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Diagnostic accuracy of quantitative real-time PCR assay versus clinical and Gram stain identification of bacterial vaginosis

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European Journal of Clinical Microbiology & Infectious Diseases Aims and scope Submit manuscript


The purpose of this investigation was to determine the diagnostic accuracy of quantitative real-time polymerase chain reaction (PCR) assay in diagnosing bacterial vaginosis versus the standard methods, the Amsel criteria and the Nugent score. The Amsel criteria, the Nugent score, and results from the molecular tool were obtained independently from vaginal samples of 163 pregnant women who reported abnormal vaginal symptoms before 20 weeks gestation. To determine the performance of the molecular tool, we calculated the kappa value, sensitivity, specificity, and positive and negative predictive values. Either or both of the Amsel criteria (≥3 criteria) and the Nugent score (score ≥7) indicated that 25 women (15%) had bacterial vaginosis, and the remaining 138 women did not. DNA levels of Gardnerella vaginalis or Atopobium vaginae exceeded 109 copies/mL or 108 copies/mL, respectively, in 34 (21%) of the 163 samples. Complete agreement between both reference methods and high concentrations of G. vaginalis and A. vaginae was found in 94.5% of women (154/163 samples, kappa value = 0.81, 95% confidence interval 0.70–0.81). The nine samples with discordant results were categorized as intermediate flora by the Nugent score. The molecular tool predicted bacterial vaginosis with a sensitivity of 100%, a specificity of 93%, a positive predictive value of 73%, and a negative predictive value of 100%. The quantitative real-time PCR assay shows excellent agreement with the results of both reference methods for the diagnosis of bacterial vaginosis.

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The authors thank Dr. Mireille Henry for her expertise in molecular biology, Stéphanie Junoy for her technical assistance, and Jo Ann Cahn for editing the manuscript.

Disclosure of interests

Université de la Méditerranée has applied for a patent on the quantitative molecular tool used in this study: European Patent Office no. 2087134.

Ethics approval

An Institutional Review Board (Ethics Committee of the University of Aix-Marseille, France) approved the study (in a decision dated September 19, 2008).

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Correspondence to J.-P. Menard.

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Menard, JP., Mazouni, C., Fenollar, F. et al. Diagnostic accuracy of quantitative real-time PCR assay versus clinical and Gram stain identification of bacterial vaginosis. Eur J Clin Microbiol Infect Dis 29, 1547–1552 (2010).

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