Invasive group A streptococcal infections in Sweden in 1994 and 1995: epidemiology and clinical spectrum.

A nationwide study of invasive group A streptococcal (GAS) infections in Sweden during 1994-1995 was carried out. All Swedish microbiological laboratories were asked to report isolates of GAS from normally sterile sites. During the study period they were also asked to send their isolates for T typing. Questionnaires were sent to the physicians in charge of each patient. The incidence, serotype, clinical presentation, symptoms and outcome were recorded. Clinical data were obtained for 468 of 556 patients with GAS bacteraemia. The lethality rate was 16%, but was much higher (37%) in the 113 patients who developed streptococcal toxic shock syndrome (STSS). Streptococci of serotype T1 dominated during the study period and were linked to the increase in invasive GAS infections. They also carried an increased risk of causing STSS. Invasive streptococcal disease with STSS most often has an unknown primary focus or is associated with soft tissue infections. Invasive streptococcal disease not associated with STSS most often has a skin infection as portal of entry or else an unknown focus.