Deciphering Intermediate Nugent scores: Utility of Real-time PCR for Bacterial Vaginosis diagnosis

Abstract

PurposeTo optimize real-time PCR assays for diagnosis of Bacterial Vaginosis (BV) and determine cut-off loads by ROC analysis for Gardnerella vaginalis, Atopobium vaginae and Lactobacillus spp. as compared to Nugent scoring (Gold standard) in clinical samples. ResultsOut of 125 women, 34 were positive, 26 intermediate and 65 negative for BV by Nugent scoring. All three real-time PCR assays were found to be highly sensitive & specific and AUC suggested excellent diagnostic accuracy. An optimal cut-off was >9.45 × 103 copies/ ml, >3.34 × 103 copies/ ml & ≤ 18.63 × 103 copies/ ml for G. vaginalis, A. vaginae and Lactobacillus spp. respectively, in BV positives. Gram staining and qPCR were discordant only in patients with intermediate scores (n = 26) where qPCR identified 15 (57.69%) as positive and 11 (42.3%) as negative. ConclusionPCR-based molecular BV diagnosis is more accurate and can be used for deciphering intermediate Nugent scores.