Direct diagnosis of Chlamydia trachomatis genital tract infections: culture or PCR?

PCR and culturing were compared for the routine diagnosis of Chlamydia trac homatis infections. Two laboratories experienced in both techniques partici pated in the study, which included 513 specimens. Both techniques were perf ormed on each specimen; the portion of the specimen used for PCR was divide d in two, and each half was sent to one of the two laboratories, where the tests were run in a blinded fashion. The PCR primers used by the two labora tories matched different parts of the bacterial genome. PCR inhibitors were looked for in all specimens. Overall, PCR was more sensitive than culturin g; the difference was marked for sperm and endopelvic specimens and nonsign ificant for urethral and cervical specimens. False-positive PCR results wer e few in number, there were no consistent false-positive results when each specimen was amplified twice. PCR inhibitors were rarely present in urethra l and cervical specimens but were found in 7% of sperm and endopelvic speci mens. PCR inhibitors should be looked for routinely during PCR testing of s perm or endopelvic specimens.