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Trichomonas vaginalis Nucleic Acid Amplification Testing at an Urban HIV Clinic

Muzny, Christina A. MD*; Burkholder, Greer A. MD, MSPH*; Fry, Karen R. MSN, CRNP*; Austin, Erika L. PhD, MPH; Schwebke, Jane R. MD*

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Sexually Transmitted Diseases: August 2016 - Volume 43 - Issue 8 - p 483-488
doi: 10.1097/OLQ.0000000000000479
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Trichomonas vaginalis, the most common nonviral sexually transmitted infection (STI),1 is associated with adverse pregnancy outcomes and increased risk for acquisition and transmission of human immunodeficiency virus (HIV) and other STIs.2–4 It is currently not reportable.5 Women are traditionally tested using a wet mount of vaginal fluid (point-of-care test using microscopy with 50–60% sensitivity),6 whereas men have not been tested due to lack of a convenient, sensitive test. Until the recent availability of the highly sensitive T. vaginalis nucleic acid amplification test (NAAT),7,8 the gold standard for T. vaginalis diagnosis was culture (sensitivity, 75–95%) which requires incubation and is categorized by the Clinical Laboratory Improvement Amendments as moderately complex.9,10 The T. vaginalis NAAT has been validated in asymptomatic and symptomatic women in multiple specimens (urine [95.2% sensitive], vaginal [100% sensitive], cervical [100% sensitive], and cervical ThinPrep Pap [100% sensitive]) and is run on the same platforms for Chlamydia trachomatis and Neisseria gonorrhoeae testing.7 Although the T. vaginalis NAAT can be used for male specimens (after internal laboratory validation), US Food and Drug Administration clearance for this indication has not been sought.

We previously determined the added value of NAAT for the detection of T. vaginalis in a large sample of women and men presenting to an STD Clinic.11 We found that the T. vaginalis NAAT detected approximately one third more infections in women than wet mount alone. Overall, T. vaginalis prevalence was 20.2% (27.0% in women, 9.8% in men). Additional data on the routine use of T. vaginalis NAAT in an HIV+ population is needed as current guidelines recommend T. vaginalis screening in all HIV+ women.5

The University of Alabama at Birmingham (UAB) 1917 HIV Clinic in Birmingham, AL, is a busy, urban HIV clinic that provides primary and subspecialty care to over 3000 HIV+ patients. It is staffed by 8 nurse practitioners (6 provide primary care services and 3 provide women's health services), 9 infectious diseases fellows, 20 infectious diseases faculty physicians (all provide primary care services), and 6 subspecialty faculty physicians (1 nephrology, 2 endocrinology, 1 psychiatry, 1 obstetrics-gynecology, and 1 neurology). Pelvic examinations and STI testing for women are typically performed by nurse practitioners (NPs) providing women's health services (wet mounts of vaginal fluid are mainly done for symptomatic women). The Hologic Aptima T. vaginalis NAAT recently became available at UAB in August 2014 at which time a letter was sent to all UAB providers by the main hospital laboratory (which internally validated the male test); NAAT results take approximately 3 days to return and are uploaded into an electronic medical record (EMR). At this clinic, the 1917 Clinic Cohort Observational Database Project ( is a prospective clinical study that collects detailed sociodemographic, psychosocial, and clinical data on HIV+ patients since 1992, as described in detail elsewhere.12,13 Since 2004, clinical and treatment data are captured at point-of-care by HIV providers on an EMR. The objectives of this study were to determine the uptake of T. vaginalis NAAT testing among providers at this clinic during the first year of test availability and to determine the prevalence and predictors of T. vaginalis infection among HIV+ women and men based on NAAT testing results.


