Specific immune response against Gardnerella vaginalis hemolysin in patients with bacterial vaginosis

Our goal was to study the mucosal host response in bacterial vaginosis by evaluating the presence of a specific immune response elicited against the Gardnerella vaginalis hemolysin in vaginal fluids of patients and by verifying its correlation with usual criteria adopted to diagnose bacterial vaginosis.

A total of 123 white women attending the gynecologic care unit for urogenital complaints or for screening of uterine malignancies (Papanicolaou test) aged from 20 to 60 years, nonmenstruating, were enrolled. Bacterial vaginosis was diagnosed by clinical criteria and a Gram stain score > 6.

We performed the determination of the antibody response in vaginal fluid against the hemolysin produced by G. vaginalis, a common agent present in bacterial vaginosis. The purified G. vaginalis toxin was a suitable antigen for detecting the presence of an immune response in the vaginal fluids of patients with bacterial vaginosis regardless of the strain of G. vaginalis present. A specific immunoglobulin A response was detected in 60% of women with overt bacterial vaginosis (Gram stain score > 6) and in 18.5% of women with intermediate vaginal flora (Gram stain score 4 to 6). The specificity of the test was 91%.

We found a correlation between the specific local immune response to G. vaginalis toxin and bacterial vaginosis. The highly purified form of the toxin is able to discriminate disorders from the opportunistic colonization by G. vaginalis.