Multicenter evaluation of the fully automated COBAS AMPLICOR PCR test for detection of Chlamydia trachomatis in urogenital specimens

The fully automated COBAS AMPLICOR CT/NG test for the detection of Chlamydi a trachomatis was evaluated in a multicenter trial. Test performance was ev aluated for 2,014 endocervical swab and 1,278 urine specimens obtained from women and for 373 urethral swab and 254 urine specimens obtained from men. Culture served as the reference test. Culture-negative, COBAS AMPLICOR-pos itive specimens that tested positive in a confirmatory PCR test for an alte rnative target sequence within the C. trachomatis major outer membrane prot ein gene were resolved as true positives. The overall prevalence of chlamyd ia was 4.3% in cervical swabs and 11.0% in urethral swabs from men. When th e results for each specimen type were considered separately the resolved se nsitivities were 96.5% (83 of 86) for endocervical swab specimens, 95.1% (3 9 of 41) for urine specimens from women, 100.0% (41 of 41) for urethral swa b specimens from men, and 94.4% (17 of 18) for urine specimens from men; th e resolved specificities were 99.4% (1,912 of 1,924) for endocervical swab specimens, 99.8% (1,204 of 1,207) for urine specimens from women, 98.5% (32 5 of 330) for urethral swab specimens from men, and 100.0% (236 of 236) for urine specimens from men. For the subset of patients from whom both swab a nd urine specimens were collected, the combined results for both specimen t ypes were used to identify all infected patients. Using these combined resu lts as criteria, the resolved sensitivities for the COBAS AMPLICOR test wer e 82.6% (38 of 46) for endocervical swab specimens, 84.4% (38 of 45) for ur ine specimens from women, 84.2% (16 of 19) for urethral swab specimens from men, and 89.5% (17 of 19) for urine specimens from men. In comparison, the sensitivity of culture was only 56.5% (26 of 46) for endocervical specimen s and 63.2% (12 of 19) for urethral specimens from men. The internal contro l provided in the COBAS AMPLICOR test revealed that 2.9% of specimens were inhibitory when they were initially tested. Nevertheless, valid results wer e obtained for 99.1% of specimens because 68.7% of the inhibitory specimens were not inhibitory when a second aliquot of the original sample was teste d. Two additional COBAS AMPLICOR-positive specimens were detected by retest ing inhibitory specimens. The COBAS AMPLICOR CT/NG test for the detection o f C. trachomatis exhibited equally high sensitivities and specificities wit h both urogenital swab and urine specimens and, thus, is well-suited for us e in screening.