Group B streptococcus carriage and vulvovaginal symptoms: causal or casual? A case-control study in a GUM clinic...

The isolation of group B streptococcus (GBS) on routine swabs taken from genitourinary medicine (GUM) clinic attendees is a common finding. The relation of GBS to vulvovaginal symptoms is unclear, creating confusion about management. This case-control study tested the hypothesis that detection of GBS on routine clinical specimens is not causally related to vulvovaginal symptoms in female GUM clinic attendees.

Data were collected on all female GUM clinic attendees who had GBS isolated from anogenital swabs between July 1999 and July 2001. Controls were randomly selected from all new and rebooking female GUM clinic attendees. Controls were group matched for age with cases and were included only if a sexual health screen was performed and the results of this were available.

118 cases and 308 controls were identified during the study period. There was no significant difference between cases and controls in patient demographic or behavioural characteristics, the presence of genital co-infection, or vulvovaginal symptoms. There was no relation between symptoms and quantitative growth of GBS reported by the laboratory in either cervical or urethral swabs. Only nine cases had high vaginal swabs taken, in whom there was a significant association between a heavy growth of GBS and vulvovaginal symptoms (p=0.008).

The isolation of GBS from routinely collected genital swabs in female attendees of a GUM clinic is not causally related to vulvovaginal symptoms. We recommend that patients should receive this advice and should not be treated with antibiotic therapy for this indication.