Background Roche cobas® 4800 system performs sample preparation, real-time PCR amplification and detection using an internal control in a single tube. The cobas® 4800 human papillomavirus (HPV) test is a multiplex assay that can detect HPV 16, HPV 18 and 12 other high-risk (12-HR) carcinogenic HPV genotypes. We compared this HPV test with the Linear Array (LA) HPV genotyping assay (Roche Molecular System). Therefore, this system can simultaneously detect Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in urine and swab specimens, and it was evaluated and compared with routine techniques in our clinical laboratory.
Methods 462 clinical samples collected in PresevCyt® liquid media were used for the HPV test study and compared using cobas® 4800 HPV test and LA-HPV. There were also included 688 clinical samples for CT and NG testing (206 urine samples only and 241 urine and swab specimens respectively) and compared with a real-time PCR assay for CT and bacteria culture for NG.
Results For the HPV analysis, 439 out of 462 samples examined (95%) showed positive (160 cases) and negative (302 cases) concordat results; the remaining 3 (0.65%) were invalid by the cobas® 4800 system. The positive samples were distributed: 26 samples of HPV 16, 4 of HPV 18, 110 of 12-HR and 20 samples with mixed infection (15 were 12-HR+HPV 16, four 12-HR+HPV 18 and one HPV 16+18). For CT/NG total analysis, there were only three invalid samples (0.43%) and only 4 (0.58%) discordant results. For the 206 urine samples, there were 19 CT positive, eight NG positive and two mixed CT and NG infections. These positive samples were from male with Chlamydia contact, urethritis and persons who was to STI control. For urine and swab specimens (241 of each), there were a total correlation between both types of samples. In total, there were 5% of positive samples corresponding to 13 CT positive, two NG positive and four mixed CT and NG infections. These positive samples presented clinical manifestations as urethitis or were women to get in touch with Chlamydia infected person.
Conclusions the cobas® 4800 system is an easy system for cervical HPV screening and to detect simultaneously CT and NG in a single tube. These test and our lab techniques correlated well in this analysis. Moreover, in the case of CT/NG test the correlation between urine and swab specimens was total, therefore to use urine as clinical sample to detect these two bacteria could be easier than to use swab specimens.