Streptococcal Invasive Disease - Group A, 2002
One hundred forty-seven cases of invasive group A streptococcal (GAS) disease (3.0 per 100,000 population), including 24 deaths, were reported in 2002, compared to 200 cases and 15 deaths in 2001. (The case definition for GAS changed in mid-2002 to exclude some less invasive cases in which GAS was isolated from surgical specimens.) Ages of case-patients ranged from 4 months to 96 years (mean, 52 years). Fifty-six percent of case-patients were residents of the seven-county Twin Cities metropolitan area. Thirty (20%) case-patients had bacteremia without another focus of infection. There were 13 (9%) cases each of primary pneumonia and necrotizing fasciitis. Ten (7%) case patients had septic arthritis, and nine (6%) had streptococcal toxic shock syndrome (STSS).
The 24 deaths included four (17%) cases each of bacteremia without another focus of infection, pneumonia, and necrotizing fasciitis. Three (13%) cases had STSS, and two (8%) cases had both necrotizing fasciitis and STSS. The remaining fatal cases had bacteremia with another focus of infection, including four (17%) with cellulitis and one (4%) each with an abscess, puerperal sepsis, or septic arthritis. The deaths occurred in persons ranging in age from 20 to 92 years. For the 22 deaths in patients with known health histories, significant underlying medical conditions were reported for all but four of the cases.
Isolates were available for 134 (91%) cases, of which 131 were subtyped using PFGE; 46 different molecular subtypes were identified. Thirty subtypes were represented by one isolate each; other subtypes were represented by two to 39 isolates each. No epidemiologic links were noted among cases with identical subtypes, except for two cases from one nursing home and three cases from another nursing home. All residents and most staff were cultured at the facility with three cases; two residents and five staff members had positive throat cultures. All except one staff member's isolate had PFGE patterns that were indistinguishable from the outbreak strain. Each resident and staff person with a positive culture was treated with antibiotics, and no further cases have been identified at that facility.
The deaths were distributed among 11 different PFGE subtypes, with seven (29%) deaths attributed to the most common PFGE subtype. No other subtype accounted for more than two deaths.