Enzyme immunoassay and direct immunofluorescence for detection of Chlamydia trachomatis antigen in male first-void urine.

First-void urine specimens, collected from 309 military recruits, 246 male adolescent gymnasium students and 194 patients consulting venereal disease clinics, were studied for the presence of Chlamydia trachomatis with the use of antigen detection tests--two enzyme immunoassays (EIA) and a direct immunofluorescence test (DIF; Syva MicroTrak). Urethral swabs were collected when discrepancies between the EIA and DIF tests were detected. The patient was regarded as positive when the culture result was positive or when two antigen detection tests corraborated one another. The Syva MicroTrak EIA and DIF tests were more sensitive than the Orion EIA, i.e. 98.5%, 99.2% and 74%, respectively. This was true when testing both low- and high-risk groups, with a prevalence of chlamydial infection ranging from 0.4% to 58.6%. All three tests were highly specific. The positive predictive values for the Syva MicroTrak EIA, the DIF and the Orion EIA were 99.2%, 100% and 100%, respectively and the negative predictive values 99.8%, 99.8% and 94.8%, respectively.