Comparing Two Methods of Detection for Chlamydia trachomatis in Liquid-Based Papanicolaou Tests
ABSTRACT This study compared the performance of Chlamydia trachomatis testing using 2 methods: the BD ProbeTec Chlamydia trachomatis Q(x) Amplified DNA Assay (CTQ) on the BD Viper System with XTR technology (CTQ assay) and the Hybrid Capture (HC) 2 assay. A total of 1,054 Surepath and ThinPrep specimens were tested for C trachomatis nucleic acids using the CTQ assay and the HC2 assay. For positive and discrepant C trachomatis test results, confirmatory test for C trachomatis was performed using a reverse transcriptase-polymerase chain reaction. Of 1,054 liquid-based gynecologic cytology samples tested for C trachomatis using both assays, 1,041 tested negative on both. In 6 (0.57%) samples, findings were discordant. The CTQ assay and the HC2 assay had sensitivity rates of 100% and 66.7%, respectively, with comparable specificity (99.9%). The positive predictive values were 92.3% and 88.9% with the CTQ and HC2 assays, respectively. In this study, the CTQ assay was found to be more sensitive than the HC2 assay in detecting chlamydial infection; the CTQ assay also demonstrated a higher positive predictive value.
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ABSTRACT: The APTIMA COMBO 2 assay, which detects and amplifies rRNA from Chlamydia trachomatis and/or Neisseria gonorrhoeae, is approved for use on ThinPrep liquid-based Pap test specimens. The objective was to determine the clinical utility of the APTIMA assays (APTIMA COMBO 2 assay, APTIMA CT assay for Chlamydia trachomatis, and APTIMA GC assay for Neisseria gonorrhoeae) for screening women during their annual Pap exam, using SurePath liquid-based Pap test specimens. Two cervical samples were collected from 1,615 females attending six clinical sites in North America. A cervical broom sample was processed for cytology, with the residuum aliquoted into an APTIMA specimen transfer kit tube. The second cervical swab sample was put into APTIMA specimen transport medium, and both samples were tested with each APTIMA assay on a direct sampling system. Using a subject-infected status that utilized cervical-swab specimen results from two APTIMA assays, the prevalence was 7.9% for Chlamydia trachomatis and 2.5% for N. gonorrhoeae. For the liquid-based Pap samples, the sensitivities, specificities, positive predictive values, and negative predictive values for Chlamydia trachomatis detection were 85.2%, 99.5%, 93.2%, and 98.7%, respectively, for the APTIMA COMBO 2 assay and 89.1%, 98.7%, 85.7%, and 99.1%, respectively, for the APTIMA CT assay. For N. gonorrhoeae detection, the values were 92.5%, 100%, 100%, and 99.8%, respectively, for the APTIMA COMBO 2 assay and 92.5%, 99.9%, 97.4%, and 99.8%, respectively, for the APTIMA GC assay. The high predictive values support the use of the assays with SurePath liquid-based Pap specimens processed with the APTIMA specimen transfer kit.Journal of Clinical Microbiology 09/2007; 45(8):2434-8. DOI:10.1128/JCM.00013-07
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ABSTRACT: Digene's Hybrid Capture 2 (HC2) CT/GC, CT-ID, and GC-ID DNA tests were evaluated by comparison to traditional culture methods for detecting Chlamydia trachomatis and Neisseria gonorrhoeae infections in 669 cervical specimens from high-risk female populations attending two sexually transmitted disease clinics. For detection of either or both infections, the HC2 CT/GC test algorithm had 93.8% sensitivity and 95.9% specificity compared to those of culture. After resolution of discrepant results by direct fluorescent-antibody (DFA) staining or PCR assay, the relative sensitivity and specificity of the HC2 CT/GC test algorithm increased to 94.8 and 99.8%, while the values for culture were 83.6% (McNemar's P value, 0.0062) and 100%, respectively. For detection of the individual pathogens, the relative sensitivities for the HC2 CT-ID and GC-ID tests were 97.2 and 92.2% and the specificities were greater than 99% compared to culture adjucated by DFA staining and PCR. Test performance varied at the two clinics: the HC2 CT/GC algorithm, CT-ID, and GC-ID tests had significantly higher sensitivities (McNemar's P value, <0.05) than that of culture for the population at one clinic as well as for the combined populations. At the other clinic, the HC2 tests performed as well as culture.Journal of Clinical Microbiology 02/2002; 40(2):641-4. DOI:10.1128/JCM.40.02.641-644.2002
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ABSTRACT: The Digene Hybrid Capture II (HC II) CT/GC Test (Digene Corp., Beltsville, MD) is a new nucleic acid signal amplification-based test for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in specimens from the genital tract. For optimal results, the HC II CT/GC Test employs a special conical shaped brush for cervical specimen collection from nonpregnant women and swabs from pregnant women. To validate a protocol for HC II C. trachomatis and N. gonorrhoeae testing of specimens collected for the GenProbe PACE 2 System. Specimens were collected from 1,746 patients with a swab and placed in GenProbe transport media according to the manufacturer's recommended procedure. The specimens were first tested at two clinical laboratories by the PACE 2 system, and then blindly tested by HC II CT/GC using an adjusted cutoff value. Discrepant specimens were adjudicated by polymerase chain reaction (PCR), and the result common to two of the three testing methods (HC II, PACE 2, and PCR) was defined as the consensus result. Combining the data from both sites, the relative sensitivity of the HC II Test compared with the consensus result for the detection of 1,761 specimens for C. trachomatis and 1,750 specimens for N. gonorrhoeae was 100% for both organisms. The relative specificities for C. trachomatis and N. gonorrhoeae detection were 99.8% and 99.7%, respectively. The relative sensitivities of the PACE 2 CT and GC Systems were 86.5% and 87.1%, respectively, with relative specificities of 99.9% and 100%. The difference in sensitivity between HC II and PACE 2 for C. trachomatis detection was significant (P < 0.016). The HC II CT/GC Test can be performed using specimens collected in GenProbe transport media and has a significantly greater sensitivity for C. trachomatis detection than the PACE 2 System.Sex Transm Dis 05/1999; 26(5):303-8. DOI:10.1097/00007435-199905000-00012