Severe invasive streptococcal infection is defined as invasive group A streptococcal disease, in which Streptococcus pyogenes affects normally sterile body sites [1]. S. pyogenes are gram-positive cocci that grow in chains and exhibit β-hemolysis (complete hemolysis) on blood agar plates [1]. They belong to group A in the Lancefield classification system for β-hemolytic Streptococcus [1].
Disease overview
BacterialSevere invasive streptococcal infection
严重侵袭性链球菌感染
Evidence-backed informationEN 5/7 applicable sections · ZH 5/7 applicable sectionsUpdated Sep 3, 2026
Severe invasive streptococcal infection refers to invasive disease caused by group A Streptococcus (Streptococcus pyogenes), a gram-positive, β-hemolytic bacterium belonging to Lancefield group A [1]. This condition occurs when the bacteria infect normally sterile body sites, potentially leading to life-threatening presentations including necrotizing fasciitis and streptococcal toxic shock syndrome [1]. Surveillance data from CDC indicate highest disease rates among older adults, with documented outbreaks occurring in healthcare and long-term-care settings [1]. Prevention relies on limiting exposure, prompt diagnosis and treatment, appropriate infection-control precautions, and targeted prophylaxis in selected situations, as no vaccine is currently available [1].
Read the full clinical and epidemiological profile6
Invasive group A streptococcal disease can manifest as severe cellulitis with bloodstream infection, pneumonia, necrotizing fasciitis, and streptococcal toxic shock syndrome [1]. These presentations represent the severe end of the disease spectrum when bacteria invade sterile body sites [1].
CDC tracks invasive group A streptococcal disease, with documented occurrence in both community and institutional settings [1]. The burden is highest among older adults [1]. Outbreaks have been documented in healthcare settings and long-term-care facilities [1].
Group A Streptococcus most often spreads person-to-person through respiratory droplets or direct contact with secretions such as saliva, wound discharge, or nasal secretions from an infected person [1]. Healthcare-associated spread has been documented [1]. Although rare, foodborne transmission may occur [1]. Environmental transmission via surfaces and fomites may be possible but is likely a less common route [1]. There is no evidence that pets can transmit the bacteria to humans [1].
Prevention strategies include limiting exposure to infected individuals, ensuring prompt diagnosis and appropriate treatment, implementing appropriate infection-control precautions, and providing targeted prophylaxis in selected situations [1]. No vaccine is currently available for group A streptococcal infection [1].
- 1US Centers for Disease Control and Prevention. Clinical Considerations for Group A Streptococcus | Group A Strep | CDC [Internet]. cited 3 Sept 2026.Available from: https://www.cdc.gov/group-a-strep/hcp/clinical-guidance/index.html
- A40
- 1B50
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Data access
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Official sourcesAuthority, cadence, notes1
JP NIID Weekly
Japan
Japan weekly infectious disease surveillance via NIID/JIHS.