Multicenter evaluation of the AMPLICOR and automated COBAS AMPLICOR CT/NG tests for detection of Chlamydia trachomatis

The fully automated COBAS AMPLICOR CT/NG and semiautomated AMPLICOR CT/NG t ests were evaluated in a multicenter trial for the ability to detect Chlamy dia trachomatis infections. Test performance compared to that of culture wa s evaluated for 2,236 matched endocervical swab and urine specimens obtaine d from women and for 1,940 matched urethral swab and urine specimens obtain ed from men. Culture-negative, PCR-positive specimens that tested positive in a direct fluorescent-antibody test or in a confirmatory PCR test for an alternative target sequence were resolved as true positives. The overall pr evalences of chlamydia were 2.4% in women and 7.2% in men. The COBAS AMPLIC OR and AMPLICOR formats yielded concordant results for 98.1% of the specime ns. With the infected patient as the reference standard, the resolved sensi tivities of COBAS AMPLICOR were 89.7% for endocervical swab specimens, 89.2 % for female urine specimens, 88.6% for male urethral swab specimens, and 9 0.3% for male urine specimens. When results were analyzed as if only a sing le test had been performed on a single specimen type, the resolved sensitiv ity was always higher. The resolved specificities of PCR were 99.4% for end ocervical swab specimens, 99.0% for female urine specimens, 98.7% for male urethral swab specimens, and 98.4% for male urine specimens. The internal c ontrol revealed that 2.4% of the specimens were inhibitory when initially t ested. Nevertheless, valid results were obtained for 98.6% of the specimens because 59.1% of the inhibitory specimens were not inhibitory when a secon d aliquot was tested. The COBAS AMPLICOR and AMPLICOR CT/NG tests for C. tr achomatis exhibited equally high sensitivity and specificity with both urog enital swab and urine specimens and thus are well suited for screening for C. trachomatis infection.