Bacterial vaginosis: no longer a simple infection

A recent study finds that women with bacterial vaginosis (BV) have complex vaginal infections that may include up to 35 unique bacterial species, some of which have no known close relatives.

The study, which used a combination of broad-range polymerase-chain-reaction (PCR) amplification of 16S rDNA with clone analysis, bacterium-specific PCR assay of 16S rDNA, and fluorescence in situ hybridization (FISH) performed directly on vaginal fluid, involved 27 women with BV and 46 controls.

While women without the condition typically harbored one to six bacterial species, with lactobacillus species being the most common, women with the infection typically had nine to 17 bacterial species detected per sample, with newly recognized species present in 32% to 89% of clones per sample library. The authors of the study detected 35 unique bacterial species in the women with BV, including three in the Clostridiales order, that are highly specific for the condition and only distantly related to other known entities.

One of the shortcomings of the study is that it sheds light on only dominant microbial populations; microorganisms present at concentrations of 106 or fewer colony-forming units per gram of vaginal fluid, such as group B streptococcus, are unlikely to be detected with PCR techniques.

Fredricks DN, Fiedler TL, Marrazzo JM. Molecular identification of bacteria associated with bacterial vaginosis. N Engl J Med. 2005;353:1899-1911.

Hiller SL. The complexity of microbial diversity in bacterial vaginosis. N Engl J Med. 2005;353:1886-1887.