Diagnostic Evaluation of a Multiplex Quantitative Real-Time PCR Assay forBacterial Vaginosis

Abstract

Background: Quantitative multiplex PCR assay for Bacterial Vaginosis (BV) based on the detection of the predominant contributory targets was evaluated against the conventional Nugent Score that is laborious and subjective due to morphological assessment bias of BV-associated bacteria. Methods: 125 dual vaginal specimens were collected from patients aged ≥18 years at the time of presentation at the provider office to perform real time PCR and Nugent Testing. PCR assessment of BV was performed by quantitation of DNA amounts of Gardnerella vaginalis, Atopobium vaginae, Lactobacillus spp., and total amount of bacterial DNA using a multiplex RT-PCR kit (ATRiDA, Netherlands). Discordant results were resolved by the Amsel criteria or ancillary testing such as BD Affirm, when available. Results: Nugent score classified 36.36% of the patients in BV and 15.45% in transitional BV categories. In contrast, the PCR method called 48.18% as BV and 12.72% as transitional BV or BV of unspecified origin categories. The overall concordance between the two methods was 81.81%. None of the BV positives by Nugent method were missed by the PCR. There were only 2 intermediates by Nugent that were called normal by PCR. PCR method was more sensitive than the Nugent and picked an additional 11% positives. Conclusions: PCR based molecular BV diagnosis can standardize women health testing by removing the bias due to subjective interpretation of Nugent scoring. Our study shows that PCR method is more sensitive than conventional testing and may be a promising replacement for laborious Nugent scoring method in an era of shrinking microbiology expertise.