Serious Group B streptococcal infections: Clinical and molecular epidemiology

Group B streptococcus (GBS) infection in the neonate and penpartum female is well-known; GBS infection in non-pregnant adults is increasingly recognized. During 8 months of surveillance at a university county hospital, 30 serious GBS infections were detected (0.42 per 1000 pt days). 2 infections were in neonates; 5 were in penpartum females. The other 23 infections (77%) occurred in non-pregnant adults (mean age, 51 yrs). Types of infections included cellulitis (10; 9/10 in diabetics), bone/joint (5), urinary tract (3), intra-abdominal (2), endocarditis (1), catheter-related (1), and pneumonia (1). 11 of 23 (48%) of these infections (primarily cellulitis and osteomyelitis) were polymicrobial. MIC testing documented % susceptible to the following antibiotics: pen (100%), amp (100%), amp/SB(100%), trovafloxacin(100%), erythromycin (90%), tetracycline (10%). Pulsed-field gel electrophoresis (PFGE) typing documented 17 distinct PFGE types among 24 isolates typed. Two community-acquired penpartum infections were caused by PFGE type B. Among communityacquired GBS infections in non-pregnant adults, 4 infections were caused by PFGE type L; 3 by PFGE type A; 2 by PFGE type Q. The other 13 infections were caused by distinct PFGE types. PFGE typing results were correlated with serotyping. Non-pregnant adults are at risk for serious GBS infections which are often polymicrobial. GBS infection in peripartum and non-pregnant adults may be caused by both clonal and distinct strains.