Colonization of the upper genital tract by vaginal bacterial species in nonpregnant women

Abstract

The objective of the study was to evaluate the upper genital tract (UGT) presence of vaginal bacterial species using sensitive molecular methods capable of detecting fastidious bacterial vaginosis (BV)-associated bacteria. Vaginal swabs were collected prior to hysterectomy. The excised uterus was sterilely opened and swabs collected from the endometrium and upper endocervix. DNA was tested in 11 quantitative polymerase chain reaction (PCR) assays for 12 bacterial species: Lactobacillus iners, L crispatus, L jensenii, Gardnerella vaginalis, Atopobium vaginae, Megasphaera spp, Prevotella spp, Leptotrichia/Sneathia, BVAB1, BVAB2, BVAB3, and a broad-range16S ribosomal ribonucleic acid gene assay. Endometrial fluid was tested with Luminex and an enzyme-linked immunosorbent assay for cytokines and defensins and tissue for gene expression of defensins and cathelicidin. We enrolled 58 women: mean aged 43±7 years, mostly white (n=46; 79%) and BV negative (n=43; 74%). By species-specific quantitative PCR, 55 (95%) had UGT colonization with at least 1 species (n=52) or were positive by 16S PCR (n=3). The most common species were L iners (45% UGT, 61% vagina), Prevotella spp (33% UGT, 76% vagina) and L crispatus (33% UGT, 56% vagina). Median quantities of bacteria in the UGT were lower than vaginal levels by 2-4 log10 ribosomal ribonucleic acid gene copies per swab. There were no differences in the endometrial inflammatory markers between women with no bacteria, Lactobacillus only, or any BV-associated species in the UGT. Our data suggest that the endometrial cavity is not sterile in most women undergoing hysterectomy and that the presence of low levels of bacteria in the uterus is not associated with significant inflammation.