Transcript Nosocomial outbreaks Agnes Hajdu EpiTrain III, 24.08.2006 Jurmala, Latvia Content • • • • Nosocomial infections Health care setting Antimicrobial resistance Nosocomial outbreaks – – – – History Characteristics Outbreak database Detection, Investigation • An example: Dent-O-Sept • Summary.

Nosocomial outbreaks
Agnes Hajdu
EpiTrain III, 24.08.2006
Jurmala, Latvia
Content
•
•
•
•
Nosocomial infections
Health care setting
Antimicrobial resistance
Nosocomial outbreaks
–
–
–
–
History
Characteristics
Outbreak database
Detection, Investigation
• An example: Dent-O-Sept
• Summary
Nosocomial infection
…hospital-acquired infection, health-care
associated infection…
• Infection acquired in the hospital due to
exposure to the pathogen in the hospital
• Development of infection after 48 hours of
hospital admission (CDC)
Burden of nosocomial infections
• Increased morbidity, mortality
– 10% of in-patients acquire an infection in the
hospital
• Increased costs
– Prolonged hospital stay, additional medical
procedures and treatment
• 30% preventable
Health care setting
•
•
•
•
Devices: endoscope, catheter, ventilator..
Medical procedures: surgery..
Medical personnel: doctors, nurses..
Patient: immunocompromised, susceptible
maybe
the source as carrier of pathogen
• Dangerous residents: MRSA, VRSA, VRE, ESBL*, C.
difficile ribotype 027
*methicillin-/vancomycin-resistant S.aureus; vancomycin-resistant Enterococcus; extended
spectrum beta-lactamases
Patients at risk
• Immunocompromised patient
– Malignancy, immunosuppressive treatment,
HIV infection
• Other factors
– Severe underlying disease, age, obesity
• Intensive care units
– Medical, surgical, neonatal, burn units
Antimicrobial resistance
1945 – Penicillin
1948 – Penicillin-resistant S.aureus
1959 – Methicillin
1961 – Methicillin-resistant S.aureus
1998 – Vancomycin-resistant S.aureus
• Use, overuse and wrong use of antibiotics
• Possible to reverse, but it takes time
• Knowledge
Attitude
Behaviour
What can be worse
than a nosocomial infection?
A Nosocomial Outbreak!!!
An unusual increase in the number of
nosocomial infections (time, place, person)
History of nosocomial outbreaks
• First well-documented outbreak
– Puerperal (child-bed) fever in a hospital in Vienna, 1847
– Ignác Semmelweis, Hungarian physician gathered and
analysed mortality data
– Autopsy room
Maternity wards
– Handwashing intervention (chlorine solution)
• Modern epidemiology
– S. aureus hospital outbreaks worldwide, 1950s
– CDC projects from 1970s
– Intensive research from 1990s
1847
2006
Nosocomial outbreaks - examples
• Unusual transmission
– ESBL Klebsiella pneunomiae
– Maternity wards, contaminated ultrasonography gel (France,
1993)
• Rare pathogen
– Malassezia pachydermatis
– Neonatal ICU, associated with colonization of health care workers’
pet dogs (US, 1995)
• Emergence of more virulent strain
– C. difficile ribotype 027
– Increased severity of diarrhoea, recent outbreaks in US, Canada,
Netherlands, England
Nosocomial outbreak database
• Database providing information to facilitate
interventions
• A learning tool
– What kind of data to collect? Control selection?
• Search by pathogen, ward type etc.
• Osaka University, Japan
• http://health-db.net/infection/top1.htm
Characteristics of nosocomial outbreaks
•
•
•
•
•
•
Location
Type of infection
Pathogens
Source
Mode of transmission
Preventive/control measures
Gastmeier et al. How Outbreaks Can Contribute to Prevention of
Nosocomial Infections: Analysis of 1022 Outbreaks. Infection Control
and Hospital Epidemiology; 2005 26(4);357-361
Gastmeier et al.
Location
• Hospital – 83%
– 50% in intensive care units
• Outpatient care – 12%
• Nursing home – 5%
Special problems:
– Hospital staff with part-time job in nursing
homes (transmissing pathogens in both ways)
– Nursing home: no infection control personnel,
underreporting of outbreaks, gastroenteritis,
scabies
Gastmeier et al.
Type of infections
•
•
•
•
•
•
•
•
Bloodstream – 37%
Gastrointestinal* – 29%
Pneumonia – 23%
Urinary tract – 14%
Surgical site – 12%
Other lower respiratory – 10%
Central nervous system – 8%
Skin and soft tissue – 7%
*Probable underreporting
Gastmeier et al.
