Hospital Acquired Group A Streptococcal Infections What have we learned?

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Hospital AcquiredGroup A Streptococcal
InfectionsWhat have we learned?

• Nov. 20, 2008
• Nick Daneman
• Division of Infectious Diseases
• Sunnybrook Health Sciences Centre

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Invasive Group A StreptococcusDramatic Illness
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Invasive Group A StreptococcusDramatic Illness
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Invasive Group A StreptococcusDramatic Illness
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Invasive Group A StreptococcusDramatic Illness
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Invasive Group A StreptococcusDramatic Illness
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Invasive Group A StreptococcusDramatic Outbreaks
75 CASES, 10 DEATHS
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Invasive Group A StreptococcusDramatic Hospital
Outbreaks
3 year outbreak of Group A Streptococcal surgical
site infections Mastro NEJM 1990
56 Cases of Group A Streptococcal infection in a
nursery Nelson J. Ped. 1976
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• 1 nosocomial case
• enhanced surveillance
• isolate storage
• 2 nosocomial cases within 6months
• typing of isolates
• if same strain
• epidemiologic investigation
• culture health care workers

CID 2002
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• expert opinion
• review of a handful of literature outbreaks

CID 2002
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Objectives

• describe hospital acquired cases of invasive
  group A streptococcal infections in Ontario
• describe hospital outbreaks of invasive group A
  streptococcal infections
• in Ontario prospective surveillance
• systematic review of the literature
• provide evidence-based recommendations

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Methods Prospective Surveillance

• Ontario Group A Strep Study Group
• population-based surveillance
• Ontario (population 11,000,000)
• 1992 - 2000
• all invasive isolates
• microbiology labs
• all Ontario hospitals
• largest outpatient microbiology lab

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Methods Definitions

• invasive
• group A streptococcus from a sterile site
• hospital acquired
• neither present nor incubating at admission
• outbreak
• gt 2 cases of culture confirmed, symptomatic GAS
  infection
• epidemiologically linked
• caused by same M, T type
• indistinguishable by PFGE

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Methods Literature Review

• MEDLINE database, 1966-2004
• search terms
• Streptococcus pyogenes OR group A
  streptococcus OR group A streptococcal
• nosocomial OR outbreak OR cross-transmission
• review of reference lists
• manuscripts reviewed by 2 investigators

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Objectives

• describe hospital acquired cases of invasive
  group A streptococcal infections in Ontario
• describe hospital outbreaks of invasive group A
  streptococcal infections
• in Ontario prospective surveillance
• systematic review of the literature
• evidence based recommendations

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CID 2005
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Ontario Prospective Surveillance 1992- 2000
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Hospital-acquired cases
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Differences cannot be explained by M-types
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Group A StrepSurgical Site Infections

• 96 cases
• out of 9,078,030 surgical admissions
• 1.1 cases / 100,000 surgical admissions
• entire range of surgical procedures
• digestive tract 28
• musculoskeletal 24
• cardiovascular 9
• nervous system 11
• skin and soft tissue 9
• urogyne 8

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Timing of Invasive Group A Streptococcal Surgical
Site Infections
median 5d
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Group A StrepPostpartum infections

• 86 cases
• out of 1,269,722 live births
• 0.7 cases / 10,000 live births
• 1/10 as common as neonatal group B strep
  infections
• but these were infections of mothers (only 2
  newborn cases, both non-invasive)

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Post-partum M28 association
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Post-partum M28 association

• M28 predominated in CDC postpartum surveillance1
• also predominates in perineal infection in
  children2
• express surface protein (R28) related to
  cell-surface molecules in Group B Strep which
  enhance binding to cervical epithelium

1. Chuang CID 2002 2. Mogielnicki Ped 2000 3.
Stalhammar MM 1990
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Group A StrepNon-surgical, non-obstetrical
infections

• 109 cases
• 40 of all cases
• (despite no mention in nosocomial group A strep
  guidelines)
• time of onset
• median 10.5 days
• range 2d to gt1 year
• ?community or nosocomial acquisition?

