Unexpected high rates of persistent Trichomonas vaginalis infection in a retrospective cohort of treated pregnant women.

BACKGROUND: Our primary objective was to determine the rate of persistent Trichomonas infection among pregnant women post-treatment. The secondary objective was to determine if oral multi-dose metronidazole was associated with fewer cases of persistent Trichomonas compared to single dose treatment.

METHODS: This is a retrospective cohort study of women diagnosed with genital Trichomonas vaginalis from 2008-17. We calculated the rate of persistent Trichomonas by dividing the number of positive Trichomonas tests collected ≥ 21 days post-treatment by the total number of women treated and retested. Bivariate analysis was performed to compare the rates of positive tests following single and multi-dose metronidazole. Multi-variate logistic regression was used to evaluate factors associated with persistent infection.

RESULTS: 542 women with 565 pregnancies were diagnosed with Trichomonas infection. The majority of subjects were prescribed either single dose (n=352) or multi-dose metronidazole (n=74). Post-treatment Trichomonas tests were collected ≥ 21 days in 326 subjects and 44% (143) were positive. Rates of positive Trichomonas tests among women receiving single dose and multi-dose regimens were similar (45% vs 40%, P=.50). Women who had ≥ 1 pregnancy affected by Trichomonas infection were more likely to have a positive test post-treatment [aOR 20.1 (95% CI 1.9-215.3)]. Obese women were less likely to have a positive test post-treatment [aOR 0.3 (0.1-0.9)].

CONCLUSIONS: Given high rates of positive Trichomonas tests and increased detection with NAATs, all pregnant women should be retested with NAATs ~3 weeks post-treatment. Further studies are needed to determine the most effective treatment of Trichomonas infection in pregnant women.