Group B Streptococcus or S. agalactiae (GBS) is a well documented cause of puerperal and neonatal (PNN) sepsis. Recently it has been observed as an important emerging pathogen in non-peripartum adults(NPA). Molecular epidemiologic methodology was applied to GBS isolates in both populations to determine if disparity or relatedness among strains existed. We evaluated 25 cases of serious NPA infections with GBS. Risk factors were studied. Isolates were compared with 18 blood perinatal/puerperal isolates by pulsed field gel electrophoresis (PFGE) to identify the strains by their DNA patterns.

The 25 adult patients included 8 with severe diabetic foot infections, 12 with sepsis, and 5 with other infections. Risk factors for infection in adults included diabetes and recent heart surgery. The 18 perinatal/puerperal infections included 5 newborns with sepsis, 13 mothers with chorioamnionitis or sepsis. All isolates were evaluated by PFGE. There was marked heterogeneity in band patterns among nonpuerperal infections. One strain was common among perinatal/puerperal isolates (8/18) and was also found in two NPA isolates. No other common strains were noted.

Although GBS classically causes perinatal infections, it has become an important pathogen in adults, causing diabetic foot infections, infected surgical wounds, and nosocomial sepsis. PFGE typing disclosed a common PNN strain which was uncommon among adult isolates, most of which were unrelated. Some characteristics(adhesion factors, local immunity) may have a role in PNN infections with GBS, but not in NPA infections. Further work to evaluate these factors is needed. It is hoped that a better understanding of the epidemiology of this organism will lead to better control mechanisms.