Comparative analysis of the vaginal microbiome of pregnant women with either Trichomonas vaginalis or Chlamydia trachomatis. Comparative analysis of the vaginal microbiome of pregnant women with either Trichomonas vaginalis or Chlamydia trachomatis

Background:Although the significance of the human vaginal microbiome for health and disease is increasingly acknowledged, differences in the composition of the vaginal microbiome upon infection with different sexually transmitted pathogens remain generally unexplored. Method:The vaginal bacterial composition of women with Trichomonas vaginalis (TV, N = 22) was compared to that of women with Chlamydia trachomatis (CT, N = 22), and controls (N =21) (women negative for both TV and CT). The vaginal bacterial composition was determined using high throughput sequencing with the Ion 16S metagenomics kit, of the variable regions 2, 4 and 8 of the bacterial 16S ribosomal RNA gene from the vaginal swab DNA extract of the women. QIIME and R package “Phyloseq” were used to assess the alpha and beta diversity and absolute abundance of the 16S rRNA gene per location in the three groups. Differences in taxa at various levels were determined using the independent T-test.Results:A total of 545 operational taxonomic units (OTUs) were identified in all the three groups of which 488 were the core OTUs. Bacterial α-diversity, by both Simpson’s and Shannon’s indices, was significantly higher, (p = 0.056) and (p = 0.001) respectively, among women with either TV or CT than among controls (median alpha diversity TV-infected > CT-infected > Controls). At the genus level, women infected with TV had significantly (p < 0.01) higher abundance of Parvimonas and Prevotella species compared to both controls and CT-infected women, whereas women infected with CT had significantly (p < 0.05) higher abundance of Anaerococcus, Collinsella, Corynebacterium and Dialister. Conclusion: The vaginal microbiomes of TV and CT-infected women were markedly different from each other and from women without TV and CT. Future studies should determine whether the altered microbiomes are merely markers of disease, or whether they actively contribute to the pathology of the two genital infections.