Direct detection of Chlamydia trachomatis in clinical specimens by a dot-immunobinding technique using monoclonal antibody

A dot-immunobinding technique (DIBT) has been developed to permit detection of Chlamydia trachomatis organisms or antigen in clinical specimens. This method was evaluated for the rapid diagnosis of chlamydia infections using monoclonal antibody. The membrane antigen extracted from reticulate bodies was used for the production of species-specific monoclonal antibodies by an in vitro immunization procedure. The DIBT involved spotting clinical specimen directly onto a nitrocellulose membrane followed by reaction with monoclonal antibody and a biotin-avidin-peroxidase indicator system. Specimens were tested for the presence of chlamydia by the cell culture method. Of these, 361 positives and 317 negatives were selected for detection of antigen using the DIBT method. Of 678 clinical specimens that were evaluated by DIBT, 654 (96.7%) gave identical results to the cell culture method, whereas 24 (3.5%) were positive by the DIBT but culture negative. The overall sensitivity was 100% with a specificity of 92.4%. The test could detect as little as 75 pg of chlamydial antigen.