Diagnosis of symptomatic and asymptomatic Trichomonas vaginalis infection by applying one tube nested PCR to vaginal discharge.J Egypt Soc Parasitol. 1999; 29(3):1031-46.JE
One tube nested-PCR targeting a species-specific Tv-E650 repeat family of T. vaginalis genome, was applied to vaginal discharge specimen to diagnose symptomatic and asymptomatic trichomoniasis. The test was compared with axenic culture examination, wet mount preparation and Papanicolaou stained smears. Four-hundred and fifty cases symptomatic and symptomatic were collected over two years. Out of 290 symptomatic women with cervicovaginitis and 160 asymptomatic women, 35 were culture positive for trichomoniasis. All culture positive specimens were PCR-positive giving a single product at 290 bp by agarose gel electrophoresis and recording 100% sensitivity, similar to culture examination. Among the 35 culture positive specimens, 12 were positive by wet mount and 21 were positive by Pap smear giving a 34.2% and 60% sensitivity, respectively. The standard and boiling DNA extraction methods were equally reliable but the latter was more simple, rapid and cheap. No specimens negative by PCR for trichomoniasis were positive by culture, wet mount or Pap smear. Moreover, specimens from cases with cervicovaginitis of non-trichomonal origin were negative by PCR. All samples of extracted DNA of T. vaginalis from positive culture tubes, used as positive controls, were also PCR positive at the expected product in gel, while no PCR product was detected with the negative DNA control including Chylamidia trachomatis and human DNA. It was found that the one-tube nested-PCR targeting the Tv-E650 repeat family of T. vaginalis is a simple, rapid sensitive and specific accurate method for diagnosis of symptomatic and asymptomatic vaginal trichomoniasis when applied to vaginal discharge.