Evaluation of COBAS AMPLICOR (Roche): Accuracy in Detection of
            <i>Chlamydia trachomatis</i>
            and
            <i>Neisseria gonorrhoeae</i>
            by Coamplification of Endocervical Specimens

Livengood, Charles H.; Wrenn, Jane W.

doi:10.1128/jcm.39.8.2928-2932.2001

Cited by 41 publications

(23 citation statements)

References 12 publications

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“…Previous studies have reported similar specificities, with corresponding PPVs of more than 80% (4,10,13,14). Although these specificities are high, there is controversy in the literature with respect to the methods used to calculate them, particularly in regards to the use of discrepant analysis (7,8).…”

Section: Discussionsupporting

confidence: 53%

“…Studies on the utility of this test in diagnosing infection with N. gonorrhoeae have demonstrated sensitivities ranging from 92.4 to 100% for endocervical or urethral swabs and from 42.3 to 94.1% for urine specimens, while specificity has been high (95.9 to 99.9%) for all specimens (4,5,10,13,14,(20)(21)(22). The majority of these studies were performed in populations with a high prevalence (4.4 to 20.1%) of infection, resulting in positive predictive values (PPV) greater than 80%.…”

mentioning

confidence: 99%

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Confirmation by 16S rRNA PCR of the COBAS AMPLICOR CT/NG Test for Diagnosis of Neisseria gonorrhoeae Infection in a Low-Prevalence Population

2002

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The COBAS AMPLICOR CT/NG test is widely used for the diagnosis of Neisseria gonorrhoeae infection using genital swabs or urine samples. Although highly specific, cross-reactivity occurs with some nonpathogenic strains of Neisseria and Lactobacillus species. In low-prevalence populations, even highly specific assays may require confirmatory testing of positive results. We assessed the positive predictive value (PPV) of this test in a low-prevalence (0.5%) setting. Genital and urine specimens testing positive using the COBAS AMPLICOR NG test were retested using an investigational 16S rRNA PCR assay. Additionally, 737 specimens were tested in parallel by both culture and the above PCR protocol. Of 9,772 specimens tested in-house, 168 were positive by the AMPLICOR test; in addition, 62 AMPLICOR-positive specimens were referred to our laboratory for confirmatory testing, yielding 230 positive specimens. Of these, 72 were confirmed positive by 16S rRNA PCR, yielding a specificity of 98.7% and a PPV of 31.3%. Specificity was similar for all specimen types, whereas PPV varied with prevalence: specimens from males, females, urine specimens, and genital swabs had PPVs of 70.8, 13.3, 51.9, and 20.1%, respectively. The PPV was higher when the initial AMPLICOR optical density (OD) was >3.5 versus initial and repeat OD readings in an equivocal zone of >0.2 to <3.5 (65.1 versus 10.1%; P < 0.001). On repeat testing of specimens with ODs in the equivocal zone, 54 gave ODs of >0.2 and <2.0, 35 gave ODs of >2.0 and <3.5, and 12 gave ODs of >3.5, with 3.7, 20, and 33.3% confirmed positive, respectively (P ‫؍‬ 0.004). Comparing PCR to culture as the "gold standard," specificity increased from 96.8 to 99.9% when 16S rRNA PCR was performed on specimens positive by the COBAS AMPLICOR NG test. Confirmatory testing with a more specific method such as 16S rRNA PCR should be considered in low-prevalence populations, especially for specimens with an OD in the equivocal zone.Neisseria gonorrhoeae remains the second most prevalent sexually transmitted bacterial infection after Chlamydia trachomatis, with approximately 650,000 new infections occurring annually in the United States (2). A significant proportion of these infections, especially in women, are asymptomatic and, if they remain undiscovered, may result in such long-term consequences as pelvic inflammatory disease, chronic pelvic pain, ectopic pregnancy, and infertility (9). Furthermore, silent and untreated infection facilitates the spread of this organism to unsuspecting sexual partners. Therefore, accurate diagnosis of both symptomatic and asymptomatic infection is critical.A number of techniques have been developed to detect genital infections caused by N. gonorrhoeae. The current "gold standard" for diagnosis of infection is by culturing endocervical or urethral swab specimens on selective media. However, even under optimal laboratory conditions, the sensitivity of gonococcal cultures ranges from 85 to 95% for acute infection (17) and falls to approximately 50% for females with c...

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Section: Discussionsupporting

confidence: 53%

mentioning

confidence: 99%

Confirmation by 16S rRNA PCR of the COBAS AMPLICOR CT/NG Test for Diagnosis of Neisseria gonorrhoeae Infection in a Low-Prevalence Population

2002

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“…The specificity measured by using the interpretation defined for this study resulted in PCR specificities of 99.3 and 99.0% for C. trachomatis and N. gonorrhoeae, respectively. These values are well within the range reported for this assay (12,18,22,29,30).…”

Section: Discussionsupporting

confidence: 75%

“…Although these assays have demonstrated excellent sensitivities and specificities in clinical trials (6,28,29,30), they require extreme technical precision in order to achieve maximum performance (18,22,28). With the assays available at present, this translates into labor-intensive diagnostic methods, often with low-throughput capacity (2,3,16).…”

