Prevalence and morbidity of urethral Trichomonas vaginalis in Japanese men with or without urethritis
- Kensaku Seike1,
- Shin-Ichi Maeda1,
- Yasuaki Kubota1,
- Masayoshi Tamaki1,
- Mitsuru Yasuda2,
- Takashi Deguchi2
- 1Department of Urology, Toyota Memorial Hospital, Toyota, Aichi, Japan
- 2Department of Urology, Graduate School of Medicine, Gifu University, Gifu City, Gifu, Japan
- Correspondence to Dr Kensaku Seike, Department of Urology, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu City, Gifu 501-1194, Japan;
- Received 11 July 2012
- Revised 21 October 2012
- Accepted 24 December 2012
- Published Online First 24 January 2013
Objectives Trichomonas vaginalis is one of the pathogens causing sexually transmitted infections. This microorganism is a common pathogen among women, but its significance as a cause of morbidity among men remains uncertain. We sought to determine the prevalence and morbidity of T. vaginalis infection in Japanese men with and without urethritis.
Methods We examined urine specimens from 215 men with urethritis and 98 men without urethritis for the presence of urethral T. vaginalis by PCR assay.
Results Only four patients—one with gonococcal urethritis, one with non-gonococcal chlamydial urethritis, one with non-gonococcal non-chlamydial urethritis and one without urethritis—were positive for T. vaginalis. The prevalence of T. vaginalis was 1.4% in men with urethritis and 1.0% in men without urethritis. A possible relation between the appearance of T. vaginalis and clinical symptoms was not confirmed.
Conclusions In the present study, the incidence of urethral T. vaginalis infection appears to be rare in Japanese men with or without urethritis, and T. vaginalis may be an uncommon pathogen in male urethritis in Japan.
The protozoan Trichomonas vaginalis has been recognised as a pathogen of sexually transmitted infections (STIs). T. vaginalis can cause vaginitis in women but it may also be a pathogen for symptomatic or asymptomatic nongonococcal urethritis in men.1 The importance of T. vaginalis infection as a cause of morbidity in men remains uncertain. According to studies reported from several countries, geographic differences have been observed in the prevalence of T. vaginalis in men with NGU.1 In Japan, there have been few recent studies of the prevalence of T. vaginalis infection in men, and the number of cases attributable to this pathogen remains undetermined. We examined urine specimens from 313 Japanese men with and without urethritis for the presence of urethral T. vaginalis to determine the prevalence and morbidity of T. vaginalis infection in men with and without urethritis.
Subjects and methods
This study was conducted in accordance with the Declaration of Helsinki and was approved by the ethical committee of Toyota Memorial Hospital. The men who visited the Department of Urology at Toyota Memorial Hospital with or without symptoms of urethritis between October 2002 and June 2006 were enrolled in this study. All provided their informed consent. A total of 313 men were included in this study. All men had a history of sexual intercourse with female partners, but sexual orientation was not confirmed. Data regarding sexual history were not obtained from most men.
A portion of the first-voided urine specimen obtained from all men was subjected to PCR-based assays (AMPLICOR STD-1 assay) to detect Neisseria gonorrhoeae and Chlamydia trachomatis. Other portions of the first-voided urine specimens were examined by a PCR-microtitre plate hybridisation assay for the presence of Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma parvum (biovar 1), and Ureaplasma urealyticum (biovar 2) as previously reported.2 Still other portions of the first-voided urine specimens were examined by PCR-based assay for the presence of T. vaginalis.
We designed a set of specific primers for T. vaginalis, Tv18S-F1 (5′-cattggtgccttttggta-3′, nucleotides 411 to 429) and Tv18S-R1 (5′-tcacagtgaacgtaaaaatac-3′, nucleotides 599 to 578) to amplify the short 18S region of T. vaginalis ribosomal DNA (GenBank Accession No. U17510). A PCR mixture was prepared containing 1×PCR buffer (50 mM Tris-HCl (pH 8.3), 10 mM KCl, 5.0 mM (NH4)2SO4 and 2.0 mM MgCl2); 0.5 µM of the primers; 0.2 mM (each) deoxyadenosine triphosphate (dATP), deoxycytidine triphosphate (dCTP), thymidine triphosphate (dTTP) and deoxyguanosine triphosphate (dGTP); 1.25 U of FastStart Taq DNA polymerase (Roche Molecular Biochemicals, Mannheim, Germany) and 5 µl of prepared DNA solution in a total volume of 50 µl. PCR was performed using the GeneAmp PCR System 9600 (Applied Biosystems, Foster City, California, USA) under the following conditions: an initial cycle at 95°C for 10 min, followed by 50 cycles, each consisting of denaturation at 94°C for 30 s, annealing at 46°C for 30 s and primer extension at 72°C for 30 s, with a final cycle at 72°C for 7 min. The PCR products were separated in 3% agarose gel, and a DNA fragment of 189 base pairs was identified by ethidium bromide staining.
