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Unexpected High Rates of Persistent Trichomonas vaginalis Infection in a Retrospective Cohort of Treated Pregnant Women

Lazenby, Gweneth B., MD, MSCR; Thompson, Lauren, BS; Powell, Anna M., MD, MSCR; Soper, David E., MD

Sexually Transmitted Diseases: January 2019 - Volume 46 - Issue 1 - p 2–8
doi: 10.1097/OLQ.0000000000000902
Original Studies

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

Methods This is a retrospective cohort study of women diagnosed with genital Trichomonas vaginalis from 2008 to 2017. We calculated the rate of persistent Trichomonas by dividing the number of positive Trichomonas tests collected 21 days or longer posttreatment by the total number of women treated and retested. Bivariate analysis was performed to compare the rates of positive tests after single and multidose metronidazole. Multivariate logistic regression was used to evaluate factors associated with persistent infection.

Results Five hundred forty-two women with 565 pregnancies were diagnosed with Trichomonas infection. The majority of subjects were prescribed either single-dose (n = 352) or multidose metronidazole (n = 74). Posttreatment Trichomonas tests were collected 21 days or longer in 326 subjects and 44% (143) were positive. Rates of positive Trichomonas tests among women receiving single-dose and multidose regimens were similar (45% vs. 40%, P = 0.50). Women who had ≥1 pregnancy affected by Trichomonas infection were more likely to have a positive test posttreatment (adjusted odds ratio, 20.1; 95% confidence interval, 1.9–215.3). Obese women were less likely to have a positive test posttreatment (adjusted odds ratio, 0.3; 95% confidence interval, 0.1–0.9).

Conclusions Given high rates of positive Trichomonas tests and increased detection with nucleic acid amplification tests (NAATs), all pregnant women should be retested with NAATs approximately 3 weeks posttreatment. Further studies are needed to determine the most effective treatment of Trichomonas infection in pregnant women.

Forty-four percent of pregnant women treated for Trichomonas in pregnancy had persistent infection 21 days posttreatment. These rates were similar among women treated with single and multidose metronidazole.

From the Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC

Conflicts of Interest and Sources of Funding: None declared.

Correspondence: Gweneth B. Lazenby, MD, MSCR, 96 Suite 634, Jonathan Lucas St, Charleston, SC 29425. E-mail:

Received for publication February 9, 2018, and accepted July 23, 2018.

© Copyright 2019 American Sexually Transmitted Diseases Association