for outbreaks Prevention
• Handwashing
– Accessibility
– Programs for compliance
• Education
–
–
–
–
Aseptic technique
Handwashing
Isolation precautions
Surveillance/reporting
Preparing for outbreaks
• Detection
– surveillance, awareness
– culture, lab processing protocols
– thresholds, time frames
• Preservation of samples/isolates (typing)
Preparing for outbreaks
• Lines of communication
– awareness among administrative staff
– media relations
• Funding
– microbiology lab services
• Policies for outbreak management
Goals of outbreak
investigation/management
Outbreak types
Investigation
• Cause unknown
• Control uncertain
• Disease severe/many
cases
• Something to learn
Management
• Cause is known
• Exposure/transmission
known
• Control measures effective
• Small number/non-severe
cases
• “Nothing to learn”
Outbreak investigation
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•
•
•
•
•
•
•
•
Verify diagnosis
Confirm the outbreak
Develop a case definition
Obtain descriptive epidemiology
Develop a hypothesis
Test the hypothesis
Refine hypothesis/additional studies
Implement control and prevention measures
Communicate findings
Hospital outbreak investigation
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•
•
•
•
•
•
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Verify diagnosis
Confirm outbreak
Perform literature review/call experts
Develop a case definition
Obtain descriptive epidemiology
Open lines of communication
Implement control measures
Consider definitive investigation
Initial Investigation
1 Verify diagnosis
2 Confirm the existence of a problem
- confirm the diagnosis
- review existing data (surveillance records,
interviews, microbiology records, charts)
3 Perform a literature review/ call experts
- reservoirs, mode of transmission
- things that went wrong
Initial Investigation
4 Develop a case definition
-
microbiology
other lab, radiology
clinical signs/symptoms
other (e.g. skin testing for TB)
set time/place parameters
5 Identify, count, describe cases
-
line listing
time/place person
describe nature and severity
plot epidemic curve
Initial Investigation
6 Open lines of communication
- consider media strategy
- ensure all isolates/potential isolates are saved
7 Implement control measures
- enforce existing measures
- supplement
Initial Investigation
8 Consider definitive investigation
- formulate hypotheses
- case control/cohort studies
- cluster analysis
Problem #1
• 3 candidemias on 14th level at MSH in one
month
• 14th level is gi medicine/general surgery
– 68 beds
– large oncology/IBD population
– 25 pts per month on TPN
Problem #2
Invasive GAS disease, LTCFs
Number of cases
30
25
20
15
10
5
0
92
93
94
95
96
Year
97
98
99
2000
Other presentations/articles
• http://www.idready.org/slides/03outbreakslides.pdf
• http://www.dsf.health.state.pa.us/health/lib/
health/Outbreak_Investigation.ppt
• http://www.wvdhhr.org/idep/PPTs/Outbreak
Investigation.ppt
• http://www.cdc.gov/ncidod/eid/vol4no1/rein
gold.htm