C-164. Detection of Chlamydia trachomatis and Neisseria gonorrhoeae on Endocervical and Vaginal Swabs with the BD ProbeTec™ CTQx and GCQx Amplified DNA Assays on the BD ViperTM System in Extracted Mode

T. Brink, J. Harris, T. Schlitzer, J. Kendall, C. Welborn, S. Giles, C. Martinaitis;
Becton Dickinson, Sparks, MD.

We have developed two novel assays for detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) for use with the BD Viper™ System in extracted mode. Walk-away automation is achieved through the extraction of DNA from clinical specimens by binding to ferric oxide, followed by amplification and real-time fluorescent detection. In addition, the BD ProbeTec™ CT/GC Qx Amplifed DNA Assays incorporate an Extraction Control (EC) to verify that proper conditions exist for DNA extraction. Here we describe the analytical performance of these assays on the BD Viper System with vaginal and endocervical swabs. The analytical sensitivity of the CT/GC Qx assays was determined by spiking endocervical and vaginal swab matrices with CT serovar H (ATCC™ VR-879H UW-43/Cx) and GC (ATCC 19424) at six different target levels (N=72/level), followed by DNA extraction and amplification on the BD Viper System. The Limit of Detection (LOD) was defined as the level at which 95% of the samples yielded a positive result. The stability of CT and GC DNA on dry vaginal swabs (pre-and post expression) and ‘wet’ endocervical swabs in Qx Swab Diluent was established by co-spiking specimens with CT and GC at a low level near the analytical limits of detection of the assays in expressed swab matrix, followed by storage at 2-8 or 30°C.
The table below summarizes the analytical LODs for the CTQx and GCQx assays.

 

LOD (95% Confidence Intervals)

 

Endocervical Swab

Vaginal Swab

CTQx (EB/mL)

15 (12, 20)

13 (8, 21)

GCQx
(particles/mL)

44 (28, 71)

64 (43, 95)


CT and GC DNA were stable for up to 30 days in the post-expressed vaginal and endocervical matrices when stored at 2-30°C. Under the same temperature conditions, CT and GC DNA were also stable for up 14 days on dry vaginal swabs. When integrated with automated DNA extraction on the BD Viper System, the BD ProbeTec CT/GC Qx Amplified DNA Assays have the potential to detect low numbers of organisms on endocervical and vaginal swabs. The collection and transport systems for these specimen types also offer flexibility to the user over a broad range of shipping and storage conditions.
*Product not for sale, for investigational use only in the US.