Nosocomial outbreaks

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Nosocomial outbreaks

• Agnes Hajdu
• EpiTrain III, 24.08.2006
• Jurmala, Latvia

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Content

• Nosocomial infections
• Health care setting
• Antimicrobial resistance
• Nosocomial outbreaks
• History
• Characteristics
• Outbreak database
• Detection, Investigation
• An example Dent-O-Sept
• Summary

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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)

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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

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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

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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

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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

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What can be worse than a nosocomial
infection?

• A Nosocomial Outbreak!!!
• An unusual increase in the number of
  nosocomial infections (time, place, person)

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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

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1847
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2006
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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

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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

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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

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Location
Gastmeier et al.

• 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

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Type of infections
Gastmeier et al.

• 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

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Most frequently reported pathogens
Gastmeier et al.

• Nosocomial infections
• Staphylococcus aureus
• Enterococci
• E. coli
• Pseudomonas aeruginosa
• Streptococci
• Enterobacter spp.

• Nosocomial outbreaks
• 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
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Nosocomial outbreaks in Norway, 2005

• Internet-based outbreak reporting system
• 47 outbreaks reported from hospitals with 622
  cases

Outbreaks No. of cases
Norovirus 25 463
MRSA 11 41
Gastroenteritis 5 61
Listeria 2 6
Influenza 1 22
Other 3 29
Grahek-Ogden et al. Varsler om mistenkte utbrudd
av smittsomme sykdommer I Norge I 2005. MSIS
rapport 20063422 (in Norwegian)
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Source of outbreak
Gastmeier et al.

• Patient 26
• Medical equipment / device 12
• Environment 12
• Medical personnel 11
• Contaminated drug 4
• Contaminated food 3
• Care equipment 3
• Unclear source 37

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Mode of transmission
Gastmeier et al.

• Contact 45
• Invasive technique 16
• Inhalation 15
• (droplet, airborne)
• Ingestion 4
• Unclear mode of transmission 28

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Managing hospital outbreaks
Gastmeier et al.

• 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

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CDC guidelines

• Standard Precautions
• Contact / Droplet / Airborne Precautions
• http//www.cdc.gov/ncidod/dhqp/gl_isolation_standa
  rd.html

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Detection of nosocomial outbreaks

• Alert from an effective surveillance system
• Alert from the physician
• the nurse
• the hospital microbiologist
• the hospital epidemiologist

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Nosocomial transmission?

• Similar cases at one department / among similar
  patients
• Cases associated with invasive device
• Health personnel and patients with same infection
• Nosocomial pathogen

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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

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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
• Threshold
• 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

80 (4/5)
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Proteus mirabilis isolates

Threshold (80)
Baseline data
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Evaluation of the method

• Early warning mechanism for potential outbreaks
• Either unusual and common pathogens
• Minimum effort and time
• Hospitals with limited infection control
  personnel
• Establishing endemic nosocomial infection rates

• Sensitive if organisms are routinely tested
• Epidemics involving several locations might go
  undetected
• Epidemics with prolonged incubation might go
  undetected

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Investigation of nosocomial outbreaks
Steps of an outbreak investigation.. ?

• Asset
• Diagnosis can usually be made rapidly
• Direct access to medical care, laboratory
• Patients records are available
• Easy cohorting of the cases

• Disadvantage
• Multidrug-resistent pathogens
• Complex environment
• Intra interhospital transfer
• Temporary staff, working in shifts

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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

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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
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www.mcht.nhs.uk/documents/policies/Infection_Contr
ol/A1220-20Hospital20Outbreak20Policy.pdf
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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

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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

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Outbreak investigation

• Objectives
• Describe the outbreak
• Identify the cause
• Make recommendations for future prevention
• Outbreak Control Team
• Members from NIPH and the hospitals

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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

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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..)

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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

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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

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Dent-O-Sept outbreak epidemic curve
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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

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Results CC study
Risk factor OR (95 CI) P-value
Use of Dent-O-Sept swab 5.3 (2.0-14) 0.001
Been on ventilator 6.4 (2.3-17) lt0.001
Patients with the outbreak strain were more
likely to be on ventilator / use the swab
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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

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Results Cohort study
Risk factors for dying RR (95 CI)
Use of Dent-O-Sept 2.2 (1.4-3.5)
Patients with fatal outcome were more likely to
be exposed to the swab Confounding? (severely ill
patients gt mouth swab instead of tooth brush)
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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

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Oakland Daily Evening Tribune, 06 Nov 1939
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Media

• The outbreak may cause serious damage to the
  hospitals 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)

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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
  antimicrobial-resistent pathogens
  (antibiotic-plan)

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The ultimate goal patient safety