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Epidemiology oral session 5: Vaginal infections
O1-S05.05 Association between Trichomonas vaginalis and vaginal bacterial community composition among asymptomatic reproductive-age women in the USA
  1. R Brotman1,
  2. L L Jones1,
  3. J Sakamoto1,
  4. P Gajer1,
  5. K Ault2,
  6. L Peralta1,
  7. L Forney3,
  8. Z Abdo3,
  9. J Ravel1
  1. 1University of Maryland, School of Medicine, Baltimore, USA
  2. 2Emory University, School of Medicine, USA
  3. 3University of Idaho, USA


Background Vaginal bacterial communities are thought to prevent infection by sexually transmitted organisms. Prior work demonstrated that the vaginal microbiota of reproductive-age women in the US cluster into five groups of bacterial communities; four dominated by Lactobacillus spp. (L iners, L crispatus, L gasseri, L jensenii), and one lacking significant numbers of lactobacilli and characterised by higher proportions of strictly anaerobic organisms (termed group IV). We sought to compare the vaginal microbiota of T vaginalis-positive and T vaginalis-negative women using cultivation-independent methods. To our knowledge, this is the first analysis of the relationship between T vaginalis and vaginal bacterial communities characterised by molecular methodologies.

Methods Self-collected vaginal swabs were obtained cross-sectionally from 396 asymptomatic US women equally representing four ethnic/racial groups. Screening for the presence of T vaginalis was performed using PCR targeting the 18S rRNA and ß-tubulin genes. Vaginal bacterial composition was characterised by pyrosequencing of barcoded 16S rRNA genes. The relationship between vaginal microbiota and T vaginalis was evaluated by Fisher's exact testing and logistic regression.

Results Of the 11 T vaginalis-positive cases, 8 (72%) were classified to the low-Lactobacillus group IV, 2 (18%) and 1 (9%) with communities dominated by L iners and L crispatus, respectively (p value: 0.056). Group IV was associated with an eightfold increased odds of detecting T vaginalis compared to women with communities dominated by L crispatus (OR: 8.26, 95% CI: 1.07% to 372.65%, p value: 0.04). Other than the major bacteria dominating each cluster, none of the other observed taxa showed significant association with T vaginalis-positivity although this may reflect few observed cases rather than lack of a true association. Ten (91%) of the T vaginalis cases self-reported Black ethnicity and 1 (9%) reported Asian, (p value: 0.00002).

Conclusion Molecular analyses revealed that vaginal microbiota with low proportions of lactobacilli were significantly associated with presence of T vaginalis. Longitudinal studies are needed to identify the causal nature of the relationship between vaginal bacterial communities and STI risk.

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