In January 2001, an 87-year-old female resident of the same long-term care facility was transported to hospital with fever (index case-patient 2), and GAS was isolated from blood cultures drawn at admission. Several days later, GAS was isolated from the wound of another facility resident. Screening cultures performed on 195 residents and staff with a history of contact with one of these two infected persons indicated that seven residents and one staff member were colonized with GAS. PFGE showed that the strains from all resident carriers were identical to the wound and blood isolates, and to the isolate obtained from index case 1. The bacterial isolate obtained from the staff member was determined by PFGE to be unrelated to the outbreak strain. Colonized residents and staff were treated with cephalexin as had been done with the previous patient. Cultures obtained from treated persons 1 month after completion of therapy were again negative.
In May 2001, another resident of this nursing home was transported to hospital with GAS bacteremia (index case-patient 3). At this time, all 386 residents and 135 staff of the facility were screened for GAS carriage by culturing nasopharynx specimens. Eleven residents and three staff members were identified as carrying group A streptococcus. Thirteen of these (11 residents and two staff members) subsequently proved to be carrying strains identified by PFGE analysis to be identical to the strain obtained from index case-patient 2 (Figure 1) (prevalence of colonization or infection among residents was 2.8% vs. prevalence of colonization 1.5% among staff , p=0.38 by chi-square test).