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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 site1 (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 excluding the middle ear and superficial wound aspirates [e.g. skin and soft tissue abscesses]). 


  • demonstration of S. pyogenes DNA by an appropriately validated nucleic acid test (NAT) from a normally sterile site1.

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. 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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