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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 2

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

Reference testing, n = 170 Sensitivity (95% CI) Specificity (95% CI) Likelihood ratios (95% CI)
κ coefficient Post-test probability (95% CI)
Positive Negative If Tp-PCR is positive (PPV) If Tp-PCR is negative (1 − NPV)
Tp-PCR 69.8% (53.9%–82.8%) 98.4% (94.4%–99.6%) 44.30 (11.05–177.68) 0.31 (0.20–0.48) 0.74 (0.62–0.87) 93.8% (79.2%–99.2%) 9.4% (5.6%–15.4%)
Enhanced definition 66.7% (51.6%–79.6%) 100.0% (96.9%–100.0%) 163.33 (10.2–2615.37) 0.33 (0.22–0.50) 0.74 (0.62–0.86) 100.0% (89.3%–100.0%) 11.6% (7.3%–18.0%)

*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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