Abstract

An immune dot blot test (IDBT) to detect the genus specific lipopolysaccharide chlamydial antigen is described, in which the antigen is trapped on nitrocellulose membrane and then detected with a monoclonal antibody labelled with 125iodine. A preliminary comparison of 270 specimens obtained from the endocervix or male urethra showed that the IDBT was more sensitive (sensitivity 90%) than a commercial amplified enzyme immunoassay named IDEIA (sensitivity (60%) for detecting specimens that yielded Chlamydia trachomatis on culture. Subsequent assessment of 950 urogenital tract specimens in the IDBT and by culture confirmed the sensitivity (92%) and specificity (95%) of the IDBT. At least one of 56 specimens obtained from the eye, however, gave a false positive result, which was probably due to staphylococcal protein A in the specimen. The IDBT provides the basis for a novel simple test for detecting the genus Chlamydia.