Most frequently reported pathogens*
Nosocomial infections
Nosocomial outbreaks
•
•
•
•
•
•
•
•
•
•
•
•
Staphylococcus aureus
Enterococci
E. coli
Pseudomonas aeruginosa
Streptococci
Enterobacter spp.
Staphylococcus aureus
Pseudomonas aeruginosa
Klebsiella pneumoniae
Serratia marcescens
Hepatitis B, C virus
Legionella pneumophila
*Probable underreporting: Salmonella spp., Campylobacter spp.,
norovirus, rotavirus, respiratory viral infections
Nosocomial outbreaks in Norway, 2005
Internet-based outbreak reporting system
• 47 outbreaks reported from hospitals with 622 cases
Norovirus
MRSA
Gastroenteritis
Listeria
Influenza
Other
Outbreaks
25
11
5
2
1
3
No. of cases
463
41
61
6
22
29
Grahek-Ogden et al. Varsler om mistenkte utbrudd av smittsomme sykdommer I Norge I 2005. MSIS rapport 2006;34:22 (in
Norwegian)
Gastmeier et al.
Source of outbreak
•
•
•
•
•
•
•
Patient – 26%
Medical equipment / device – 12%
Environment – 12%
Medical personnel – 11%
Contaminated drug – 4%
Contaminated food – 3%
Care equipment – 3%
• Unclear source – 37%
Gastmeier et al.
Mode of transmission
• Contact – 45%
• Invasive technique – 16%
• Inhalation – 15%
(droplet, airborne)
• Ingestion – 4%
• Unclear mode of transmission – 28%
Gastmeier et al.
Managing hospital outbreaks
•
•
•
•
•
•
•
•
•
Patient, health personnel screening, surveillance
Isolation, cohorting
Handwashing, hand disinfection
Sterilisation, disinfection
(Change) antibiotic therapy
Modification of care / equipment
Protective clothing
Restriction of work load
Vaccination
CDC guidelines
• Standard Precautions
• Contact / Droplet / Airborne Precautions
http://www.cdc.gov/ncidod/dhqp/gl_isolation_
standard.html
Detection of nosocomial outbreaks
• Alert from an effective surveillance system
• Alert from – the physician
– the nurse
– the hospital microbiologist
– the hospital epidemiologist
Nosocomial transmission?
• Similar cases at one department / among
similar patients
• Cases associated with invasive device
• Health personnel and patients with same
infection
• Nosocomial pathogen
Problems with detecting outbreaks
• No detection
– 2-3 patients with pneumonia in intensive care unit
• Detection
No investigation
– Nursing homes
• Detection
Investigation
No reporting
– If sanctions against reporting doctors, nurses
• False detection: pseudo-epidemics (artefacts)
– E.g. consequent laboratory contamination
– May lead to unnecessary antibiotic treatment
A method for early detection
• Reports from antibiotic susceptibility tests from each
medical ward (at least 85% culturing proportion)
• Baseline data: frequency of each pathogen isolated
from specimens over a 26-week observation period
Isolates
Weeks
2
1
1
2
3
3
2
4
4…
5…
5 2 1 1 3
22 23 24 25 26
Isolates
Weeks
1
1
1
2
1
3
2
4
2…
5…
3 3 4 4 5
22 23 24 25 26
• Threshold:
80% (4/5)
– Isolates ranked from the lowest to highest
– Divide the distribution into quintiles (fifths), and set the
cut-off between the 4th and 5th quintile
– The number of isolates represented by the 22nd week
item becomes the threshold value
Proteus mirabilis isolates
9
8
No. of isolates
7
6
5
4
Threshold (80%)
3
2
Baseline data
1
0
1
3
5
7
9
11 13 15 17 19 21 23 25
Weeks
Evaluation of the method
• Early warning mechanism
for potential outbreaks
• Sensitive if organisms are
routinely tested
• Either unusual and
common pathogens
• Epidemics involving
several locations might go
undetected
• Minimum effort and time
• Hospitals with limited
infection control personnel
• Establishing endemic
nosocomial infection rates
• Epidemics with prolonged
incubation might go
undetected
Investigation of nosocomial outbreaks
Steps of an outbreak investigation.. 
• Asset
– Diagnosis can usually be
made rapidly
– Direct access to medical
care, laboratory
– Patient’s records are
available
– Easy cohorting of the
cases
• Disadvantage
– Multidrug-resistent
pathogens
– Complex environment
– Intra – interhospital
transfer
– Temporary staff,
working in shifts
Case ascertainment
• The investigation is dependent on clearly
defined case definitions and case
ascertainment strategies
• Molecular diagnostics
– PFGE, PCR..
