Observational study of Streptococcus pyogenes isolated from vaginal swabs of adult women in a hospital and community laboratory

Abstract

Streptococcus pyogenes or group A streptococcus (GAS) is a common cause of vulvo-vaginitis in pre-pubertal females but is uncommonly isolated from the vaginal swabs of adult females. We aimed to describe the clinical and laboratory findings of adult females with GAS isolated from vaginal swabs in a community and hospital laboratory. Over a 19 week period the two laboratories identified females ≥ 15 years of age with GAS isolated from vaginal swabs. At least 2 weeks after reporting, the referring doctor or midwife was telephoned by the authors for clinical information or the clinical notes were reviewed. Laboratory data were also collected. One hundred adult females with GAS isolated from vaginal swabs were identified from approximately 4500-5000 community laboratory, and 20 from approximately 2000 hospital laboratory swabs. Community patients were more likely to have presented with vaginal symptoms such as discharge, while hospital patients were more likely to have ascending infection related to pregnancy/recent delivery. Of the community patients, 15% were asymptomatic compared with 5% of the hospital patients. Review of Gram stain and culture quantification was not found to be particularly useful for discriminating between clinical infection and asymptomatic colonisation. Isolation of GAS from the vaginal swabs of adult females is uncommon. In the community setting it may represent infection with vulvo-vaginitis or asymptomatic colonisation. In the hospital setting, its isolation is frequently associated with pregnancy-related infectious complications.