Abstract

Chlamydia trachomatis, a member of the Chlamydiaceae, is the most common cause of bacterial sexually transmitted infections worldwide. The application of real-time polymerase chain reaction (PCR) in laboratory diagnostic testing for C. trachomatis is becoming increasingly popular. Modern approaches sometimes involve a combination of different test technologies for screening and confirmation; this indeed is a Clinical Pathology Accreditation (CPA) recommendation. Multiple real-time PCR platforms and assays are currently available, each of which comes with slight variation in their performances. Before incorporating any of these into routine clinical use, accuracy and reliability must be assessed. This study evaluated the performance characteristics of the Cepheid SmartCycler used in conjunction with the EuroClone Duplicareal time Dual Easy CT assay for the confirmation of Roche COBAS TaqMan positive tests by comparing results obtained by each method. Consecutive clinical C. trachomatis positive (n = 67) and random negative (n = 17) urogenital samples received at a general district hospital in the North East of England over a 6-month period were examined. Of the total 67 TaqMan-positive samples, 62 (92.5%) of them were also positive by the SmartCycler/EuroClone. There were 5 discrepancies in total (7.5%) and 17 samples were negative on both Roche TaqMan and SmartCycler/EuroClone. The sensitivity and specificity of the method were 92.5 and 100%, respectively. To further assess its specificity, the SmartCycler/EuroClone method was challenged with additional organisms and proved to possess the ability of avoiding false-positive results by correctly identifying these as C. trachomatis DNA negative. Finally, it was found that confirmation of positive C. trachomatis by the SmartCycler/EuroClone method increases the turn around time of chlamydia investigation by 2-folds. In conclusion, the SmartCycler/EuroClone method gave good concordance with the established Roche TaqMan method and proved to be highly suitable for confirmation testing of C. trachomatis positive samples. The remarkable specificity and acceptable sensitivity also confirms its suitability and reliability for this purpose.