Head-to-Head Comparison of Second-Generation Nucleic Acid Amplification Tests for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae on Urine Samples from Female Subjects and Self-Collected Vaginal Swabs

Abstract

f In a comparison of 4 second-generation nucleic acid amplification tests performed with self-collected vaginal swab (SCVS) and first-void urine (FVU) specimens from 575 women, SCVS specimens indicated more infections than did FVU specimens in all assays. The prevalence rates were 9% (53/575 patients) for Chlamydia trachomatis and 2% (11/575 patients) for Neisseria gonorrhoeae. The clinical sensitivities for testing SCVS specimens for C. trachomatis were 98.1% on a Tigris system and 96.2% on a Panther system for the Aptima Combo 2 assay (Hologic Gen-Probe), 98.0% for the RealTime CT/NG assay on an m2000 instrument (Abbott), 90.6% for the ProbeTec CT/GC Q x assay on the Viper system (Becton Dickinson), and 84.6% for the cobas CT/NG assay on the cobas 4800 platform (Roche). Clinical sensitivities for C. trachomatis in FVU specimens were 88.7% (Tigris) and 88.0% (Panther) for the Aptima Combo 2 assay, 76.9% for the RealTime CT/NG assay, 75.5% for the ProbeTec CT/GC Q C hlamydia trachomatis and Neisseria gonorrhoeae infections of the female genital tract present a diagnostic challenge because many patients are asymptomatic (1, 2). This has led to implementation of screening strategies using less-invasive sampling procedures (3, 4), and screening programs often increase the number of samples received in the laboratory (5). Nucleic acid amplification tests (NAATs) for C. trachomatis and N. gonorrhoeae diagnosis have been available from commercial sources for over 15 years. The first PCR assay from Roche was the semiautomated Amplicor CT/NG test (6), which evolved into the automated cobas Amplicor assay. The ligase chain reaction assay (Abbott LCX) was the second NAAT to be used extensively but was withdrawn globally in 2003. A first-generation strand-displacement assay called ProbeTec ET, from Becton Dickinson, became available for evaluation in 1999. During the same time frame, a first-generation transcription-mediated amplification test was developed by GenProbe and evolved into the second-generation Gen-Probe Aptima Combo 2 (AC2) assay, which was evaluated with female specimens and was reported in 2003 (7). More recently, the U.S. Food and Drug Administration (FDA) cleared three additional secondgeneration assays and automated instruments, namely, the Abbott Molecular RealTime CT/NG assay on the m2000 instrument, the Becton Dickinson ProbeTec CT/GC Q x assay on the Viper XTR instrument, and the Roche Diagnostics cobas CT/NG assay on the cobas 4800 instrument.Examination of the package inserts for these newer secondgeneration assays indicated that FDA clearance was granted by comparing the new assays with patient-infected status (PIS) results, with infection being based on positive results from at least two cleared assays when 2 different specimen types were tested.The cobas CT/NG assay was compared with two other secondgeneration assays (AC2 and ProbeTec CT/GC Q x assays) (8, 9). The AC2 test and the first-generation ProbeTec ET assay were chosen for the RealTime CT/NG performance studies (10) and the ProbeTec CT/G...

Azithromycin versus Doxycycline for UrogenitalChlamydia trachomatisInfection

“…Second, urine specimens were used for chlamydia nucleic acid amplification testing in female participants. During the course of the study, vaginal swabs become the preferred specimen for chlamydia screening by means of nucleic acid amplification testing, 30 in part because of the slightly higher sensitivity of this type of testing when vaginal swab samples are used 31 ; however, we continued to test urine specimens for comparison purposes, and it is possible that a small number of infections were undetected. Third, an unexpected challenge in our study was the high rate of early discharge from youth correctional facilities; this may have been due in part to changing trends in juvenile justice policies leading to fewer and shorter incarcerations.…”

A recommendation for timing of repeat Chlamydia trachomatis test following infection and treatment in pregnant and nonpregnant women

“…Nucleic acid amplification tests (NAATs) are the recommended diagnostic test for diagnosis and repeat testing given their superior sensitivity and specificity when compared to culture for the detection of urogenital chlamydial infections. 2,6,7 …”

Workflow and Maintenance Characteristics of Five Automated Laboratory Instruments for the Diagnosis of Sexually Transmitted Infections

“…With clearance by the U.S. Food and Drug Administration and other regulatory agencies in Europe and elsewhere of several systems, automated molecular testing has become routine in clinical laboratory practice, ensuring diagnostic accuracy and improved result turnaround time (TAT). Studies have been published assessing clinical performances of molecular assays (2)(3)(4)(5)(6)(7)(8), and workflow and maintenance characteristics of automated instruments (9)(10)(11)(12)(13)(14)(15)(16). In addition to performance and instrumentreagent costs, hands-on time required for testing and maintenance, in-process interaction, and time to results and test capacity are key metrics that should be considered because they can influence efficiency and labor costs.…”

“…For this purpose, the respective second-generation assays for C. trachomatis and N. gonorrhoeae were used to process 96 and 192 tests on each instrument. A related study (8) compared the diagnostic performance of these assays for C. trachomatis and N. gonorrhoeae on self-collected vaginal swabs and first-void urine samples on the respective automated instruments.…”