Presentation on theme: "RESULTS: After Discordant Analysis RESULTS: Discordant Testing"— Presentation transcript:
1 RESULTS: After Discordant Analysis RESULTS: Discordant Testing Board # 103Andrew HardickThe Johns Hopkins UniversityDivision of Infectious DiseasesDepartment of Medicine1159 Ross Bldg.720 Rutland Ave.Baltimore, MD 21205(410) Fax (410)Comparison of Cervical Samples to Vaginal Samples for the Detection of Trichomonas vaginalis Using a GEN-PROBE Research Assay for rRNA Andrew Hardick1, Billie Jo Wood1, Justin Hardick1, Rebecca Miller1, Mathilda Barnes1, Thomas C. Quinn1,2 Charlotte Gaydos1 1. The Johns Hopkins University, Baltimore, MD. 2. NIAID, NIH, Bethesda, MD.RESULTSVaginal TMA TVINTRODUCTION+-RESULTS: After Discordant Analysis152571+Trichomonas vaginalis (TV), a protozoan parasite, is the most prevalent non-viral STI in the worldEstimated that in the U.S. alone, 3 million women contract the infection every yearIs a major cause of vaginitis and non-gonococcal urethritisIn women, infection ranges from asymptomatic to profound, acute, inflammatory diseaseT. vaginalis usually infects the squamous epithelium of the genital tractCan be found in the urethra, cervix, fallopian tubes, and pelvic organsVaginal swabs are traditionally used for diagnosis of T. vaginalisChlamydia and gonorrhea can both be detected in cervical swab specimensCervical TMA TV-Infected PatientsInfected PatientsOverall Agreement: 92.5%Kappa Statistic: 0.764(strength of the agreement considered to be “good”)+-+-173172161274++Vaginal TMA TVCervical TMA TVResolution of discordant TMA TV results to true positives by alternative testingOf 5 TMA TV assay vaginal pos./ cervical neg. results:1 sample was:Wet preparation TV positiveLightCycler PCR TV positive1 other sample was:PCR alternative primer set TVK 3/ 4 positive for TVConfirmed 2 out of 5 discordant samples as true positives--Vaginal TMA TVSensitivity % (17/18)(95% CI: 70.6%;99.7%)Specificity % (72/75)(95% CI: 87.9%; 98.9%)PPV % (17/20)NPV % (72/73)Cervical TMA TVSensitivity % (16/18)(95% CI: 63.9%;98.0%)Specificity % (74/75)(95% CI: 91.7%; 99.9%)PPV % (16/17)NPV % (74/76)DISCUSSIONResolution of discordant TMA TV results to true positives by alternative testingOf 2 TMA TV assay vaginal neg./ cervical pos. results:1 sample was:LightCycler PCR TV positivePCR alternative primer set TVK 3/ 4 positive for TVConfirmed 1 out of 2 discordant samples as true positivesPrevalence 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. vaginalisObjectiveDetermine if cervical swabs could serve as an adequate sample type for detection of Trichomonas vaginalisMETHODSSpecimens 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. vaginalis93 cervical and vaginal sample pairs were tested by the TMA TV assayCutoff for a positive result was ≥40,000 RLU (Relative Light Units)A true positive was defined as 2 positive results by any 2 testsDiscordant samples were tested by:Research LightCycler PCR TV assayPCR for TV using alternative gene target primers TVK 3 and 4Direct wet preparation for TV was performed at Clinics at time of sample collectionRESULTS: Discordant TestingCONCLUSIONSVag +, CX -TMA TVVag CXLight-CyclerAlt. PCRTVK 3/ 4Wet Prep.1 True pos.+_2 True pos.NA345Vag-, CX+2T. vaginalis can be detected in both vaginal and cervical samplesKappa 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 overlapThe TMA TV assay could be useful for detection of T. vaginalis in clinical settingsGEN-PROBE, APTIMA and TMA are trademarks of Gen-Probe Incorporated; LIGHTCYCLER is a trademark of Roche Diagnostics GmbH
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