Department of Public Health - Acute Communicable Disease Control

Streptococcal Infections, Group A (IGAS) and
Toxic Shock Syndrome (STSS)

Invasive Group A Streptococcal (IGAS) disease is caused by the group A beta-hemolytic Streptococcus pyogenes bacterium. Transmission is by direct or, rarely, indirect contact. Illness manifests as various overlapping clinical syndromes including bacteremia without focus, sepsis, cutaneous wound or deep soft-tissue infection, septic arthritis, and pneumonia. It is the most common cause of necrotizing fasciitis, commonly known as “flesh eating bacteria.” IGAS occurs in all age groups but more frequently among the very old. Infection can result in severe illness, including death.

Streptococcal toxic shock syndrome (STSS) is a rare but extremely severe illness characterized by rapid onset of hypotension (low blood pressure) and shock. Other symptoms can include renal (kidney) impairment, coagulopathy (abnormality in the blood's ability to clot), adult acute respiratory distress syndrome, rash and local tissue destruction. Death occurs in up to 70% of people who develop streptococcal toxic shock syndrome.

For surveillance purposes in LAC, IGAS is defined as isolation of S. pyogenes from a normally sterile body site (e.g., blood, cerebrospinal fluid, synovial fluid, or from tissue collected during surgical procedures). Isolation can include a non-sterile site if associated with STSS or necrotizing fasciitis (NF). IGAS cases are characterized as STSS if the diagnosis fulfills the CDC or Council of State and Territorial Epidemiologists (CSTE) case definitions for this syndrome; and as NF if the diagnosis was made by the treating physician.