This study was approved by the UAB institutional review board. Because we aimed to focus on the first year of Hologic Aptima T. vaginalis NAAT test availability, we initially determined the number of female and male HIV+ patients ages ≥16 years presenting to the UAB HIV clinic for care between August 2014 and August 2015. We then focused on female and male patients who received a T. vaginalis NAAT on a genitourinary specimen (urine, vaginal, cervical, urethral, or rectal) during this period. If a patient had >1 clinic visit with T. vaginalis NAAT testing performed during the study timeframe, data from the first date of testing were used. For each patient receiving a T. vaginalis NAAT, data on or closest to the date of the test were abstracted from the HIV Clinic Cohort database for sociodemographics (age, race, insurance status), tobacco use (current, prior), alcohol abuse (classified as “no risk,” “low risk,” and “at risk” by the Alcohol Use Disorders Test-Consumption questionnaire),14 substance abuse (current, prior) due to marijuana and/or cocaine (using the Alcohol, Smoking, and Substance Involvement Screening Test),15 sexual risk factor for HIV (available only for men and included men who have sex with women (MSW), men who have sex with men (MSM), and unknown), use of antiretroviral therapy, CD4 count, and HIV viral load (VL), T. vaginalis NAAT result, C. trachomatis and N. gonorrhoeae NAAT results, and T. vaginalis treatment data (i.e. evidence of a metronidazole prescription). For patients with a positive T. vaginalis NAAT, wet mount data were obtained for women by reviewing provider documentation notes in the EMR (wet mounts are read by a women's health NP).

Statistical analyses were performed using Stata 14.0 (StataCorp, College Station, Texas). Bivariate associations of demographic characteristics, risk behaviors, and HIV-related clinical results with a positive T. vaginalis NAAT among HIV+ patients were examined using χ2 tests. Logistic regression models were used to produce unadjusted odds ratios (ORs) and 95% confidence intervals (CIs) for those variables found to be significantly associated with a positive T. vaginalis NAAT in the preliminary analysis; variables were dichotomized as needed to simplify interpretation. Lastly, an adjusted model including all variables found to be significant at P < 0.05 in the unadjusted results was calculated. For all analyses, P < 0.05 was considered statistically significant.


Between August 2014 and August 2015, 3163 unique HIV+ patients (768 women and 2,395 men) were seen at the UAB HIV Clinic. Among these patients, a total of 861 (27.3%) of 3163 patients received a T. vaginalis NAAT on a urogenital specimen; 402 (52.3%) of 768 women and 459 (19.2%) of 2395 men. Figure 1 shows the overall proportion of women and men, whether or not they had T. vaginalis NAAT testing during the study period, and the proportion of each testing positive if they had the test performed. Of the 861 patients receiving a T. vaginalis NAAT, 70 (17.4%) of 402 women and 12 (2.6%) of 459 men tested positive (the prevalence among all tested was 82/861 [9.5%]). Among the 70 women with a positive T. vaginalis NAAT, 32 (45.7%) had a wet mount performed on the day that the NAAT was collected, of which 5 (15.6%) of 32 were read as positive for T. vaginalis.

Figure 1
Figure 1:
Proportion of HIV+ women and men presenting to the UAB 1917 HIV Clinic between August 2014 and August 2015 and receiving a T. vaginalis NAAT on a genitourinary specimen.

Table 1 demonstrates the characteristics of the 402 HIV+ women who received a T. vaginalis NAAT (113/402 [28.1%] had a urine NAAT whereas the remainder had either a vaginal or cervical NAAT). The majority of women were over age 40 (62.2%) years and of African-American race (79.8%). T. vaginalis NAAT positivity was significantly higher among those ages 25–40 years (25.5%; P = 0.006) and those without health insurance (25.8%; P = 0.007). Current cocaine use (36.4%) and being classified as “at risk” for alcohol abuse (25.0%) were significantly associated with a positive T. vaginalis NAAT (P = 0.009 and P = 0.002, respectively). In addition, a CD4 count of <200 cells/mm3 (P < 0.001) and HIV VL of >400 copies/ml (P < 0.001) were significantly associated with a positive T. vaginalis NAAT. Race, marijuana use, antiretroviral therapy, and C. trachomatis or N. gonorrhoeae infection were not significantly associated with a positive T. vaginalis NAAT (only 1/402 [0.2%] of women had a positive C. trachomatis NAAT (with the 1 C. trachomatis positive woman having a negative T. vaginalis NAAT); none of the women had a positive N. gonorrhoeae NAAT).

