Group A Streptococcus

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Group A Streptococcus

• Streptococcus pyogenes

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Rising incidence of severe Invasive GAS
diseaseJAMA, 1993 269384

• Streptococcal toxic shock syndrome defined
• GAS infection
• Hypotension
• Multi-organ failure (2 or more of the following)
• Hepatic involvement
• Renal involvement
• Gastrointestinal involvement
• ARDS
• Hematologic involvement
• Generalized skin involvement

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IGAS in Ontario, CanadaNEJM, 1996 335547

• Population-based surveillance, 1992-3 in Ontario,
  Canada, N323 patients
• 1.5 per 100,000
• Highest risk
• Very young, very old
• 56 had underlying disease
• HIV
• Cancer
• Diabetes
• Alcohol abuse
• Chickenpox

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IGAS in Ontario, CanadaNEJM, 1996 335547

• Clinical presentations
• Soft tissue infection 48
• Bacteremia without focus 14
• Pneumonia 11
• Necrotizing fasciitis 6
• STSS 13
• Mortality 15
• Over 64 years 29
• STSS 81

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IGAS Case Definition

• Clinical description
• Invasive group A streptococcal infections may
  manifest as any of several clinical syndromes,
  including pneumonia, bacteremia in association
  with cutaneous infection (e.g., cellulitis,
  erysipelas, or infection of a surgical or
  nonsurgical wound), deep soft-tissue infection
  (e.g., myositis or necrotizing fasciitis),
  meningitis, peritonitis, osteomyelitis, septic
  arthritis, postpartum sepsis (i.e., puerperal
  fever), neonatal sepsis, and nonfocal bacteremia.

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IGAS Case Definition (2)

• Laboratory criteria for diagnosis
• Isolation of group A Streptococcus (Streptococcus
  pyogenes) by culture from a normally sterile site
  (e.g., blood or cerebrospinal fluid, or, less
  commonly, joint, pleural, or pericardial fluid)
• Case classification
• Confirmed a case that is laboratory confirmed
• Comment
• See also Streptococcal toxic shock syndrome

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STSS Case Definition

• Streptococcal toxic-shock syndrome (STSS) is a
  severe illness associated with invasive or
  noninvasive group A streptococcal (Streptococcus
  pyogenes) infection. STSS may occur with
  infection at any site but most often occurs in
  association with infection of a cutaneous lesion.
  Signs of toxicity and a rapidly progressive
  clinical course are characteristic, and the
  case-fatality rate may exceed 50.

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STSS Case Definition (2)

• Clinical case definition
• An illness with the following clinical
  manifestations occurring within the first 48
  hours of hospitalization or, for a nosocomial
  case, within the first 48 hours of illness
• Hypotension defined by a systolic blood pressure
  less than or equal to 90 mm Hg for adults or less
  than the fifth percentile by age for children
  aged less than 16 years.
• Multi-organ involvement characterized by two or
  more of the following (next slide)

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STSS Case Definition (3)

• Multi-organ involvement characterized by two or
  more of the following
• Renal impairment
• Coagulopathy
• Liver involvement
• Acute respiratory distress syndrome
• A generalized erythematous macular rash that may
  desquamate.
• Soft-tissue necrosis, including necrotizing
  fasciitis or myositis, or gangrene.
• Laboratory criteria for diagnosis
• Isolation of group A Streptococcus.

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STSS Case Definition (4)

• Case classification
• Probable a case that meets the clinical case
  definition in the absence of another identified
  etiology for the illness and with isolation of
  group A Streptococcus from a nonsterile site.
• Confirmed a case that meets the clinical case
  definition and with isolation of group A
  Streptococcus from a normally sterile site (e.g.,
  blood or cerebrospinal fluid or, less commonly,
  joint, pleural, or pericardial fluid).
• Comment
• See also Streptococcal Disease, Invasive, Group A
  and Toxic Shock Syndrome

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Public Health Action

• Case ascertainment
• Use the supplemental form to
• Document underlying disease
• Document type of infection
• If the case was hypotensive
• Determine if the case of invasive Group A
  Streptococcus meets the case definition for
  streptococcal toxic shock syndrome

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ProphylaxisCID, 2002 35950

• 2 studies identified 5 cases of household
  transmission in 2874 cases of IGAS, all adults.
• Do not routinely screen or prophylax.
• Health officials may choose to offer
  prophylaxis to household contacts most at risk
  for sporadic disease or death
• Health-case associated case
• Investigate one case (enhanced surveillance,
  typing)
• Screening epi-linked health care workers is
  strongly recommended if gt 2 cases occur in a 6
  month period

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IGAS - Outbreak ExampleJAMA, 1997 27738

• February, 1995 4 patients with IGAS 2 deaths
  from STSS in a 10-day period.
• Action
• PFGE
• Case definition IGAS matching the outbreak
  strain with onset Jan 1 to Mar 31, 1995 in a 17
  county area (subsequently revised to a 3-county
  area)
• Active surveillance
• Survey of school children and patients with
  pharyngitis

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IGAS - Outbreak Example (2)JAMA, 1997 27738

• Results
• Case-finding
• 7 cases that matched by PFGE outbreak clone
• 4 adults lived in community A served by school A
• 4 deaths
• Pharyngitis due to the outbreak clone
• Community A 7 (58) of 12 persons with GAS
• Community B 69 (26) of 260 persons with GAS

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IGAS - Outbreak Example (3)School SurveyJAMA,
1997 27738
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IGAS/STSS Summary

• STSS is more severe form of Streptococcus
  pyogenes infection
• Highest risk in elderly and individuals with
  chronic underlying disease
• Investigation
• Case ascertainment for IGAS and STSS
• Document
• Diagnosis
• Underlying disease