Bacteria against bacteria: isolation, identification and characterization of bacteria with antimicrobial activities against Gardnerella vaginalis

Abstract

Gardnerella vaginalis is the etiological agent of bacterial vaginosis (BV), a chronic vaginal infection that affects women globally. Increasing antibiotic resistance and failing treatment options has resulted in chronic BV, demonstrating a need for novel alternative therapeutics. A total of 34 environmental bacterial isolates with antimicrobial properties against a G. vaginalis collection (n=17) were isolated and characterized for their antagonistic effects against G. vaginalis isolates and for their production of antimicrobial active agents. The G. vaginalis collection was shown to be diverse by genotyping and by their antibiotic susceptibility profiles. Anti-G. vaginalis (αGV) isolates were identified and phylogenetically clustered following full genome sequencing and their antiGV target range specificities were investigated. A subset of the αGV collection (n=20) were shown to produce and export active antimicrobial agents with molecular sizes of 4.6-35kD, which showed specific lethal effect on G. vaginalis isolates (target ranges of 5-100%). Cocktail formulations consisted of promising representatives from αGV clusters, with overlapping complimentary properties and specificity to G. vaginalis were identified for further study as the antimicrobial candidates for BV.