Use of Continuous Culture to Model the Establishment of Bacterial Vaginosis
Busman, Benjamin M.
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Bacterial vaginosis (BV) is the most common vaginal tract infection among women of childbearing age seen in primary health care in the United States. BV is a polymicrobial syndrome characterized by an alteration in the composition of the vaginal microflora. This includes a decline in the concentration of Lactobacillus populations, which are generally dominant in the healthy vagina, and an overgrowth of Gardnerella vaginalis and anaerobes. Currently, the mechanisms responsible for the decline in the lactobacilli are not well understood. Previous studies in this laboratory isolated a strain of Enterococcus faecium 62-6 that produced a bacteriocin-like inhibitor antagonistic to the growth of vaginal lactobacilli. It is our hypothesis that the introduction of an exogenous bacteriocin-producing bacterium, such as E. faecium 62-6, into the vagina could lead to the decline in concentration of vaginal lactobacilli, and thus be one mechanism leading to the establishment of the BV associated micro flora. The aim of this study was to use continuous culture to model the establishment of BV by determining whether the introduction of strain 62-6 to an established population of vaginal lactobacilli would lead to a decline in the concentration of the lactobacilli, and to determine whether any decline would correlate to inhibitor production. Enterococcus faecium 62-6 was shown to lead to a decline in the concentration of two vaginal strains of Lactobacillus acidophilus. Notably, the concentration of a strain of Lactobacillus, 62-5, isolated from the same host as the inhibitor producer strain (62-6) was essentially unaffected in co-culture. While the decrease in concentration of the sensitive lactobacilli could not be attributed to inhibitor production, these results nonetheIess suggest that the introduction of exogenous enterococci into the vaginal tract may be clinically significant as a mechanism that could lead to the decline in concentration of vaginal lactobacilli, and thus pave the way for the establishment of the BV -associated microflora.