Enzyme-linked immunosorbent assay for detecting gonococcal antibodies using two antigenically different gonococcal pili as antigen.

Antibodies to pilar antigens of two gonococcal strains isolated in Rotterdam (6650 and 1443) were detected using enzyme-linked immunosorbent assays (ELISA). Paired sera (the first sample taken at the first examination (D1) and the second 11-22 days later (D2)) from women with and without gonorrhoea attending a sexually transmitted disease (STD) clinic were studied. The sensitivity of the ELISA using gonococcal pili 6650 as antigen (ELISA 6650) was significantly higher than that using gonococcal pili 1443 as antigen (ELISA 1443). The specificity of the two tests differed little. On D1 the sensitivity in women with uncomplicated gonorrhoea was 69% in the ELISA 6650 and 45% in the ELISA 1443; the corresponding values in asymptomatic infected women were 75% and 57% respectively. The agreement (both in positive and in negative results) between the two tests was less than might have been expected (kappa = 0.41).