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Sex Transm Dis. 2014 Feb;41(2):123-8. doi: 10.1097/OLQ.0000000000000075.

Bacterial vaginosis and the risk of trichomonas vaginalis acquisition among HIV-1-negative women.

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From the *Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington;Departments of †Global Health and ‡Biostatistics, University of Washington, Seattle, Washington; §Magee-Womens Research Institute, Pittsburgh, Pennsylvania; ∥Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; ¶Department of Obstetrics and Gynecology College of Health Science, University of Zimbabwe, Harare, Zimbabwe;**Center for Infectious Disease Research in Zambia, Lusaka, Zambia; ††HIV Prevention Research Unit, South Africa Medical Research Council, Durban, South Africa; ‡‡Division of Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina; §§Centre for the AIDS Program of Research in South Africa, Doris Duke Medical Research Institute, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Congella, South Africa; and ∥∥Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York.



The vaginal microbiota may play a role in mediating susceptibility to sexually transmitted infections, including Trichomonas vaginalis (TV).


Data were analyzed from HIV-1-seronegative women participating in HIV Prevention Trials Network Protocol 035. At quarterly visits for up to 30 months, participants completed structured interviews and specimens were collected for genital tract infection testing. T. vaginalis was detected by saline microscopy. Bacterial vaginosis (BV) was characterized by Gram stain using the Nugent score (BV = 7-10; intermediate = 4-6; normal = 0-3 [reference group]). Cox proportional hazards models stratified by study site were used to assess the association between Nugent score category at the prior quarterly visit and TV acquisition.


In this secondary analysis, 2920 participants from Malawi, South Africa, United States, Zambia, and Zimbabwe contributed 16,259 follow-up visits. Bacterial vaginosis was detected at 5680 (35%) visits, and TV was detected at 400 (2.5%) visits. Adjusting for age, marital status, hormonal contraceptive use, unprotected sex in the last week and TV at baseline, intermediate Nugent score, and BV at the prior visit were associated with an increased risk of TV (intermediate score: adjusted hazard ratio [aHR], 1.73; 95% confidence interval [CI], 1.21-2.19; BV: aHR, 2.40; 95% CI, 1.92-3.00). Sensitivity analyses excluding 211 participants with TV at baseline were similar to those from the full study population (intermediate score: aHR, 1.54; 95% CI, 1.10-2.14; BV: aHR, 2.23; 95% CI, 1.75-2.84).


Women with a Nugent score higher than 3 were at an increased risk for acquiring TV. If this relationship is causal, interventions that improve the vaginal microbiota could contribute to reductions in TV incidence.

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