Introduction: Currently only urine and swab samples are validated on the Roche Cobas 4800 CT/NG PCR Test. Semen samples are another sample type that requires testing for various pathogens including Chlamydia trachomatis (C. trachomatis). With no approved validated test currently available for C. trachomatis semen testing, laboratories must evaluate existing platforms. Cobas Amplicor system has been shown to be suitable for molecular detection of C. trachomatis in semen however the instrument has been superseded by the Roche Cobas 4800. We evaluated the ability of the Cobas 4800 to detect C. trachomatis seeded in semen samples compared to Cobas Amplicor.
Methods: Serial ten-fold dilutions of pooled negative semen were seeded with C. trachomatis serovar J, and were processed for Cobas 4800 CT/NG test by adding 200uL of each dilution to 1.3mL SPEX (Roche specimen pre-extraction reagent). The semen-SPEX dilutions were extracted on Cobas x480 according to the urine processing protocol and then tested on Cobas z480. Simultaneously, 200uL of each dilution was extracted using MagNA Pure 96 and then tested on Cobas Amplicor CT/NG test. Dilutions 1:104 to 1:107 were tested in duplicate by both assays.
Results: C. trachomatis was detectable equally at dilution 1:104 by both Cobas 4800 and Cobas Amplicor.
Discussion: Cobas 4800 results showed good correlation when compared to Cobas Amplicor results indicating suitability of x480 for semen processing for C. trachomatis detection.