To confirm the specificity of the PCR for T. vaginalis, the amplification was performed by using the DNA of Trichomonas strains such as T. tenax and Pentatrichomonas hominis.
To determine the sensitivity of the PCR, the 189-bp fragment of the 18S ribosomal DNA sequences, which was amplified from T. vaginalis with a pair of primers, Tv18S-F1 and Tv18S-R1, was inserted into pT7 Blue T-Vector (Novagen, Madison, Wisconsin, USA), and the recombinant plasmid was then purified. A series of 10-fold dilutions of the plasmid, ranging from 103 to 101 copies per reaction, were prepared and used as templates for the PCR.
Two hundred and fifteen of the 313 men had symptoms and signs compatible with acute urethritis, including discharge and the presence of five or more polymorphonuclear leukocytes per high-power (×1000) microscopic field in Gram-stained urethral smears. The other 98 men, who visited our institution for STI screening, had no signs or symptoms of urethritis. All subjects were Japanese. The mean age of the men with urethritis was 24 years (range: 16–67 years) and that of the men without urethritis was 27 years (range: 18–53 years).
The PCR developed in the study was specific for T. vaginalis because there was no cross-amplification with T. tenax and P. hominis. The sensitivity of the PCR was 10 copies of DNA per reaction.
The urethral microorganisms detected in men with and without urethritis are summarised in table 1. N. gonorrhoeae was detected in 98 (45.6%) men with urethritis. Only four men—one with gonococcal urethritis, one with non-gonococcal chlamydial urethritis, one with non-gonococcal non-chlamydial urethritis and one without urethritis—were positive for T. vaginalis. The prevalence of T. vaginalis was 1.4% in the men with urethritis and 1.0% in the men without urethritis.
The clinical courses of the three men with urethritis who were positive for T. vaginalis are shown in table 2. In all cases, clinical symptoms disappeared after treatment, but T. vaginalis was always positive through the treatment period. The man without urethritis who was positive for T. vaginalis did not make successive visits to the clinic.
Two studies from Africa in the late 1990s reported a high prevalence of T. vaginalis. In seven West African countries, Pépin et al3 reported that 13.8% of men with urethral discharge and 5.6% of control men were positive for T. vaginalis infection. Watson-Jones et al4 reported that 11% of Tanzanian men in a rural community were positive for T. vaginalis infection. In the USA, two studies in the early 2000s reported that 13%5 and 17.3%6 of men attending an STI clinic were positive for T. vaginalis. In Japan, the prevalence of T. vaginalis in the 1960s was reported to be 4% among criminals.7 In our previous study in the early 2000s, T. vaginalis was not detected in 100 Japanese men with and without urethritis.8 The prevalence of T. vaginalis might be underestimated in the present study because the detection rate differs according to the method in which samples are examined, such as urine specimens, urethral swabs and urethral discharges.9 The prevalence of T. vaginalis in men in Japan appears to be lower than that in other countries.
In the present study, major morbidities were not observed in any of the four men with or without urethritis who were positive for T. vaginalis. These findings suggested that T. vaginalis might be an uncommon pathogen causing male urethritis. T. vaginalis has been detected in asymptomatic men or control men in many studies from various countries. Schwebke and Hook6 reported the prevalence of asymptomatic men attending an STI clinic to be 14.5%. Additionally, Mitteregger et al10 reported that T. vaginalis was detected in 33.7% of tissues obtained from men without clinical symptoms of prostatitis who underwent transurethral resection of the prostate for benign prostatic hyperplasia. However, major morbidity from T. vaginalis in men has been revealed by many European studies.1 Clinical conditions associated with trichomoniasis include non-gonococcal urethritis, prostatitis, epididymitis, urethral stricture disease and infertility. The significance of T. vaginalis as a pathogenic microorganism in male genitourinary infection remains controversial.
Four of the 313 Japanese men attending our clinic were positive for Trichomonas vaginalis infection.
T. vaginalis was detected by PCR-based assay of the first-voided urine specimen.
Major morbidities were not observed in any of the four men positive for T. vaginalis.
Contributors KS contributed to the design, data collection, analysis and interpretation, and prepared the first draft of the paper. S-IM co-designed and contributed to data collection, analysis and interpretation. YK and MT contributed to data collection. MY advised on analysis and interpretation. TD advised on analysis, assisted with the drafting of the paper and provided editorial input on all sections of the paper.
Competing interests None.
Patient consent Obtained.
Ethics approval The ethical committee of Toyota Memorial Hospital.
Provenance and peer review Commissioned; externally peer reviewed.