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Hospital Acquired Group A Streptococcal Infections What have we learned?

Hospital Acquired Group A Streptococcal Infections What have we learned?. Nov. 20, 2008 Nick Daneman Division of Infectious Diseases Sunnybrook Health Sciences Centre. Invasive Group A Streptococcus: Dramatic Illness. Invasive Group A Streptococcus: Dramatic Illness.

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Hospital Acquired Group A Streptococcal Infections What have we learned?

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  1. Hospital AcquiredGroup A Streptococcal InfectionsWhat have we learned? Nov. 20, 2008 Nick Daneman Division of Infectious Diseases Sunnybrook Health Sciences Centre

  2. Invasive Group A Streptococcus:Dramatic Illness

  3. Invasive Group A Streptococcus:Dramatic Illness

  4. Invasive Group A Streptococcus:Dramatic Illness

  5. Invasive Group A Streptococcus:Dramatic Illness

  6. Invasive Group A Streptococcus:Dramatic Illness

  7. Invasive Group A Streptococcus:Dramatic Outbreaks 75 CASES, 10 DEATHS

  8. Invasive Group A Streptococcus:Dramatic Hospital Outbreaks 56 Cases of Group A Streptococcal infection in a nursery Nelson J. Ped. 1976 3 year outbreak of Group A Streptococcal surgical site infections Mastro NEJM 1990

  9. 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

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

  11. 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

  12. 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

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

  14. 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

  15. 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

  16. CID 2005

  17. Ontario Prospective Surveillance 1992- 2000

  18. Hospital-acquired cases

  19. Differences cannot be explained by M-types

  20. 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% • …

  21. Timing of Invasive Group A Streptococcal Surgical Site Infections median = 5d

  22. 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)

  23. Post-partum M28 association

  24. 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

  25. 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 >1 year • ?community or nosocomial acquisition?

  26. 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)

  27. Risk factors for mortality among hospital-acquired cases

  28. 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

  29. Literature Review Prospective Surveillance Publication bias Hawthorne effects Complementary methods

  30. 66 publications 2,351 invasive cases 60 available 291 nosocomial 29 outbreak-linked (20 outbreaks) 61 outbreaks Number of Outbreaks Literature Surveillance

  31. Outbreak Magnitude

  32. Outbreak Patient Composition

  33. Outbreak Initiation:Index 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

  34. Outbreak Initiation:Rapid Tempo • median interval between first two cases • literature outbreaks: 2.0d • surveillance outbreaks: 4.5d • interval between first two cases <1 month in 80 of 81 outbreaks

  35. Outbreak Propagation • patient to patient 47% • colonized health care worker 27% • environmental 9% • mixed 6% • insufficient information 11%

  36. Outbreak Propagation:Colonized Health Care Workers Colonized health care worker Patient-to-Patient/Environmental

  37. Outbreak Propagation:Colonized Health Care Workers • site of health care worker colonization • 31 pharyngeal only • 10 anal • 2 vaginal • 5 skin

  38. Outbreak Propagation:Environmental 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

  39. Outbreak Termination:Treatment 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

  40. Outbreak Termination:Patient 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)

  41. 5 Recommendations

  42. #1: Target all Nosocomial Cases Hospitalized CID 2002

  43. #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)

  44. #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

  45. #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 >1month • limit investigations to cases within 1 month

  46. 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 #5: Tailor Investigation by Ward Surgery/Labour & Delivery Miscellaneous Wards

  47. 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)

  48. 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

  49. 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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