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Streptococcal Disease, invasive Group A

Case definition

Confirmed case

Laboratory confirmation of infection with or without clinical evidence of invasive disease:

  • isolation of group A streptococcus (Streptococcus pyogenes) from a normally sterile site,1,2


  • demonstration of S. pyogenes DNA by an appropriately validated nucleic acid test (NAT) from a normally sterile site.1,2

Probable case

Clinical evidence of invasive disease in the absence of another identified aetiology and with non-confirmatory laboratory evidence of infection:

  • isolation of group A streptococcus from a non-sterile site, OR
  • positive group A streptococcus antigen detection 

Definition of clinical evidence

Clinical evidence of invasive disease may be manifested as one or more of several conditions:

  • streptococcal toxic shock syndrome
  • soft-tissue necrosis, including necrotizing fasciitis, myositis or gangrene
  • meningitis
  • fetal/infant death and clinical evidence of maternal illness compatible with iGAS

Definition of puerperal infection

Puerperal infection is defined as: postpartum iGAS occurring while the mother is still in hospital or within 7 days of hospital discharge or giving birth.


  1. Normally sterile sites include blood, CSF, pleural fluid, pericardial fluid, peritoneal fluid, deep tissue specimen taken during surgery (e.g. muscle collected during debridement for necrotizing fasciitis), bone or joint fluid.  Normally sterile sites exclude the middle ear and superficial wound aspirates (e.g. skin and soft tissue abscesses).
  2. When fetal demise or infant death occurs in association with a puerperal infection, isolation of group A streptococcus from the placenta, amniotic fluid and/or endometrium is also considered confirmatory for both the mother and the fetus/infant.
SOURCE: Streptococcal Disease, invasive Group A ( )
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