Evaluation of an enzyme-linked immunoassay and confirmatory test for the detection of Chlamydia trachomatis in male urine samples.

First pass urine (FPU) samples were compared with urethral swab culture from 304 males attending a genitourinary medicine clinic using an enzyme immuno assay (EIA). All of the EIA positive samples were retested by incorporating a novel blocking reagent into the EIA protocol; 101 were positive by culture of which 83 were also positive by FPU EIA, an additional four were detected in FPU only and not by culture; 86 of these 87 were also confirmed positive by the blocking reagent. Discrepant results were evaluated by Syva MicroTrak. The sensitivity and specificity of FPU EIA as compared with urethral swab culture was 82.2% (83/101) and 98% (199/203) respectively with positive and negative predictive values of 95.4% (83/87) and 91.7% (199/217). Male urethral swab culture is more sensitive than FPU EIA; however, when culture is not available then FPU offers a reliable non-invasive alternative to swab EIA which may be of enormous benefit in community screening of asymptomatic as well as symptomatic patients.