Diagnosis of Bacterial Vaginosis with Relation to Isolation of Gardnerella vaginalis

Yang, Nam Woong; Sin, Sung Heui; Chang, Jung Soo

Abstract

Among 104 patients who visited a local clinic with increased, bad-smelling vaginal discharge, twenty-nine women (27.9%) were found to have bacterial vaginosis (BV) according to the Amsel's composite clinical criteria (homogeneous thin gray discharge, positive amine test, vaginal pH over 4.5, positivity of clue cell by Gram stain). The specificity, sensitivity and positive and negative predictive values of the Amsel's composite clinical criteria were estimated in relation to the G. vaginalis isolation rate. Fifty-two strains of G. vaginalis (50%) were isolated from vaginal swabs taken from 104 patients. The sensitivities of clue cells and G. vaginalis isolation were both 96.6% (28) in the 29 BV patients. The specificities of clue cells and the presence of G. vaginalis were 85.3% and 68.0%, respectively. But the sensitivity, specificity, and positive and negative predictive values of the combination of clue cells and morphotype of G. vaginalis were 93.1%, 92.0%, 81.8% and 97.2%, respectively. The sensitivity, specificity and positive and negative predictive values of amine test were 89.7%, 98.7%, 96.2% and 94.9% in the 29 BV patients. Among 52 strains of G. vaginalis, 34 strains (87.2%) were isolated from the 39 clue cell positive samples and the remaining 18 (27.7%) from the 65 clue cell negative cases. Twenty-four strains (92.3%) were isolated from 26 amine test positive samples and the remaining 28 (35.9%) from 78 amine test negative cases. According to these results, it seems that the amine test is a useful test for the diagnosis of BV. However, we propose the combination criteria of clue cells and G. vaginalis morphotype in vaginal discharge should give more objective results than the amine test for the diagnosis of BV. The sensitivity and specificity of vaginal pH over 4.5 were 86.2% and 57.3%, and those of homogeneous discharge 93.1% and 65.3%, respectively. These two criteria were not as specific as clue cells and amine test for the diagnosis of BV. These results suggest that BV could be diagnosed more simply and precisely with the finding of clue cells spotted with Gram variable polymorphic bacteria by means of Gram stain of vaginal wall swabs.