Antibiotic Resistance-Susceptibility Profiles of and spp. From the Human Vagina, and Genome Analysis of the Genetic Basis of Intrinsic and Acquired Resistances.

The spread of antibiotic resistance is a major public health concern worldwide. Commensal bacteria from the human genitourinary tract can act as reservoirs of resistance genes playing a role in their transfer to pathogens. In this study, the minimum inhibitory concentration of 16 antibiotics to 15 isolates from the human vagina, identified as , , and , was determined. Eight isolates were considered resistant to tetracycline, five to clindamycin and quinupristin-dalfopristin, and four to rifampicin. To investigate the presence of antimicrobial resistance genes, PCR analysis was performed in all isolates, and five were subjected to whole-genome sequencing analysis. PCR reactions identified (M) in all tetracycline-resistant isolates, while both (M) and (L) were found in tetracycline-resistant isolates. The (M) gene in VA02-2 was carried within an entire copy of the transposon Tn. In VA01-10AN and VA01-14AN, the (M) and (L) genes were found contiguous with one another and flanked by genes encoding DNA mobilization and plasmid replication proteins. Amplification and sequencing suggested the gene to be complete in all isolates resistant to clindamycin and quinupristin-dalfopristin, while the gene contain mutations rendering to a non-functional LsaA in susceptible isolates. These results were subsequently confirmed by genome analysis of clindamycin and quinupristin-dalfopristin resistant and susceptible strains. Although a clinical breakpoint to kanamycin for has yet to be established, VA08-2AN showed an MIC to this antibiotic of 128 μg mL. However, genes involved in kanamycin resistance were not identified. Under the assayed conditions, neither (L) nor (M) from either or was transferred by conjugation to recipient strains of , , or . Nonetheless, the (L) gene from VA01-10AN was amplified by PCR, and cloned and expressed in , to which it provided a resistance of 48-64 μg mL to tetracycline. Our results expand the knowledge of the antibiotic resistance-susceptibility profiles of vaginal bacteria and provide the genetic basis of their intrinsic and acquired resistance.