DIAGNOSIS OF TRICHOMONAS-VAGINALIS INFECTION BY PCR USING VAGINAL SWAB SAMPLES

Trichomonas vaginalis infection is the most prevalent nonviral sexuall y transmitted disease (STD) in the world. A PCR test using vaginal swa b samples for the detection of T. vaginalis was developed to add T, va ginalis infection to the growing list of STDs that can be detected by DNA amplification techniques. A primer set, BTUB 9/2, was designed to target a well-conserved region in the beta-tubulin genes of T, vaginal is, All strains (15 of 15) of T. vaginalis tested were successfully de tected by PCR giving a single predicted product of 112 bp in gel elect rophoresis. No such targeted product was amplified with DNA from Trich omonas tenax, Trichomonas gallinae, Chlamydia trachomatis, Neisseria g onorrhoeae, Giardia lamblia, Chilomastix sulcatus, Dientamoeba fragili s, and Entamoeba histolytica. An optimal analytical sensitivity of one T. vaginalis organism per PCR was achieved. Culture, performed with t he Inpouch TV culture system, was examined daily with a light microsco pe to identify T. vaginalis, Twenty-three of 350 (6.6%) vaginal swab s amples from women attending an army medical clinic were culture positi ve for T. vaginalis, Of these culture positive specimens, PCR detected 22 of 23 (96%) with primer set BTUB 9/2, and wet preparation detected only 12 of 23 (52%). Seventeen specimens were BTUB 9/2-PCR positive a nd culture negative. Ten of these discordant specimens were determined to be as true positive by PCR using primer sets TVA 5-1/6 and/or AP65 A/B, which target different regions in the T. vaginalis genome, and s even were determined to be false positive. The sensitivity of BTUB 9/2 -PCR was 97% and the specificity was 98%, The sensitivities of culture and wet preparation were 70 and 36%, respectively. The diagnosis of T . vaginalis infection by PCR is a sensitive and specific method that c ould be incorporated into a joint strategy for the screening of multip le STDs by using molecular amplification methods.