An adherent Gardnerella vaginalis biofilm persists on the vaginal epithelium after standard therapy with oral metronidazole

Abstract

The purpose of this study was to determine the efficacy of standard treatment with oral metronidazole in the eradication of the bacterial vaginosis biofilm. We conducted an interventional follow-up study in which 18 patients with bacterial vaginosis were treated with oral metronidazole during 1 week and subsequently had a single random follow-up assessment at 1-week intervals, up to 5 weeks, with 3 patients representing each point in time. Follow-up assessment included conventional scoring of the vaginal microflora and determination of bacterial biofilm characteristics on a vaginal biopsy through bacterial 16/23S recombinant DNA-based fluorescence in-situ hybridization. Although all patients recovered, we consistently observed the resurgence with treatment cessation of a dense and active bacterial biofilm on the vaginal mucosa, primarily consisting of Gardnerella vaginalis and Atopobium vaginae. A large reservoir of the core bacteria to bacterial vaginosis persists as a biofilm after metronidazole treatment.