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confidence: 99%

Evaluation of the Digene Hybrid Capture II Assay with the Rapid Capture System for Detection ofChlamydia trachomatisandNeisseria gonorrhoeae

et al. 2002

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Screening for chlamydial and gonococcal infection has been strongly recommended for all sexually active women under the age of 26. Advances in the ability to detect infection by nucleic acid detection techniques have improved access to screening methods in routine clinical practices. To meet the increasing demand for testing, a high-throughput system is desirable. We evaluated the performance of the Hybrid Capture 2 CT/GC (HC2) assay with the Digene Rapid Capture System (HC2-RCS). The results of HC2-RCS for endocervical samples from 330 women were compared to those of culture and the COBAS Amplicor PCR. For detection of chlamydial infection, HC2-RCS had a sensitivity and a specificity similar to those of PCR (P > 0.5) and an improved sensitivity compared to that of culture (P ‫؍‬ 0.007). For identification of gonococcal infections, all assays performed similarly (P > 0.5). The performance of HC2-RCS was also compared to that of the manual HC2 format (HC2-M) with these samples and with 911 endocervical samples collected previously. The performance of HC2-RCS was equivalent to that of HC2-M; the overall concordance rates for the detection of chlamydia and gonorrhea were 99.7% ( ‫؍‬ 0.97) and 99.8% ( ‫؍‬ 0.97), respectively. When the HC2 assay was performed with a semiautomated system application designed for high throughput, it demonstrated high sensitivity and a high specificity for detection of both Chlamydia trachomatis and Neisseria gonorrhoeae.

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“…Along with the rapid generation of results, C. trachomatis-specific (20,25,32) and N. gonorrhoeaespecific (20,22,25) nucleic acid hybridization assays provide analytical sensitivities equivalent to that of culture. The commercial availability of nucleic acid amplification tests (NAATs) has greatly enhanced the detection of both of these agents (1,7,11,15,29,30) in genital swab specimens submitted to clinical laboratories.…”

mentioning

confidence: 99%

Evaluation of Gen-Probe APTIMA-Based Neisseria gonorrhoeae and Chlamydia trachomatis Confirmatory Testing in a Metropolitan Setting of High Disease Prevalence

et al. 2007

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Prompted by reports challenging the validity of the low-positive Neisseria gonorrhoeae and Chlamydia trachomatis results generated by the APTIMA Combo 2 assay (Gen-Probe, Incorporated) and by a Centers for Disease Control and Prevention recommendation to confirm N. gonorrhoeae-or C. trachomatis-positive screens by using an alternative amplification target, we report on a comparison of this means of confirmation with an in-house algorithm of repeat testing. Primary clinical specimens yielding N. gonorrhoeaeor C. trachomatis-specific luminescent values between 100,000 and 1,000,000 were repeat tested in duplicate. A subset of specimens was forwarded for confirmatory assays (Gen-Probe) individualized for alternative N. gonorrhoeae or C. trachomatis targets. An 18-month audit revealed that 230 of 29,977 C. trachomatis screens (0.8%) and 41 of 29,064 N. gonorrhoeae assays (0.1%) yielded low-positive data. When a subset of 40 low-positive N. gonorrhoeae screens was repeat tested, 20 (50.0%) remained positive; 22 (55.0%) of the screens remained positive following performance of the confirmatory assay. In contrast, repeat testing of 153 low-positive C. trachomatis screens yielded a positive result for fewer specimens (n ‫؍‬ 97; 63.4%) than when commercial confirmatory testing was used (n ‫؍‬ 124; 81.0%). However, confirmation of the results for additional C. trachomatis screens by use of an alternative target did not translate into significant differences in the calculated overall C. trachomatis-positive screen rates (7.39% by repeat testing versus 7.52% by the confirmatory assay; P ‫؍‬ 0.53). Furthermore, use of the confirmatory assay raised the positive predictive value only 1.8% over that of repeat testing. Molecular confirmatory testing did not significantly enhance the reliability of C. trachomatis-or N. gonorrhoeae-specific nucleic acid amplification testing in this metropolitan setting compared to the reliability of repeat testing.

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Evaluation of COBAS AMPLICOR (Roche): Accuracy in Detection of Chlamydia trachomatis and Neisseria gonorrhoeae by Coamplification of Endocervical Specimens

Cited by 41 publications

References 12 publications

Confirmation by 16S rRNA PCR of the COBAS AMPLICOR CT/NG Test for Diagnosis of Neisseria gonorrhoeae Infection in a Low-Prevalence Population

Confirmation by 16S rRNA PCR of the COBAS AMPLICOR CT/NG Test for Diagnosis of Neisseria gonorrhoeae Infection in a Low-Prevalence Population

Evaluation of the Digene Hybrid Capture II Assay with the Rapid Capture System for Detection ofChlamydia trachomatisandNeisseria gonorrhoeae

Evaluation of Gen-Probe APTIMA-Based Neisseria gonorrhoeae and Chlamydia trachomatis Confirmatory Testing in a Metropolitan Setting of High Disease Prevalence

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