C-155. Automated Multiplex Assay System for Simultaneous Detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC)

Q. Meng¹, D. Monga¹, C. Wong¹, N. Zhang¹, T. Kolachina¹, Z. Li¹, H. Li¹, J. Johnson¹, D. V. Ferrero², D. Sherman¹;
¹Siemens HealthCare Diagnostics, Inc., Berkeley, CA, ²Univ. of the Pacific, Stockton, CA.

Objective: The VERSANT^® CT/GC DNA 1.0 assay,* which can simultaneously detect Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) in swab and urine specimens, is run on the VERSANT™ kPCR Molecular System.* Analytical performance characteristics of the assay were evaluated. Methods: Bacterial DNA was extracted and captured nonspecifically from panels or patient specimens using silica-based magnetic particles on the VERSANT Sample Preparation (SP) Module. The purified DNA target was amplified and detected by kPCR on the Amplification/Detection (AD) Module. An internal control is incorporated in the assay to monitor the extraction, target amplification, and detection processes. The assay also includes a chemical contamination control (UNG). Assay sensitivity was determined by testing serial dilution panels prepared with heat-inactivated CT or GC cells in swab (M4RT) and urine. The ability of the assay to detect CT serovars and GC isolates was evaluated with 15 heat-inactivated CT serovar panels and 46 GC genomic DNA panels. Analytical assay specificity was evaluated with over 490 CT/GC-negative urine specimens and 59 different potentially cross-reactive organisms. A method comparison with Gen-Probe’s APTIMA was performed using over 470 clinical urine and swab specimens. Results: The assay yields qualitative results with discrimination of CT and GC targets. Detection limits for CT and GC targets are 600 and 295 copies/ mL in urine; and 455 and 275 copies/mL in swab. The assay detects a broad range of CT serovars and GC isolates. The assay demonstrated no false-positive results for both CT and GC with any of the 59 organisms tested. The specificity of the assay was 99% for the initial test, and 100% for the retest with confirmed negative urine specimens. The assay demonstrated over 98% agreement with Gen-Probe’s APTIMA assay. Conclusion: We present a new VERSANT CT/GC DNA 1.0 kPCR assay for simultaneously detecting CT and GC in swab and urine specimens. Preliminary analytical performance evaluation has demonstrated that the assay is highly sensitive and specific, with effective chemical contamination control and internal control.
* System and assay not yet commercially available.