Comparison of three commercially available amplification assays, AMP CT, LCx, and COBAS AMPLICOR, for detection of Chlamydia trachomatis in first-void urine

Abstract

We compared the Gen-Probe transcription-mediated amplification assay (AMP CT), the Abbott LCx assay, and the Roche COBAS AMPLICOR assay for the detection of Chlamydia trachomatis in a mixed population in urine samples. First-void urine, urethral specimens, and cervical specimens in females were obtained from 1,000 patients (544 males and 456 females) visiting the outpatient sexually transmitted disease clinic of our hospital. The prevalence of C. trachomatis infection was 7.7% as determined by tissue culture of urethral and cervical specimens. The sensitivities of LCx, COBAS AMPLICOR, and AMP CT compared to cell culture were 79, 86, and 78%, respectively. Sensitivity and specificity were recalculated by using a new "gold standard", i.e., a sample was considered to be true positive if two or more techniques yielded positive results. Specimens positive only by cell culture or positive in only one commercial amplification technique were retested by a previously described in-house PCR. After discordance analysis the sensitivities of LCx, COBAS AMPLICOR, and AMP CT were 84, 93, and 85%, respectively. Specificity exceeded 99% for all three assays. With each method the sensitivity was lower for urine samples from females compared to urine samples from males. By application of this new gold standard, existing differences between methods are highlighted; future evaluations of new techniques should be validated against two or more amplification assays.

Use of Ligase Chain Reaction with Urine versus Cervical Culture for Detection of Chlamydia trachomatis in an Asymptomatic Military Population of Pregnant and Nonpregnant Females Attending Papanicolaou Smear Clinics

“…Additionally, the experiment which tested the archived urine of 65 pregnant women demonstrated only three (4.6%) inhibited specimens. This value is of the same order of magnitude as that reported by others for inhibition in urine specimens (2.6 and 1.8%) for amplified testing (3,15). Most investigators now believe that inhibitors to amplification exist for both urine and cervical specimens (3,15,35).…”

“…This value is of the same order of magnitude as that reported by others for inhibition in urine specimens (2.6 and 1.8%) for amplified testing (3,15). Most investigators now believe that inhibitors to amplification exist for both urine and cervical specimens (3,15,35). A combination of heat treatment (95°C for 10 min) and 10-fold dilution of the processed specimen reduced inhibition of PCR from 19 to 4% in one study (35).…”

“…Approximately half (55.2%) were 25 years or younger, and 50.8% were African-American. Over 90% were enlisted personnel, 98.3% reported vaginal sex, 11.3% had a new sex partner in the previous 90 days, 15.2% had more than one sex partner in the previous 90 days, 88.5% reported inconsistent condom use, and 30.8% were pregnant (Table 1). Reasons for clinic visit, clinical presentation, and sexual risk history are presented in Table 1.…”

First evaluation of six nucleic acid amplification tests widely used in the diagnosis of Chlamydia trachomatis in Russia

“…These findings are, in general, consistent with previous reports. [32][33][34][35] Nevertheless, using the reference methods, none of the samples was inhibited. This is probably due to the fact that MagNA Pure LC was used for automated DNA isolation, which has previously been shown to increase the sensitivity and significantly lower the rate of inhibition.…”

Molecular genetic methods for diagnosis and characterisation of Chlamydia trachomatis and Neisseria gonorrhoeae: impact on epidemiological surveillance and interventions

“…The Gen‐Probe APTIMA TM assay (Gen‐Probe) for C. trachomatis uses transcription‐mediated amplification (TMA) to detect a specific 23S rRNA target, which is present in hundreds of copies in each Chlamydia organism. The Gen‐Probe TMA assay was included in a comparison with LCR and COBAS Amplicor assays for detection of C. trachomatis in first‐void urine (22); the results were evaluated versus cell culture, and no significant differences were demonstrated between the three commercial techniques. But when using a new “gold standard”, i.e.…”