Comparison between the research GEN-PROBE® APTIMA formatted assay for rRNA (AMP-TV) and a real-time...
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Comparison between the research GEN-PROBE® APTIMA formatted assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of Trichomonas vaginalis. Andrew Hardick 1 , Justin Hadick 1 , Rebecca Miller 1 , Billie Jo Wood 1 , Thomas C. Quinn 1,2 , Charlotte A. Gaydos 1

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Comparison between the research GEN-PROBE® APTIMA formatted assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of Trichomonas vaginalis

Andrew Hardick1, Justin Hadick1,

Rebecca Miller1, Billie Jo Wood1,

Thomas C. Quinn1,2, Charlotte A. Gaydos1

1- Johns Hopkins University Division of Infectious Diseases Baltimore, MD

2- NIAID, NIH, Bethesda, MD

Abstr. No. 710

Code. WP-131


Introduction
Introduction assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

  • Trichomonas vaginalis (TV), the most prevalent non-viral STI in the world, is a major cause of urethritis, vaginitis, and cervicitis

  • Estimated that in the United States alone, 3 million women contract the infection every year, less is known about the prevalence in men

  • NAATs (nucleic acid amplified tests) are powerful new assays for the detection of TV


Objectives
Objectives assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

  • Compare two assays for the detection of Trichomonas vaginalis

    • Gen-Probe APTIMA formatted assay for rRNA (AMP-TV) research only

    • B-TUB FRET, a real-time PCR assay targeting the β-tubulin gene


Methods
Methods assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

  • 290 men and 325 women were screened in two STD clinics

  • Male urine and duplicate self- administered female vaginal swabs were collected

  • Samples tested by two methods

    • Processing and testing for AMP-TV was done following Gen-Probe’s instructions

    • Samples were extracted by Roche MagNAPure-LC-robot and tested by B-TUB FRET PCR (Hardick et al. JCM 2003)


Methods con t
Methods Con’t assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

  • Discordant samples

    • Retested by:

      • AMP-TV

      • B-TUB FRET

    • Wet Prep for motile TV QNS

    • Tested by an alternate PCR using primers TVK3 and TVK4

  • True positive samples

    • Defined as 2 positive results by 2 different tests


Initial results
Initial Results assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

B-TUB FRET

+

_

+

_

AMP-TV

Initial AMP-TV

Sensitivity 96.7% (59/61)

Specificity 97.3 % (535/550)

PPV 79.7 % (59/74)

NPV 99.6% (535/537)


Initial results by gender
Initial Results by Gender assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

Females

Males

B-TUB FRET

+

B-TUB FRET

+

AMP-TV

+

AMP-TV

+

Initial AMP-TV Females

Initial AMP-TV Males

Sensitivity 98.0 % (49/50)

Specificity 95.6 % (259/271)

PPV 80.3 % (49/61)

NPV 99.6% (259/260)

Sensitivity 90.1% (10/11)

Specificity 98.9 % (276/279)

PPV 76.9 % (10/13)

NPV 99.6% (276/277)


Results of discordant testing males
Results of Discordant Testing: Males assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

True positive: Defined as 2 positive results by 2 different tests


Results of discordant testing females
Results of Discordant Testing: Females assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of


Resolution of discordant results
Resolution of Discordant Results assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

  • Samples 10 and 11 were resolved as true negative because they both were wet preparation negative and had negative repeat results by AMP-TV and B-TUB assays

  • Sample 12, which was QNS for further testing, was resolved as a true negative, since the wet preparation for TV was negative


Discordant resolution results
Discordant Resolution Results assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

Truly Infected

+

_

+

_

AMP-TV

Sensitivity 98.6% (69/70)

Specificity 99.1% (536/541)

PPV 93.2 % (69/74)

NPV 99.8% (536/537)

Resolved AMP-TV


Resolved results by gender
Resolved Results by Gender assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

Females

Males

Truly Infected

+

Truly Infected

+

+

AMP-TV

+

AMP-TV

Resolved AMP-TV Females

Resolved AMP-TV Males

Sensitivity 98.2% (56/57)

Specificity 98.1 % (259/264)

PPV 91.8 % (56/61)

NPV 99.6% (259/260)

Sensitivity 100% (13/13)

Specificity 100% (277/277)

PPV 100% (13/13)

NPV 100% (277/277)


Conclusion
Conclusion assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

  • High overall T. vaginalis prevalence was found in our study population

    • Overall prevalence was 11.5%

    • Female prevalence was 17.8%

    • Male prevalence was 4.5%

  • Female vaginal swabs and male urine samples are non-invasive specimens which can be easily obtained and tested in amplified tests for T. vaginalis

  • Specificity for both assays was excellent


Conclusion1
Conclusion assay for rRNA (AMP-TV) and a real-time PCR, B-TUB FRET, for the detection of

  • Excellent initial sensitivity for Gen-Probe AMP-TV for T.vaginalis

    • 96.7% Overall

    • 98.0% Female

    • 90.1% Male

  • Excellent resolved sensitivity for AMP-TV

    • 98.6% Overall

    • 98.2% Female

    • 100% Male

  • In this study, the TMA-TV research assay was a valuable sensitive and specific assay for detection of T.vaginalis