Chlamydia trachomatis IgM test methodology is Enzyme-linked immunosorbent assay (ELISA) which has the ability to detect the IgM antibody even after several months of infection. The test involves coating the microwells surface with purified Chlamydia antigen which binds the antibody to itself if present in the diluted serum sample. The colour generated after washing off the excess enzyme substrate gives the actual result of the test.