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Group A StrepNon-surgical, non-obstetrical
infections

• most common syndromes
• primary bacteremia 33
• non-necrotizing soft tissue infection 32
• lower respiratory tract infection 21
• necrotizing fasciitis 6
• 32 / 35 skin infections were associated with
  pre-existing skin breakdown
• IV lines (16), G-tubes /tracheostomy (6), chronic
  ulcers (5), trauma (2), burns (1), other lesions
  (2)

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Risk factors for mortality among
hospital-acquired cases
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Objectives

• describe hospital acquired cases of invasive
  group A streptococcal infections in Ontario
• describe hospital outbreaks of invasive group A
  streptococcal infections
• in Ontario prospective surveillance
• systematic review of the literature
• recommendations

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Complementary methods
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Number of Outbreaks
Literature
Surveillance
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Outbreak Magnitude
Literature Review Prospective Surveillance p
Median cases (range) 10 (2-56) 2 (2-10) lt0.001
Median duration (range) 30d (1-1095) 6d (1-30) lt0.001
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Outbreak Patient Composition
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Outbreak InitiationIndex Cases

• 3/4 of indexes cases nosocomial cases
• two other sources of outbreaks
• ill health care workers
• 5 literature outbreaks
• community-acquired cases
• 9 of 11 admitted to ICU
• 5 of 9 necrotizing fasciitis

DiPersio 1996, Holloway 1967, Kakis 2002,
Lannigan 1985, Nicolle 1986, Schwartz
1992 Burnett 1990, Decker 1985, Ejlertsen 2001,
Quinn 1965, Walter 1974
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Outbreak InitiationRapid Tempo

• median interval between first two cases
• literature outbreaks 2.0d
• surveillance outbreaks 4.5d
• interval between first two cases lt1 month in
  80 of 81 outbreaks

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Outbreak Propagation

• patient to patient 47
• colonized health care worker 27
• environmental 9
• mixed 6
• insufficient information 11

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Outbreak PropagationColonized Health Care
Workers
Colonized health care worker
Patient-to-Patient/Environmental
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Outbreak PropagationColonized Health Care
Workers

• site of health care worker colonization
• 31 pharyngeal only
• 10 anal
• 2 vaginal
• 5 skin

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Outbreak PropagationEnvironmental sources

• bidet
• hand shower
• vinyl sheet
• airflow mattress
• multidose vaccine vials (3)
• food borne outbreak (1)

Claesson 1985, Decker 1976, Gordon 1994, Reid
1983, Rutihauser 1999, Decker 1985
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Outbreak TerminationTreatment of Colonized HCWs

• data from 24 literature outbreaks
• first regimen usually successful
• pharyngeal carriage only 9/9 (100)
• nonpharyngeal carriage 11/15 (73)
• 4 failures
• 2 ongoing transmission
• 2 late relapses (4mos and 15mos)
• all ultimately successfully eradicated

Berkelman 1982, McIntyre 1968, Schaffner 1969,
Viglionese 1991
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Outbreak TerminationPatient to Patient
Transmission

• multifaceted control measures required
• 1st attempt usually unsuccessful (14/25)
• most effective control measures
• ward closure (86 success)
• mass treatment/prophylaxis (69 success)

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5 Recommendations
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1 Target all Nosocomial Cases
Hospitalized
CID 2002
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2 Isolation of Necrotizing Fasciitis

• 11 community acquired index cases
• majority due to necrotizing fasciitis admitted to
  intensive care unit
• ? isolate necrotizing fasciitis on
• admission (pending cultures)

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3 immediate investigations

• current guidelines for single case
• enhanced surveillance isolate storage
• short interval between first cases (2-4d)
• will not prevent second case
• majority of outbreaks only 2 cases
• therefore, preemptive investigations

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4 One month ceiling

• current guidelines for 2 cases in 6 months
• type isolates if same strain
• epidemiologic investigations
• culturing health care workers
• virtually no outbreaks with initial interval
  gt1month
• limit investigations to cases within 1 month

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5 Tailor Investigation by Ward
Surgery/Labour Delivery
Miscellaneous Wards

• health care worker carriers
• broad epi search for linked staff
• cultures
• throat, anal, vaginal, skin
• test of cure for non-pharyngeal carriers

• patient and environmental reservoirs
• multifaceted infection control strategies
• isolation/cohorting
• disinfection
• sterilization
• ward closure
• mass treatment

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Summary

• 12 of invasive group A streptococcal infections
  are hospital-acquired
• three groups with different characteristics and
  outcomes
• surgical (1/100,000 surgeries)
• postpartum (0.7/10,000 births)
• non-surgical/obstetrical (largest group)

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Summary

• 10 of hospital-acquired cases are associated
  with outbreaks
• 90 of hospital-acquired cases are sporadic
• when outbreaks do occur they are smaller and
  shorter than those in the literature

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Summary

• these complementary data sources lead to 5
  recommendations
• 1 include all hospital cases in guidelines
• 2 isolate necrotizing fasciitis
• 3 immediate investigations after 1 case
• 4 one month ceiling for linked cases
• 5 tailor investigations management to ward

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Acknowledgements

• Dr. Allison McGeer
• Dr. Donald Low
• Karen Green
• Ontario Group A Streptococcal Study Group

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