P4 A critical comparison of three diagnostic techniques used for the detection of trichomonas vaginalis (TV)

Background British Association of Sexual Health and HIV (BASHH) has recommended that nucleic acid amplification tests (NAAT) to become a gold standard method of TV detection in the 2014 guidelines. Aims To compare the efficacy of traditional wet mount microscopy (WMM), culture and TMA (Transcription Mediated Amplification) by Aptima assay for the detection of TV in our local population. The cost effectiveness of TMA and staffing requirements will also be assessed. Methods All female patients with vaginal discharge, male contact patients and males with persistent urethritis were included. Aptima high vaginal/cervical swabs routinely tested for chlamydia or gonorrhoea by TMA were used for Aptima TV testing, as were urines. All swabs and urine samples had WMM performed and cultured in modified diamonds media. Positivity rate, sensitivity, specificity, positive predictive value (PPV) and costs per test were calculated. The statistical significance was measured by McNemars test. Results 436 patients were included in the study, 64 male and 372 female. 11 were positive by at least one method, including one male. All TMA positive patients were also positive by urine except for 2. There is no statistical difference between WMM and culture (p = 0.25) but a highly significant difference between TMA and culture (p = 0.0124) and TMA and WMM (p = 0.0043). TMA is the most expensive test at >£5 per test. Conclusions TMA is the most sensitive test for TV. It has fast turnaround time and suitable for female urine samples. Its use is limited due to cost and suitability for other samples e.g. in male patients.