by Larik Sonfar

Created on: May 23, 2008

Millions of women worldwide are affected each year by bacterial vaginosis. Women who have bacterial vaginosis most commonly experience excess vaginal discharge due to certain growths of bacteria in the vagina. Other conditions include preterm labor, pelvic inflammation, and the human immunodeficiency virus. Some women with bacterial vaginosis have no symptoms whatsoever. Despite numerous studies on bacterial vaginosis, its specific cause is still poorly understood. The authors of this experiment understood that bacteria in microbial communities can be identified without the need for cultivation. Simply characterizing ribosomal DNA sequences could reveal the specific type of bacteria. With this in mind, the investigation began.

Being an investigation based on a search for the specific bacterial cause of bacterial vaginosis, the key causal question for this experiment was obvious: [What causes bacterial vaginosis?]

It was hypothesized that specific species of bacteria were the cause of bacterial vaginosis. Different species of bacteria were presented as alternate hypotheses for being the specific cause of bacterial vaginosis, mainly including species of bacteria in the Clostridiales order.

In order to test these hypotheses, a total of eighty-seven women were recruited from two groups known to have high rates of bacterial vaginosis. Seventy-three of these women were then chosen for studies. Bacteria species were first identified in samples of vaginal fluid using a combination of tests utilizing broad-range polymerase-chain-reaction amplification of 16S rDNA with clone analysis, bacterium specific PCR assays, and fluorescence in situ hybridization performed on the vaginal samples. Tests were performed both on a group of twenty-seven subjects with bacterial vaginosis and on a group of forty-six without bacterial vaginosis. These tests proved conclusive in ruling out certain species of bacteria as specific causes of bacterial vaginosis.

The group of women without bacterial vaginosis tested positive for a range of one to six vaginal bacterial species and averaged three point three vaginal bacterial samples in each vaginal sample, while the group of women with bacterial vaginosis revealed a much greater bacterial diversity. This group had a range of nine to seventeen vaginal bacterial species and averaged twelve point six vaginal bacterial species per sample. Thirty-five unique bacterial species were found in the group with bacterial vaginosis, including several species

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