Recurrent bacteremia with Streptococcus dysgalactiae: a case-control study

Beta-hemolytic streptococci of groups C and G, designated as Streptococcus dysgalactiae (SD), can cause severe and recurring invasive infections. In this case-control study, we aimed to identify clinical and molecular risk factors for recurrence of SD bacteremia. Twenty-two cases of recurrent SD bacteremia were identified, and median time between episodes was 6 months. The most frequent clinical manifestation was skin and soft tissue infection. Cases and 92 controls, with single-episode SD bacteremia, showed similar demographics, had similar Charlson comorbidity scores, and had similar clinical presentations. Thirty-day fatality was 13% among controls, whereas none of 22 cases died. In 19 cases (86%), the same emm type was encountered in both episodes. SD isolates from recurrent episodes and from single episodes had a similar emm type distribution. Thus, we did not identify clinical risk factors for recurrences. The high proportion of identical emm types in recurrent episodes indicates a host-specific colonization.