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Comparison of Cervical Samples to Vaginal Samples for the Detection of Trichomonas vaginalis Using a GEN-PROBE Research Assay for rRNA Andrew Hardick 1,

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Presentation on theme: "Comparison of Cervical Samples to Vaginal Samples for the Detection of Trichomonas vaginalis Using a GEN-PROBE Research Assay for rRNA Andrew Hardick 1,"— Presentation transcript:

1 Comparison of Cervical Samples to Vaginal Samples for the Detection of Trichomonas vaginalis Using a GEN-PROBE Research Assay for rRNA Andrew Hardick 1, Billie Jo Wood 1, Justin Hardick 1, Rebecca Miller 1, Mathilda Barnes 1, Thomas C. Quinn 1,2 Charlotte Gaydos 1 1. The Johns Hopkins University, Baltimore, MD. 2. NIAID, NIH, Bethesda, MD. INTRODUCTION Objective Trichomonas vaginalis (TV), a protozoan parasite, is the most prevalent non-viral STI in the world Estimated that in the U.S. alone, 3 million women contract the infection every year Is a major cause of vaginitis and non-gonococcal urethritis – In women, infection ranges from asymptomatic to profound, acute, inflammatory disease T. vaginalis usually infects the squamous epithelium of the genital tract Can be found in the urethra, cervix, fallopian tubes, and pelvic organs Vaginal swabs are traditionally used for diagnosis of T. vaginalis Chlamydia and gonorrhea can both be detected in cervical swab specimens METHODS DISCUSSION CONCLUSIONS Andrew Hardick The Johns Hopkins University Division of Infectious Diseases Department of Medicine 1159 Ross Bldg. 720 Rutland Ave. Baltimore, MD (410) Fax (410) RESULTS Determine if cervical swabs could serve as an adequate sample type for detection of Trichomonas vaginalis C-337 Board # 103 Specimens for this study were part of a larger study comparing a GEN-PROBE* APTIMA* format research assay (TMA* TV) to a research LightCycler* PCR assay for the detection of T. vaginalis 93 cervical and vaginal sample pairs were tested by the TMA TV assay Cutoff for a positive result was 40,000 RLU (Relative Light Units) A true positive was defined as 2 positive results by any 2 tests Discordant samples were tested by: – Research LightCycler PCR TV assay – PCR for TV using alternative gene target primers TVK 3 and 4 – Direct wet preparation for TV was performed at Clinics at time of sample collection Vaginal TMA TV Cervical TMA TV * GEN-PROBE, APTIMA and TMA are trademarks of Gen-Probe Incorporated; LIGHTCYCLER is a trademark of Roche Diagnostics GmbH T. vaginalis can be detected in both vaginal and cervical samples Kappa statistic indicates the agreement between vaginal and cervical samples was good No statistical difference in sensitivity and specificity estimates for vaginal and cervical specimens since 95% CI overlap The TMA TV assay could be useful for detection of T. vaginalis in clinical settings Prevalence of T. vaginalis was high, 19.4% (18/93) Overall agreement between cervical and vaginal samples to true T. vaginalis infected patients is high 94.1% (16/17) This suggests that either vaginal or cervical samples would be sufficient for the detection of T. vaginalis Overall Agreement: 92.5% Kappa Statistic: (strength of the agreement considered to be good) Resolution of discordant TMA TV results to true positives by alternative testing Of 5 TMA TV assay vaginal pos./ cervical neg. results: – 1 sample was: Wet preparation TV positive LightCycler PCR TV positive – 1 other sample was: PCR alternative primer set TVK 3/ 4 positive for TV Confirmed 2 out of 5 discordant samples as true positives Resolution of discordant TMA TV results to true positives by alternative testing Of 2 TMA TV assay vaginal neg./ cervical pos. results: – 1 sample was: LightCycler PCR TV positive PCR alternative primer set TVK 3/ 4 positive for TV Confirmed 1 out of 2 discordant samples as true positives Vag +, CX -TMA TV Vag CX Light- Cycler Alt. PCR TVK 3/ 4 Wet Prep. 1 True pos.+ _ + _ + 2 True pos.+ __ +NA 3+ ____ 4+ __ _ 5+ __ _ Vag-, CX+ 1 True pos. _ +++ _ 2 _ + _ NA _ RESULTS: Discordant Testing RESULTS: After Discordant Analysis Infected Patients Vaginal TMA TV Sensitivity 94.4% (17/18) (95% CI: 70.6%;99.7%) Specificity 96.0% (72/75) (95% CI: 87.9%; 98.9%) PPV 85.0% (17/20) NPV 98.6% (72/73) Cervical TMA TV Sensitivity 88.9% (16/18) (95% CI: 63.9%;98.0%) Specificity 98.7% (74/75) (95% CI: 91.7%; 99.9%) PPV 94.1% (16/17) NPV 97.3% (74/76) Infected Patients Cervical TMA TV


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