Comparison between Gram stain and culture for the characterization of vaginal microflora: Definition of a distinct grade that resembles grade I microflora and revised categorization of grade I microflora
(1) Department Clinical Chemistry, Microbiology Immunology, Ghent University Hospital, UGent, Ghent, Belgium;(2) Department of Obstetrics Gynaecology, Ghent University Hospital, UGent, Ghent, Belgium
Abstract:
Background
The microbiological diagnosis of bacterial vaginosis is usually made using Nugent's criteria, a useful but rather laborious
scoring system based on counting bacterial cell types on Gram stained slides of vaginal smears. Ison and Hay have simplified
the score system to three categories and added a fourth category for microflora with a predominance of the Streptococcus cell type. Because in the Nugent system several cell types are not taken into account for a final score, we carried out a
detailed assessment of the composition of the vaginal microflora in relation to standard Gram stain in order the improve the
diagnostic value of the Gram stain. To this purpose we compared Gram stain based categorization of vaginal smears with i)
species specific PCR for the detection of Gardnerella vaginalis and Atopobium vaginae and with ii) tDNA-PCR for the identification of most cultivable species.