Characteristics and Prevalence of Trichomonas Vaginalis Infection Among Women Undergoing T. vaginalis Nucleic Acid Amplification Testing at the UAB 1917 HIV Clinic*

Table 2 reports the unadjusted and adjusted odds ratios for dichotomized predictors found to be significant among women. In the adjusted model, age ≤40 years was significantly associated with increased odds of a positive T. vaginalis NAAT (OR, 2.93; 95% CI, 1.23–6.96) as was current cocaine use (OR, 4.86; 95% CI, 1.57–15.06) and CD4 count <200 cells/mm3 (OR, 6.09; 95% CI, 1.68–22.11). Lack of health insurance, being “at risk” for alcohol abuse, and an HIV VL of >400 copies/mL were not significant in the adjusted model.

Correlates of Trichomonas vaginalis Infection Among Women Undergoing T. Vaginalis Nucleic Acid Amplification Testing at the UAB 1917 HIV Clinic

With regard to the men who had a T. vaginalis NAAT, 289 (63.0%) of 459 were MSM, 124 (27.0%) of 459 were MSW, and 46 (10.0%) of 459 were unknown. The majority (428/459, 93.2%) had a T. vaginalis NAAT on a urine specimen. With regard to the 12 men with a positive T. vaginalis NAAT (10 had a positive urine specimen and 2 had a positive rectal specimen [one of the men with a positive rectal specimen had a negative urine specimen for T. vaginalis on the same day whereas the other man did not have testing on a urine specimen]), the majority (9/12, 75%) were ages >40; 11 (91.7%) were African-American, and 1 (8.3%) was white. In addition, 9 (75%) were MSW, 1 (8.3%) was MSM, and 2 (16.7%) were unknown. With regard to laboratory parameters for men with a positive T. vaginalis NAAT, 2 (16.6%) 12 had a CD4 count <200 cells/mm3 and 10 (83.3%) of 12 had an HIV VL >400 copies/mL (neither of the men with a CD4 count <200 cells/mm3 had an HIV VL >400 copies/mL). None of the men with a positive T. vaginalis NAAT also had a positive C. trachomatis or N. gonorrhoeae NAAT. Because of the small sample size of men with a positive T. vaginalis NAAT (n = 12), we were unable to assess bivariate associations of demographic characteristics, risk behaviors, and HIV clinical results with T. vaginalis NAAT positivity.

For HIV+ women with a positive T. vaginalis NAAT, evidence of a metronidazole prescription was found for 65 (92.9%) of 70, prescribed either on the day of wet mount or after the T. vaginalis NAAT result returned (median days to treatment 5; interquartile range, 2–8 days). For HIV+ men with T. vaginalis, 10 (83.3%) of 12 were prescribed metronidazole after their T. vaginalis NAAT test result returned (median days to treatment, 4; interquartile range, 1–8 days).


This study is one of the first to present data on T. vaginalis NAAT utilization as part of routine care at an urban HIV clinic in the United States. Initial uptake of T. vaginalis NAAT testing during the first year was modest (27.3% overall) yet identified a high T. vaginalis prevalence among women tested (17.4%). Uptake among women (52.3%) was more than twice as likely than that in men (19.2%) (P < 0.001); however, the 19.2% uptake in men was fairly good given that there are no screening recommendations for T. vaginalis in men. Additional reasons for the modest uptake of T. vaginalis NAAT testing are likely multifactorial as providers have competing priorities (ie, need to order other recommended routine laboratory studies in addition to primary prevention measures) and time constraints while working in busy HIV clinics. There was also an HIV research study taking place at this clinic during the study timeframe that performed T. vaginalis wet mount testing on 87 HIV+ women; it is unknown if providers ordered T. vaginalis NAAT testing for these patients outside of the research protocol. Other potential reasons for the modest uptake could include limited provider awareness of the need for this testing, patients not being sexually active, patients receiving women's health care at other locations, and/or patients refusing testing. Future research should focus on identifying barriers to T. vaginalis NAAT testing in HIV clinics.

