Resolution and co-occurrence patterns of Gardnerella leopoldii, Gardnerella swidsinskii, Gardnerella piotii and Gardnerella vaginalis within the vaginal microbiome

Abstract

BackgroundGardnerella vaginalis is a hallmark of vaginal dysbiosis, but is found in the microbiomes of women with and without vaginal symptoms. G. vaginalis encompasses diverse taxa differing in attributes that are potentially important for virulence, and there is evidence that clades or subgroups within the species are differentially associated with clinical outcomes. The G. vaginalis species description was recently emended, and three new species within the genus were defined (leopoldii, swidsinskii, piotii). 16S rRNA sequences for the four Gardnerella species are all >98.5% identical and no signature sequences differentiate them.\n\nResultsWe demonstrated that Gardnerella species can be resolved using partial chaperonin-60 (cpn60) sequences, with pairwise percent identities of 87.1-97.8% among the type strains. Pairwise co-occurrence patterns of Gardnerella spp. in the vaginal microbiomes of 413 reproductive aged Canadian women were investigated, and several significant co-occurrences of species were identified. Abundance of G. vaginalis, and swidsinskii was associated with vaginal symptoms of abnormal odour and discharge.\n\nConclusionscpn60 barcode sequencing can provide a rapid assessment of the relative abundance of Gardnerella spp. in microbiome samples, providing a powerful method of elucidating associations between these diverse organisms and clinical outcomes. Researchers should consider using cpn60 in place of 16S RNA for better resolution of these important organisms.