Detection of Chlamydia trachomatis in urethral and urine samples from symptomatic and asymptomatic male patients by the polymerase chain reaction

Abstract

To evaluate the commercially available polymerase chain reaction (PCR) assay Amplicor (Roche Molecular Systems, USA) for diagnosis of Chlamydia trachomatis infection, urethral and urine swabs from a total of 344 male patients were tested and the results compared with those obtained by the nonisotopic hybridization assay Pace 2 (Gen Probe, USA) for urethral samples and by the enzyme immunoassay EIA MicroTrak (Syva, USA) for urine. Discrepant results were analyzed by a repeated test run using a major outer membrane protein-derived primer PCR, by the probe competition assay, and by the direct immunofluorescence test (DIF). Thirty-nine men (11.3%) were chlamydia positive, based on the results of all tests from both sampling sites. The rate of detection of chlamydia in urethral specimens by Amplicor and the Pace 2 was 79.5% and 61.5%, respectively, while the rate of detection in urine sediment was 75% for both Amplicor and EIA. In the first run of the PCR, a high number of false-negative results for unfrozen samples was observed, decreasing the sensitivity of Amplicor in urine to 47.3%. The results of the study indicate that Amplicor detects more infected individuals compared with other tests and is suitable as an alternative diagnostic test for chlamydia infections, using not only urethral specimens but also urine specimens. However, the finding of false-negative results when using Amplicor on unfrozen samples must be further investigated.