In this study, the prevalence of T. vaginalis by NAAT in women (17.4%) was greater than that in men (2.6%). Interestingly, T. vaginalis prevalence by NAAT among women was the same as that noted by culture in our 2013 study at this clinic,16 perhaps due to the high sensitivity (95%) of T. vaginalis culture at the UAB STI research laboratory.10 Use of wet mount (typically performed for symptomatic women at this clinic) for T. vaginalis point-of-care testing among women with a positive T. vaginalis NAAT was 45.7% (suggesting that over half of these women were asymptomatic) and had poor sensitivity.

The low T. vaginalis prevalence among HIV+ men is similar to that reported by van der Veer et al17 who found that T. vaginalis was rare among 1204 men attending an STD clinic (of which 56.3% were MSM) and limited to heterosexual networks; no T. vaginalis was found among MSM (who presumably would not be exposed to infected vaginal fluid). Similarly, another study found no T. vaginalis among 600 MSM.18 In our study, a relatively large proportion of men (63.0%) receiving a T. vaginalis NAAT were MSM which likely explains the low T. vaginalis NAAT prevalence. With regard to the 12 men with a positive T. vaginalis NAAT, only 1 was MSM whereas 9 were MSW (2 were unknown). Thus, these results do not support the routine screening of MSM for T. vaginalis. The low T. vaginalis prevalence among men might also be influenced by the high rate (36%–69%) of spontaneous resolution that is known to occur in men.19,20 It could also be a reflection of lower T. vaginalis screening rates among HIV+ men as national guidelines do not currently recommend routine screening.5 Nevertheless, the prevalence of T. vaginalis in a high risk heterosexual population can be substantial21,22 and serve as a source for reinfection of women; indeed, the prevalence of T. vaginalis by NAAT among MSW in our study was higher at 9 (7.3%) of 124. In a study of 1236 women tested for T. vaginalis by culture, 16.5% of infected women at baseline rescreened at 3 months were positive for T. vaginalis.23 Consideration should be given to routine screening of high risk heterosexual HIV+ men.

Of note, 2 men in this study had a positive rectal T. vaginalis NAAT. It is traditionally thought to be unlikely for T. vaginalis to colonize the rectum; however, several studies have similarly documented low rates of T. vaginalis in the rectum of men.24,25 Potential explanations are unknown but could include the deposition of T. vaginalis DNA (not necessarily live organisms) in the rectum by a bisexual male who is also having unprotected vaginal sex with an infected female.

In adjusted analysis, HIV+ women reporting current cocaine use (a possible marker for high risk sexual behavior) and those with a CD4 count <200 cells/mm3 were significantly more likely to test positive for T. vaginalis by NAAT. Prevalent T. vaginalis infection has been found to be associated with substance use, including crack cocaine.26,27 The latter finding is of interest in that T. vaginalis has not been considered an opportunistic infection in HIV+ women.16,28–30 It may be more of a marker of risk taking behavior(s), inconsistent STI screening, and/or lack of access to care. Additionally, HIV+ women aged >40 were significantly less likely to test positive for T. vaginalis by NAAT, similar to our prior study (using culture)16 and that of Magnus et al (using wet mount).30 This finding could be similar to the epidemiology of other curable STIs such as C. trachomatis and N. gonorrhoeae in which the prevalence is highest among young adults. In contrast, using molecular methods, others have found that increasing age is associated with prevalent T. vaginalis31,32 or that age is not associated.33

Numerous studies of women have found a racial disparity with African Americans more likely to have T. vaginalis.16,23,31,34 Although the majority of women in this study were African American (79.8%) and 19% had a positive T. vaginalis NAAT, we did not find that African American women were significantly more likely to have trichomoniasis compared with other racial groups. The effect of race may have been masked because, by definition, this was a high-risk group of women (11.8% of whites had a positive T. vaginalis NAAT as did 7.7% of women of other races) and the number of white women and women of other races was too small to facilitate comparisons.

