Real-time PCR in diagnostics of Trichomonas vaginalis infection

Abstract number: P976

Sviben M., Vojnovic G., Kolcic I.

Objective:Trichomonas vaginalis is the most common parasitic cause of sexually transmitted infection in the world. Methods used for the laboratory diagnosis of T. vaginalis infection include microscopic examination of wet mount preparations, culture and more recently polymerase chain reactions (PCR). The objective of this study was to determine the prevalence of T. vaginalis infection in men tested at the Parasitology department of the Croatian National Institute of Public Heatlh between July and October 2007. A comparison of real-time PCR with culture and wet-mount microscopy in the diagnosis of trichomonosis was also performed.

Methods: Urine samples from 151 men were tested for T. vaginalis using culture and real-time PCR. One part of urine sediment was inoculated in Diamond's medium and examined for motile organisms after 24, 48 and 72 hours. From other part of sediment DNA was isolated using a spin column kit (High Pure PCR Template Preparation Kit; Roche Diagnostics GmbH). Real-time PCR was applied for detection of T. vaginalis DNA using a TaqMan Universal PCR Master Mix kit (Applied Biosystems). To rule out the presence of PCR inhibitors in the individual patient specimens, an internal control kit (TaqMan Exogenous Internal Positive Control Reagents; Applied Biosystems) was used. The amplification and detection were performed using 7500 Real Time PCR System machine (Applied Biosystems).

Results: Out of the 151 urine samples tested, 2 were positive by culture and 2 more (4 altogether) by PCR. The prevalence of T. vaginalis infection in male study population according to PCR was 3%. Real-time PCR also exhibited greater sensitivity than culture did (100 vs. 50%).

Conclusions: Despite all the efforts invested in development of better diagnostic tests for trichomonosis, PCR is not commonly used. The main reason is that T. vaginalis infection is not perceived as a significant public health problem. However, this perception should be changed based on recent studies suggesting a role of T. vaginalis in adverse pregnancy outcome and HIV transmission. A real-time PCR has immediate and important implications for diagnostic testing in the microbiology laboratory. The enhanced sensitivity, ease of performance and speed of this technology make it an appealing alternative to conventional methods which have been used for many years.