Abstract: Objective To determine the organism's isolation rate in bacterial vaginosis (BV), to establish a molecular diagnostic method for BV. Methods Totally 173 vaginal-fluid samples(91 with BV and 82 normal) were screened by clinical Amsel criteria. Bacterial genome DNA was extracted from the vaginal secretion samples. Eleven major vaginal bacterial species were detected by using 16SrRNA gene PCR assays to confirm its association with BV, and the utility of PCR for the microbiological diagnosis of BV. Statistical analysis was used to establish the best bacterial combination for diagnosis of BV. Results Leptotrichia/Sneathia, Atopobium vaginae, Megasphaera species, Mobiluncus mulieris and Prevotella among the bacterial species were significantly associated with BV, the organism's isolation rate between two groups had significant difference(P<0.01). As a diagnostic criteria of BV, getting a sensitivity of 93.41% and a specificity of 78.05% by co-detecting the three species, Atopobium vaginae, Leptotrichia and Megasphaera. Conclusion BV is a polymicrobial disease. PCR detection of one or more fastidious bacterial species is an effective reliable molecular diagnostic method.

Key words: bacterial vaginosis, vaginal microbial flora, molecular diagnosis