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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 t - PowerPoint PPT Presentation


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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
  • 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
  • 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
  • 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
  • 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

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

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

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

resolution of discordant results
Resolution of Discordant Results
  • 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

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

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
  • 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
  • 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
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