Evaluation of the Abbott RealTi m e CT/NG Assay in Comparison to the Roche Cobas Amplicor CT/NG Assay

Abstract

Several commercial methods exist for the molecular detection of Chlamydia trachomatis and Neisseria gonorrhoeae in clinical samples. Here we evaluated the performance characteristics of the newly FDAcleared Abbott RealTime CT/NG assay (where "CT" stands for Chlamydia trachomatis and "NG" stands for Neisseria gonorrhoeae) that uses the automated m2000 molecular platform. Results were compared to those of the Roche Cobas Amplicor CT/NG assay. A total of 926 cervical swab, 45 female urine, 6 male urethral swab, and 407 male urine specimens from 1,384 patients were examined. After resolving all Roche N. gonorrhoeae-positive results with two additional real-time PCR assays, we found that the agreement between the assays was excellent. For urine samples, there was 99.6% positive agreement and 97.7% negative agreement for C. trachomatis, and for male urine samples, there was 100% positive agreement and 99.7% negative agreement for N. gonorrhoeae. For cervical swab samples, there was 98.8% positive agreement and 98.5% negative agreement for C. trachomatis, and there was 96.6% positive agreement and 99.8% negative agreement for N. gonorrhoeae. In limiting dilution analyses, we found that the Abbot assay was more sensitive than the Roche assay for both C. trachomatis and N. gonorrhoeae. In addition, there appeared to be an enhanced ability of the Abbott assay to detect dual infections, especially in the presence of large amounts of N. gonorrhoeae and small amounts of C. trachomatis organisms. In summary, we conclude that the Abbott RealTime CT/NG assay is an accurate and automated new addition to the available testing options for C. trachomatis and N. gonorrhoeae.The incidences of Chlamydia trachomatis and Neisseria gonorrhoeae infection continue to increase globally. A more intensive screening effort has been advocated by the U.S. Preventive Services Task Force (18), the Centers for Disease Control and Prevention (24), other public health agencies, and medical societies to bring this emerging epidemic under control. This includes the yearly screening of sexually active women under the age of 25 years for C. trachomatis. The goal of screening is to prevent transmission and the severe sequelae of unrecognized infection, such as pelvic inflammatory disease and associated infertility.Rapid, automated, and sensitive nucleic acid amplification testing methods are needed to respond optimally to this public health mandate. In this regard, there have been limited published evaluations of the recently FDA-cleared Abbott RealTime CT/NG assay (where "CT" stands for Chlamydia trachomatis and "NG" stands for Neisseria gonorrhoeae) (9). There was a recent report of clinical trial data comparing the Abbott assay to Gen-Probe Aptima Combo 2 (AC2), BD ProbeTec ET CT/GC, and GC culture (where "GC" represents N. gonorrhoeae) (6). There was also one prior study from Canada using a CE-marked Abbott kit with different cutoff and interpretation algorithms (8) and a U.S. study performed by Abbott Laboratories (Des Plaines, IL) using a prototype ...

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

“…Similarly, Rockett et al (15) showed that the cobas CT/NG assay for C. trachomatis detected 94.5% of the FVU specimens found to be positive by the firstgeneration Amplicor test. These studies (14,15) suggest that the two newer second-generation assays are performing comparably to the first-generation tests with FVU samples.…”

“…Cheng et al (14) compared the RealTime CT/NG assay and the first-generation Amplicor CT/NG assay, showing very high levels of agreement for FVU specimens. Similarly, Rockett et al (15) showed that the cobas CT/NG assay for C. trachomatis detected 94.5% of the FVU specimens found to be positive by the firstgeneration Amplicor test.…”

“…Endpoint-of-detection experiments in the earlier study (12) showed that the AC2 assay detected C. trachomatis to a dilution of 10 Ϫ8 or 1.0 to 0.1 elementary bodies (EBs) per 100 l, in contrast to the first-generation cobas Amplicor and ProbeTec ET tests, which detected 100 EBs per 100 l. The current study found the values to be 1 EB per 100 l for the AC2 assay and 10 to 100 EBs per 100 l for the cobas CT/NG, ProbeTec CT/GC Q x , and RealTime CT/NG assays. Cheng et al (14) showed that the RealTime CT/NG assay was 4 times more sensitive analytically than the firstgeneration cobas Amplicor test. These studies suggest that differences in analytical sensitivity may translate into differences in clinical sensitivity.…”

Performance of the cobas CT/NG Test Compared to the Aptima AC2 and Viper CTQ/GCQ Assays for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae

“…The CDC STD Laboratory Diagnosis Guidelines recommend screening using highly sensitive and specific nucleic acid amplification assays (NAATs) (4), confirming that this class of testing is now considered the standard for the diagnosis of these infections. NAATs have been commercially available for the last 2 decades, and evidence of their performance characteristics is widely available (6,7,(10)(11)(12)(13)(14)(15)(16)(17). As chlamydia and gonorrhea screening programs continue to expand to meet the health care coverage benchmarks described by the U.S. Preventive Task Force (USPTF), the CDC (5), and the Healthcare Effectiveness Data and Information Set (HEDIS), clinical diagnostic laboratories will experience increased volumes.…”

Swabs (dry or collected in universal transport medium) and semen can be used for the detection of Chlamydia trachomatis using the cobas 4800 system

“…Current screening for this bacterial STI pathogen among infertile men and semen donors is strongly recommended, as it can cause serious reproductive complications in the recipients of semen donations and infection in their offspring (Peeling & Embree, 2005;Eley & Pacey, 2011 cervical specimens are currently available with far higher sensitivity than cell culture or antigen detection (Semeniuk et al, 2002;Bébéar & de Barbeyrac, 2009). An increasing number of laboratories are now offering combinatorial NAATs for the diagnosis of both C. trachomatis and Neisseria gonorrhoeae infections (Gaydos et al, 2010;Hopkins et al, 2010;Rockett et al, 2010;Cheng et al, 2011;Kerndt et al, 2011). The Roche Diagnostics cobas CT/NG test, performed on the cobas 4800 system, is a new commercialized diagnostic assay using an automated workstation to isolate nucleic acids from clinical specimens and a real-time instrument for the detection of C. trachomatis and N. gonorrhoeae (Rockett et al, 2010;Taylor et al, 2012;Van Der Pol et al, 2012).…”