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Volume 21, Number 1—January 2015

Use of Treponema pallidum PCR in Testing of Ulcers for Diagnosis of Primary Syphilis1

Angèle Gayet-AgeronComments to Author , Patrice Sednaoui, Stephan Lautenschlager, Tristan Ferry, Laurence Toutous-Trellu, Matthias Cavassini, Fatima Yassir, Begoña Martinez de Tejada, Stéphane Emonet, Christophe Combescure, Jacques Schrenzel, and Thomas Perneger
Author affiliations: University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland (A. Gayet-Ageron, L. Toutous-Trellu, B. Martinez de Tejada, S. Emonet, C. Combescure, J. Schrenzel, T. Perneger); Institut Alfred Fournier, Paris, France (P. Sednaoui); Triemlispital, Zurich, Switzerland (S. Lautenschlager); Hospices civils de Lyon, Lyon, France (T. Ferry, F. Yassir); Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (M. Cavassini)

Main Article

Table 1

Summary of the various indices of performance of Tp-PCR compared with DFM, serologic testing, or an enhanced definition for diagnosis of primary syphilis*

Reference testing Sensitivity (95% CI) Specificity (95% CI) Likelihood ratio (95% CI)
κ coefficient (95% CI) Post-test probability (95% CI)
Positive Negative If Tp-PCR is positive (PPV) If Tp-PCR is negative (1 − NPV)
DFM, n = 170 93.8% (79.2%–99.2%) 90.6% (84.4%–94.9%) 9.95 (5.89–16.82) 0.07 (0.02–0.26) 0.74 (0.62–0.87) 69.8% (53.9%–82.8%) 1.6% (0.2%–5.6%)
Serologic, n = 239 78.5% (68.4%–86.5%) 93.4% (88.2%–96.8%) 11.84 (6.44–21.77) 0.23 (0.16–0.35) 0.73 (0.64–0.82) 87.3% (78.0%–93.8%) 11.9% (7.3%–17.9%)
Enhanced definition, n = 170 87.5% (74.8%–95.3%) 99.2% (95.5%–100.0%) 106.75 (15.11–753.95) 0.13 (0.06–0.27) 0.90 (0.82–0.97) 97.7% (87.7%–99.9%) 4.7% (1.8%–10.0%)

*Tp-PCR, Treponema pallidum PCR; DFM, darkfield microscopy; PPV, positive predictive value; NVP, negative predictive value.

Main Article

1Preliminary results from this study were presented at the 53rd Interscience Conference on Antimicrobial Agents and Chemotherapy, September 10–13, 2013, Denver, Colorado, USA.

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