Bacterial vaginosis (BV) is a recurrent condition that is associated with a range of negative outcomes, including the acquisition of human immunodeficiency virus and other sexually transmitted diseases, preterm births, and pelvic inflammatory disease. In contrast to the Lactobacillus-dominated normal vaginal microbiota, BV is characterized by a lack of lactobacilli and an abundance of anaerobic and gram-negative organisms, including Gardnerella vaginalis and Atopobium vaginae. To date, the laboratory diagnosis of BV has relied upon the fulfillment of criteria determined by microscopic observation of Gram-stained vaginal swabs. We describe a molecular-based method for the easy determination of the species profile within the vaginal microbiota based on the amplification of the chaperonin-60 genes of all bacteria present in the swab and hybridization of the amplicon to species-specific oligonucleotide-coupled fluorescent beads that are identified by flow cytometry with a Luminex instrument. We designed a nineplex Luminex array for characterization of the vaginal microbiota and applied it to the analysis of vaginal swabs from individuals from Africa and North America. Using the presence of A. vaginae or G. vaginalis, or both, as the defining criterion for BV, we found that the method was highly specific and sensitive for the diagnosis of BV using microscopy as a gold standard.Bacterial vaginosis (BV), which is defined by a reduction in the vaginal Lactobacillus populations and an increase in the number of microbial species present, including Gardnerella spp., Atopobium spp., and others, is increasingly recognized as an important risk factor for adverse reproductive health outcomes, such as miscarriage and premature birth, and sexually transmitted diseases, including human immunodeficiency virus infection (25). Despite intense investigation, the etiology and clinical course of BV have not been well defined, probably because the normal variation of the vaginal microbial communities between individuals and their dynamics over time are complex and poorly understood. Consequently, the accurate diagnosis of BV, as well as the elaboration of effective prevention and treatment strategies, remains a major challenge (26, 44).The current "gold standard" for the diagnosis of BV in the laboratory setting relies on microscopic profiling of microbial types in Gram-stained vaginal swab smears by using the criteria of Nugent et al. (29) or Ison and Hay (20). These scoring systems are based on the relative abundance of Lactobacillus morphotypes (large gram-positive rods) compared to the abundance of the bacterial morphotypes suggestive of BV (gramnegative or gram-variable coccobacilli and curved rods and gram-positive cocci). Although this method provides reliable information and is particularly well suited for use in resourcepoor settings, it requires well-trained, highly experienced individuals to interpret the results and is simplistic in its reflection of the variety of organisms present in the microbial communities present in he...