(P459) Anorectal and vulvovaginal microbiota in Ecuadorian female sex workers with anorectal and urogenital STIs: evidence for cross-anatomical impact

Background

Vaginal microbiota changes associated with Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Mycoplasma genitalium (MG) and Trichomonas vaginalis (TV), can be linked to adverse reproductive health outcomes. Evidence suggests gastrointestinal tract (GIT) infections may affect extra-GIT microbiota. Full-length 16S rRNA gene sequencing may better identify microbiota to species level. We used long-read, full-length 16S rRNA gene sequencing to characterise vulvovaginal (VVS) and anorectal microbiota and their associations with urogenital and anorectal STIs in Ecuadorian female sex workers (FSWs).

Methods

VVS and anorectal DNA extracts were sub-selected from a wider study of FSWs from north-west Ecuador, previously tested for urogenital and anorectal CT, NG, MG and urogenital TV. Full-length 16S rRNA amplicon sequencing was performed using PacBio Hi-Fidelity (HiFi) circular consensus sequencing, reads mapped to a 16S rRNA NCBI database and analyses performed using R-based packages including phyloseq. Significance values were corrected for multiple testing.

Results

A total of 124 samples were sequenced, of which 83 were VVS and 43 anorectal, including 36 VVS-anorectal pairs from the same FSWs. Following normalisation, distinct species numbers were lower in VVS compared with anorectal samples (p < 0.0001), with the former exhibiting dominance by L. iners, G. vaginalis and F. vaginae, and the latter, greater evenness with high Bacteroidetes abundance. FSWs reported high usage of vaginal antimicrobial and cleaning products, and urogenital STIs had little effect on VVS microbiota diversity indices. Having an anorectal STI was independently associated with decreased anorectal richness (Chao β = -42, p = 0.018) with no impact on anorectal Shannon and Simpson diversity. In contrast, anorectal CT or NG infection was associated with greater VVS microbiota evenness (Simpson β = 0.31, p = 0.003; Shannon β = 0.67, p = 0.01) independent of urogenital STI status, with 5-fold increased Actinobacteria abundance (p = 0.02), dominated by G. vaginalis and F. vaginae, and 43% decreased Firmicutes abundance (p = 0.05), predominantly decreased L. iners.

Conclusions

Amongst vulnerable, highly sexually active Ecuadorian FSWs with high usage of vaginal products, anorectal STIs were independently associated with increased vulvovaginal microbial diversity with changes in vulvovaginal microbiota traditionally associated with poor reproductive health outcomes.