Cutting edge: the vaginal microflora and bacterial vaginosis

Under physiological conditions, the vaginal primarily harbours lactobacilli which ideally confer in mutualism with the vaginal epithelium colonisation resistance to other micro-organisms, thereby preventing ascending or systemic infection. Albeit only a few Lactobacillus species constitute the vaginal microflora, huge species- and strain-specific differences occur however, and these differences account for a wide variability in the intrinsic capability of the Lactobacillus microflora to maintain the vaginal ecosystem. Hence, among a substantial proportion of women, the picture of lactobacilli-driven mutualism is actually less ideal than one may assume. As the vagina is incessantly subjected to cyclic changes as well as behavioural exposures that may challenge the perpetuation of the Lactobacillus microflora, the intrinsic stability of the resident microflora is paramount to women's health. Considering the close concordance between the rectal and vaginal lactobacilli, future research may benefit from the study of food, oral, and intestinal microbiology in relation to the vaginal Lactobacillus microbiota. Loss of the hydrogen peroxide producing lactobacilli accompanied by massive anaerobic overgrowth is observed with bacterial vaginosis. Molecular studies of the bacterial vaginosis microflora have recently revealed a tremendous species variability further documenting the complex polymicrobial nature of this condition. Emerging issues include the predominance of G. vaginalis, a normal microflora constituent possibly eliciting a host of virulence mechanisms at increasing concentrations through quorum sensing, the associated abundance of A. vaginae as a rather specific marker of therapy failure and disease persistence or recurrence, and the discovery of an adherent, metronidazole-resistant biofilm consisting of the latter two species.