A preliminary study on the associations between Ureaplasma, Mycoplasma and the vaginal microbiome

Ureaplasma genus (including U. urealyticum and U. parvum) and M. hominis are common opportunistic pathogens in vaginal microenvironments, which would lead to bacterial vaginosis, infertility and adverse pregnancy outcomes. Ascertaining associations between these elements and the vaginal microbiome can help us identify pathogenic mechanisms, and target control measures for different colonization levels. 92 childbearing-age, non-pregnant women were included, with vaginal swabs collected. DNA was extracted and 16S rRNA genes were sequenced using the IlluminaHiseq 2500 platform. A quantitative PCR method quantified bacterial loads. The colonization rates for the Ureaplasma genus and M. hominis were 87.0 ​% (80/92) and 29.3 ​% (27/92), respectively. No M. genitalium was detected. There were no statistical differences for Simpson, Shannon and Chao1 indices between Ureaplasma negative and positive groups (P ​> ​0.05). Based on the quartile classification of relative abundance for Ureaplasma, the third quartile group had the highest relative abundance of Lactobacillus. The Simpson index for the M. hominis positive group was statistically lower than the negative group (P ​= ​0.038). The Lactobacillus abundance appeared to decrease when the M. hominis relative abundance was >0.03 ​%. From a microbiome perspective, Ureaplasma vaginal colonization, at low levels appeared to be harmless, whereas M. hominis colonization was associated with vaginal microbiome changes. Further studies are required to confirm the diagnostic and treatment thresholds for Ureaplasma and M. hominis infections, and to explore in-depth associations between these organisms and the vaginal microbiome.