A simple ELISA capable of distinguishing between IgG antibodies to Chlamydia trachomatis and Chlamydia pneumoniae

Simple assays which reliably distinguish between past infection with Chlamydia pneumoniae and with Chlamydia trachomatis are needed. We developed an enzyme-linked immunosorbent assay (ELISA) for this purpose by reducing antigen cross reactive lipopolysaccharide epitopes with deoxycholate treatment and releasing antibodies of low affinity with a 6 M urea wash step. Paired serum samples from 212 patients with non-C. pneumoniae-associated community acquired pneumonia and single serum samples from 61 healthy students, 61 women with gynaecological complaints, and 100 blood donors were tested in the assay system. Excellent positive/negative correlation with the microimmunofluorescence (MIF) test was shown. This urea ELISA assay may be useful in assessment of past infection with these organisms, especially in epidemiological studies.