Evaluation of the BD ProbeTec ET System for Chlamydia trachomatis and Neisseria gonorrhoeae Infections of the Endocervix and Oropharynx in Women

OBJECTIVES: To determine the performance of a real-time DNA amplification assay, BD ProbeTec ET System (BDPT, BD Diagnostic Systems), for the detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) from both endocervical and oropharyngeal samples. METHODS: Swab samples were collected from women attending an OB/GYN clinic at each of six study sites. Endocervical swab samples were assayed by BDPT and Amplicor (AMP, Roche). Oropharyngeal swab samples were assayed by BDPT and DNA probe (Gen-Probe). For the oropharyngeal swab samples, discordant results for CT were confirmed by AMP and discordant results for GC were confirmed by established PCR methods as follows, cpp B PCR, nested cpp B PCR, and 16S rRNA PCR. RESULTS: A total of 364 endocervical and 247 oropharyngeal specimens were collected under informed consent from 364 patients. The agreement rates of the BDPT and AMP assays for the detection of CT and GC from endocervical samples were 99.2% (361/364) for CT and 99.5% (362/364) for GC. For oropharyngeal swabs the BDPT yielded 21 CT positives. Of these, 19 samples were CT negative by DNA probe. Using AMP, 16/19 (84.2%) of the BDPT+/DNA probe-samples were positive. The BDPT also yielded 21 GC positives of which 15 samples were negative by DNA probe. After additional testing 14/15 BDPT+/DNA probe-samples (93.3%) were positive by at least two of the PCR methods. CONCLUSIONS: The BDPT performs comparably to AMP for detection of CT and GC from endocervical swab samples. Because the DNA probe method is low in sensitivity, the BDPT yielded several additional positive results on oropharyngeal swab samples. Further analysis using alternative methods of DNA amplification illustrated the BDPT to be more sensitive than DNA probe and that it may be clinically useful for the detection of CT and GC from oropharyngeal samples.