A Morphological Study of the in situ Tissue-Associated Autochthonous Microflora of the Human Vagina

Direct examination of scrapings from three locations in the vaginas of healthy volunteers, at different times of the menstrual cycle, revealed the presence in situ of tissue-associated autochthonous bacterial populations. Most of the bacteria in these scraped samples were intimately associated with the surfaces of epithelial cells, to which they were connected by elements of their exopolysaccharide glycocalyces. Washing of the epithelial sites, before sampling, removed vaginal secretions and their associated bacterial populations but did not remove the tissue-adherent bacterial microcolonies and individual cells. When epithelial cells were exposed to the high shear forces of vortex mixing, centrifugation and sonication, this firmly adherent bacterial population was almost entirely retained at the vaginal cell surface. The nature and strength of this intimate bacteria-tissue association may be important in the colonisation resistance afforded by autochthonous bacteria and in the pathogenesis of vaginal infections, and as such should be a major consideration in future ecological studies. KEY WORDS-Human vagina; Autochthonous flora; Tissue-association; Ecology