The significance of the secretory immunoglogulin A to Gardnerella vaginalis in the pathogenesis and diagnosis of bacterial vaginosis

Background: Although bacterial vaginosis is prevalent, not much progress has occurred in identifying the factors which are responsible and are associated with bacterial vaginosis and its pathophysiology. Studies on the development of better methods for the diagnosis of bacterial vaginosis are still on. Objective: To estimate the levels of secretory immunoglobulin A (sIgA) antibodies against G.vaginalis in vaginal discharge and its correlation with the clinical condition. Materials and Methods: We developed an indirect ELISA by using whole cell antigen to detect sIgA antibodies against G.vaginalis in vaginal washings which were collected from 170 women who attended two hospitals in south India for antenatal care or any other complaint. The women were categorised into bacterial vaginosis, intermediate and normal by using Nugent's criteria. Statistical analysis was done by using the Chi- Square test, analysis of variance and Scheffe's multiple range tests, as appropriate. Results: Of the 170 women under study, 42 were cases of bacterial vaginosis, 30 had intermediate flora and 98 were normal women. Of the 42 women with bacterial vaginosis, 16 (38%) showed a significantly high titre and 26 (62%) had low titre. Of the 30 women with intermediate flora, 10 (33.3%) showed a significantly high titre and 20 (66.7%) had low titres of the 98 women with normal flora, 84 (85.7%) showed low titres and 14 (14.3%) showed high titres of sIgA antibodies against G.vaginalis. The results of the ELISA test correlated statistically with the cases of bacterial vaginosis when analysed by Chi-Square test (p < 0.05). Analysis of variance showed that there was significant variation (p < 0.05) between the titers of sIgA antibodies detected in the women categorised by Nugent's criteria. Conclusion: All the women with bacterial vaginosis or with intermediate flora do not show significant titres of sIgA antibodies to G.vaginalis. So, the detection of sIgA to G.vaginalis in the vaginal discharge cannot be used as a means for the diagnosis of bacterial vaginosis.