Per recent CDC guidelines, routine STI screening (including screening for T. vaginalis) at entry to care and then at least annually is recommended for all HIV+ women (NAAT is encouraged).5 Retesting is recommended within 3 months after initial treatment. As mentioned, prior data in HIV+ men have been insufficient to recommend routine screening.5 In accordance with these guidelines, the results of this study suggest that measures are needed to standardize T. vaginalis screening, particularly for HIV+ women presenting for care at HIV clinics. Such standardized measures could include (1) comprehensive provider education on the need for routine T. vaginalis testing in at-risk patients, (2) increased use of point-of-care wet mount testing in women (if microscopy is available) by trained personnel or use of the OSOM® rapid antigen detection test, triggering immediate treatment if positive for T. vaginalis, (3) increased use of urine specimens or self-collected vaginal swabs for T. vaginalis NAAT among women without having to refer to a woman's health provider and/or performing a pelvic examination, (4) incorporation of the T. vaginalis NAAT into electronic provider order entry systems so that it is easily accessible, and (5) the addition of T. vaginalis NAAT test results on health maintenance lists (if in use by clinics) for HIV+ patients. Any specific measures should be incorporated into the flow of busy HIV clinics. Implementation of these measures may help to improve the diagnosis of T. vaginalis among HIV+ patients.

This study has limitations. First, it is not possible to know the true prevalence of T. vaginalis among HIV+ patients at this clinic because not every patient was tested during the study timeframe. Second, this study was retrospective which limited the amount of detailed sexual history, sexual behavior, and clinical diagnosis data obtained (ie, prior STI history, number of sexual partners, history of sex in exchange for money or drugs, condom use, current symptoms, current diagnosis of bacterial vaginosis, and so on), the ability to determine the selection process for patients that did have T. vaginalis NAAT testing performed, and whether uptake differed by type of provider (NP or MD) at the clinic. Third, metronidazole prescriptions could have reflected treatment for other conditions (such as bacterial vaginosis in women). Fourth, the results are from 1 urban HIV clinic in the southern US and may not be generalizable to other clinic populations. Fifth, although the sample size for HIV+ men receiving a T. vaginalis NAAT was larger than that for women, given the low prevalence of T. vaginalis among men it was not possible to evaluate associations between covariates and a positive T. vaginalis NAAT. Sixth, wet mount data for women with a positive T. vaginalis NAAT were abstracted from each patient's EMR which may have been incomplete. Finally, only the first T. vaginalis NAAT test per patient during the allotted 1-year timeframe was abstracted, thus we were not able to determine if patients had a new infection versus a persistent or recurrent infection. We were also not able to determine if women with T. vaginalis had a test of cure at 3 months, as recommended.5 These topics are of interest for future study.

Despite these limitations, the results of this study demonstrate that initial uptake of T. vaginalis NAAT testing during the first year of test availability was modest at this HIV clinic yet identified a high prevalence among women tested (17.4%). The prevalence among men tested was 2.6%. Among those patients tested, a high percentage of women and men with T. vaginalis were prescribed treatment. Emphasis on the need for routine testing of T. vaginalis (particularly among HIV+ women) is necessary to limit the adverse public health outcomes associated with this common infection. Additional studies to evaluate the cost-effectiveness of T. vaginalis screening by NAAT in HIV+ populations are also needed.


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