Detection of Chlamydia trachomatis DNA in patients with non-gonococcal urethritis using the polymerase chain reaction.

A practical protocol using the polymerase chain reaction (PCR) was designed for detecting Chlamydia trachomatis in clinical samples. DNA was extracted from material collected on urethral swabs and used as substrate for the PCR. The target was a 600 basepair DNA segment of the multicopy plasmid that is common to all strains of the bacterium. Negative samples were checked for loss of DNA or presence of polymerase inhibitors by a second PCR, targeted to a conserved segment of the human genome. The whole procedure was tested on 216 men with non-gonococcal urethritis (NGU). All patients were independently assessed by tissue culture isolation (60 positive samples) and a commercial immunoenzymatic assay. The PCR protocol, while sufficiently simple for routine application, was reliable and, for the diagnosis of urethritis, at least as good as tissue culture isolation.