has been shown to be a cause of urethritis in males (10
). It is known to be sexually transmitted and may be associated with preterm birth and HIV acquisition in women (3
). Cross-sectional studies have shown a significant association between Trichomonas
infection and preterm birth (3
). However, a recent prospective treatment trial examining the benefit of treating women with asymptomatic trichomoniasis with higher than usual doses of metronidazole yielded negative results (8
), and thus the association remains controversial. The relationship of HIV to trichomoniasis seems clearer. Laga et al. reported a significant association between incident trichomoniasis and HIV seroconversion among women enrolled in a prospective study in Zaire (11
). Buve et al. reported significantly higher rates of vaginal trichomoniasis among women residing in cities with high prevalences of HIV than among those residing in cities with low prevalences and suggested that trichomoniasis may be an important factor in determining rates of HIV infection (2
). Control of trichomoniasis could result in significant public health benefits; however, control efforts have been hampered by the lack of a sensitive and convenient diagnostic test for males.
Reported prevalence rates of urethral infection with T. vaginalis
in males have varied depending on the population studied and the diagnostic techniques used. In his series of sentinel studies using cultures of urine, urethra, coronal sulcus, and semen specimens, Krieger et al. found a prevalence of 11% among men attending an STD clinic. Among men with Trichomonas
as the sole urethral pathogen, half of them had urethritis (10
). In a similar study conducted at an STD clinic in Denver, Colo., investigators used a urine sediment culture, which produced a prevalence of 2.8% (6
). In an interesting study reported by Saxena and Jenkins (16
), the prevalence of Trichomonas
among inner-city males from 16 to 22 years of age in a job training program was an astounding 58%. This group also had high prevalences of other STDs. Trichomonas
was detected by a combination of methods, including urine sediment culture and direct fluorescent antibody testing. This study also found that only half of men with Trichomonas
infections were symptomatic (16
The use of PCR for diagnosis of Trichomonas
in males has been previously reported in only one study, conducted by Hobbs et al. (5
). Wet-mount microscopy and urethral culture, as well as PCR detection with urethral swabs, were used in Malawi to study both men who attended an STD clinic and men who went to a dermatology clinic. The prevalence of infection among symptomatic men was 21%, compared to 12% in asymptomatic males. The sensitivity and specificity of the PCR assay were 82 and 95%, respectively. The investigators speculated that the lower-than-expected sensitivity of the PCR assay may have been the result of the long-distance transport of the specimens.
The results of our study differ from those of Hobbs et al. We found that PCR for the detection of Trichomonas in males was significantly more sensitive than culture. The prevalence of infection detected by PCR was 17%, a rate which was anticipated considering the high rates among women attending the clinic. The yield was greatest from urine specimens, which were not examined in the Malawi study. Although inhibition is a potential problem with these techniques, the rate of inhibition in the present study was only 2%. As with other studies comparing DNA amplification techniques to culture, the specificity of PCR appears artificially low due to the lower sensitivity of the present gold standard; however, the inherent nature of the PCR technique suggests that the true specificity of the assay is much higher.
In summary, for men attending an STD clinic, PCR analysis of urine specimens was far more sensitive than culture for the detection of Trichomonas and prevalence rates were high. Screening for Trichomonas among men at risk for STDs should be considered part of any public health initiative to control trichomoniasis.