Multicenter evaluation of AMPLICOR and automated COBAS AMPLICOR CT/NG tests for Neisseria gonorrhoeae

The fully automated COBAS AMPLICOR CT/NG and semiautomated AMPLICOR CT/NG; tests were evaluated in a multicenter trial for their ability to detect Nei sseria gonorrhoeae infections, Test performance compared to that of culturi ng was evaluated for 2,192 matched endocervical swab and urine specimens ob tained From women and for 1,981 matched urethral swab and urine specimens o btained from men. Culture-negative, PCR-positive specimens that tested posi tive in a confirmatory PCR test for an alternative target sequence within t he N. gonorrhoeae 16S rRNA gene were considered to be true positives. The o verall prevalences of gonorrhea were 6.6% in women and 20.1% in men. The CO BAS AMPLICOR and AMPLICOR formats yielded concordant results for 98.8% of t he specimens and exhibited virtually identical sensitivities and specificit ies. The results that follow are for the COBAS AMPLICOR format. With the in fected patient as the reference standard, the resolved sensitivities of PCR were 92.4% for endocervical swab specimens and 64.8% for female urine spec imens. There were no significant differences in these rates between women w ith and without symptoms, Among symptomatic men, COBAS AMPLICOR sensitiviti es were 94.1% for urine and 98.1% for urethral swabs; for asymptomatic men, the results were 42.3 and 73.1%, respectively, In comparison, the sensitiv ities of culturing were 84.8% for endocervical specimens, 92.7% for symptom atic male urethral specimens, and only 46.2% for urethral specimens obtaine d from asymptomatic men. When PCR results were analyzed as if only a single test had been performed on a single specimen type, the resolved sensitivit y,ias always higher. The resolved specificities of PCR were 99.5% for endoc ervical swab specimens, 99.8% for female urine specimens, 98.9% for male ur ethral swab specimens, and 99.9% for male urine specimens. The internal con trol revealed that 2.1% of specimens were inhibitory when initially tested. Nevertheless, valid results were obtained for 99.2% of specimens because 6 0.0% of the inhibitory specimens were not inhibitory when a second aliquot was tested. The COBAS AMPLICOR CT/NG test for N. gonorrhoeae exhibited high sensitivity and specificity with urethral swab and urine specimens from me n and endocervical swab specimens from women and thus is well suited for di agnosing and screening for N, gonorrhoeae infection.