Background Trichomoniasis caused by Trichomonas vaginalis affects both men and women, although the clinical presentation differs. Infected women are more likely to have symptoms compared to infected men. Approximately 75% to 100% of men are asymptomatic in comparison to approximately 50% to 75% of women who are identified as asymptomatic. In South Africa, data on the prevalence and detection of T. vaginalis is well-documented; however, data on the molecular characterization of T. vaginalis is limited. The study aimed to detect and characterise T. vaginalis isolates from HIV positive women attending an anti-retroviral clinic.

Methods Self-collected vaginal swabs from 380 HIV positive women were included in the study. Trichomonas vaginalis was detected using wet mount microscopy, culture and a commercial PCR kit. The genetic relatedness of 92 culture positive T. vaginalis isolates was determined. Five primers (TV1, TV2, TV3, TV5 and TV6) were used for the RAPD assay. The PCR-IGS-RFLP products were digested with five enzymes, namely: AluI , HinfI , RsaI , Sau3AI and Tsp509.

Results A total of 8% (30/380) of specimens were positive for T. vaginalis using microscopy, 24% (92/380) of specimens were positive using culture and 31% (118/380) of the specimens were positive using the commercial PCR kit. RAPD assay analysis showed a high level of genetic diversity between the T. vaginalis isolates. The dendrogrammes obtained from the RAPD data grouped the 92 T.vaginalis isolates into between nine to 24 clusters with 70% similarity used to define clusters, while the PCR-IGS RFLP assay results for the isolates were genetically indistinguishable.

Conclusion The PCR assay was the most sensitive diagnostic tool for the detection of T. vaginalis. A high prevalence of T. vaginalis, consisting of different strain types, was detected in the HIV positive women included in the study.