– Demonstrating clonality among epidemic
isolates
• Combinative approach
– Epidemiological study
– Genetic typing method
Steps of an outbreak investigation
•
•
•
•
•
•
•
•
Have an outbreak control plan
Confirm outbreak diagnosis
Define a case
Identify cases and obtain information
Descriptive data collection and analysis
Develop hypothesis
Analytical studies to test hypothesis
Communication (outbreak report)
Control
measures
www.mcht.nhs.uk/documents/policies/Infection_Control/A12%20-%20Hospital%20Outbreak%20Policy.pdf
A Norwegian example: Dent-O-Sept
• Antiseptic non-sterile single-use
swab for mouth hygiene
• Largest Pseudomonas outbreak
ever recorded in Norway
• 231 confirmed cases, 34 deaths
• Genotypically identical strains in
production plant, swabs and
patients
Alert to NIPH
• Late February 2002
• Notification from the infection control
personnel (not quantified by lab statistics)
• Impression of possible increase in the
number of pseudomonas infections in
clinical wards of Norwegian hospitals (ICU)
outbreak investigation
Outbreak investigation
• Objectives:
– Describe the outbreak
– Identify the cause
– Make recommendations for future prevention
• Outbreak Control Team:
– Members from NIPH and the hospitals
Initial investigation
• March 2002: identical outbreak strain is shown in
patients in 3 different hospitals
• No national surveillance system for P. aeruginosa in
Norway
• Inquiry for increased awareness in regional centers
for infection control
• Patient interviews/case notes with trawling
questionnaires in the affected hospitals (common
exposure?)
• Suspect: fluids and moist products
samples
Environmental investigation
• April 2002: laboratory identifies genotypically identical
strains of P. aeruginosa in swabs
control measures: information to the producer,
hospitals, authorities and the public, product recalled,
production ceased
• Hospitals were asked to report which batches of the
product they had in store
samples
• Inspection and sampling at the production plant
– Outbreak strain found in packing machine spraying
moisturizing liquid into the bags
– Violation of regulations (no documented quality
assurance system with microbiological testing..)
Case finding and descriptive study
• Norway: routine storage of all clinical
bacterial isolates from blood and
cerebrospinal fluid
• Isolates of P. aeruginosa from 1999-2002 to
reference labs for genotyping (PFGE)
• For patients with P.aeruginosa (outbreak
strain or other) questionnaire:
– Demographic and clinical data
Descriptive results
• 231 patients with outbreak stain from 27
health care institutions
–
–
–
–
Median age: 65 yrs, 61% men
87 pneumonia, 42 sepsis, 70 colonization
31% died (all had severe underlying disease)
31% had not or probably not used the swab
Dent-O-Sept outbreak – epidemic curve
50
40
Cases
30
20
10
10 11 12 1
2000
2
3
4
5
6
7
8
9 10 11 12 1
2
3
4
2001
Month and year of first positive test
5
6
2002
7
8
9 10 11 12
Analytical study 1.
• Case-control study
• Case definition: person with the outbreak
strain isolated from blood or CSF during
Oct 2001-Dec 2002
• Control definition: person with another
strain of P. aeruginosa isolated from blood
or CSF in the same period
• To identify risk factors for having the
outbreak strain
Results – CC study
Risk factor
Use of Dent-OSept swab
Been on
ventilator
OR
(95% CI)
5.3
(2.0-14)
6.4
(2.3-17)
P-value
0.001
<0.001
Patients with the outbreak strain were more likely to be
on ventilator / use the swab
Analytical study 2.
• Cohort study
• Including all patients in the CC study
• To identify risk factors for a fatal outcome
during hospital stay for patients with
invasive pseudomonas infection
Results – Cohort study
Risk factors for
dying
Use of Dent-O-Sept
RR
(95% CI)
2.2 (1.4-3.5)
Patients with fatal outcome were more likely to be
exposed to the swab
Confounding? (severely ill patients –> mouth swab
instead of tooth brush)
Lessons learned
• Direct transmission from swabs and
indirect transmission through health
personnel and contaminated environment
• Need to strengthen infection control
routines and standard precautions
– E.g. for patient with severe underlying disease
should only use sterile products
• Adherence to regulations in production of
medical equipment
Oakland Daily Evening Tribune, 06 Nov 1939
Media
• The outbreak may cause serious damage
to the hospital’s reputation
• Tool for education: ’message’
– Public: antibiotics = anti-cold drugs
– Professionals: every hospital need a plan for
antibiotic use
• Increased awareness: time to evaluate
routines, existing guidelines
(local/national/international level)
Summary
• Detection
– Effective surveillance system, vigilant hospital
personnel
• Investigation
– Skilled hospital infection control practicioner,
epidemiologist, microbiologist
• Prevention / Control
– Appropriate infection control practices
– Strategies to prevent and control antimicrobialresistent pathogens (antibiotic-plan)
The ultimate goal: patient safety