Background:
We have developed two novel assays for the detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) on the BD ProbeTec ET system that amplify different target sequences than the existing BD ProbeTec ET CT/GC Amplified DNA Assays. In addition, the new Q^x CT/GC assays incorporate Internal Amplification Controls to monitor sample inhibition and verify that proper amplification conditions exist for each specimen. Here we describe the performance of these assays with vaginal swabs as a novel sample type for the diagnosis of CT and GC infections.

Objective:
To investigate the performance of the CT/GC Q^xassays with the new BD ProbeTec^TM Vaginal Specimen Transport.

Method:
Analytical sensitivity: Vaginal swab matrix spiked with various levels of CT and GC, processed and tested.
Specimen stability: Concentrated pool of expressed vaginal swabs spiked with CT and GC at approximately 2X their respective limits of detection, and seeded onto swabs that were stored under different conditions.
Clinical performance: Paired endocervical and vaginal swab specimens were evaluated from approximately 795 patients and 3 clinical sites.


Result:
Analytical sensitivity: CT = 43 Elementary Bodies/mL; GC = 75 particles/mL.
Stability: Both organisms were stable on seeded swabs for 30 days at 2-8°C and –20°C, and for 14 days at 30°C.
Positive Percent Agreement: CT = 98.7%; GC = 100%
Negative Percent Agreement: CT = 98.9%; GC = 99.3%
Indeterminate rate: CT = 0.1%; GC = 0%.


Conclusion:
The BD ProbeTec ET CT/GC Q^x Assays have the potential to detect low numbers of organisms on vaginal swabs. Good positive and negative agreements were obtained between vaginal swabs and conventional endocervical specimens.

Implications:
When used with the CT/GC Q^x assays, vaginal swabs may provide a convenient alternative to conventional endocervical and urine specimens for the detection of CT and GC on the BD ProbeTec^TM ET System.