Determination of Chlamydia trachomatis Prevalence in an Asymptomatic Screening Population: Performances of the LCx and COBAS Amplicor Tests with Urine Specimens

Abstract

This study determined the performances of the LCx (Abbott) and COBAS Amplicor (Roche) tests with urine specimens for the detection ofChlamydia trachomatis in an asymptomatic screening population. Randomly selected women and men (age range, 15 to 40 years) registered in 20 general practices in Amsterdam, The Netherlands, were invited to participate in this study. Urine specimens (n = 2,906; 1,138 specimens from men and 1,717 specimens from women) were tested for C. trachomatis by the COBAS Amplicor (Roche) and LCx (Abbott) tests. Samples which were positive by only one assay were subjected to discrepant analyses by a third assay (in-house plasmid PCR). By the LCx assay C. trachomatis DNA was detected in urine specimens from 46 of 1,717 women and 29 of 1,138 men, while the COBAS Amplicor detected C. trachomatis DNA in 52 and 35 specimens, respectively. When comparing the LCx and COBAS Amplicor tests, 32 test results (20 for women and 12 for men) were discrepant. After discrepant analyses the following sensitivities, specificities, and positive predictive values were found for the LCx and COBAS Amplicor tests: 78.6 versus 98.8%, 99.7 versus 99.9%, and 88.0 versus 95.4%, respectively. No prominent differences were found between men and women with regard to the test performances. After discrepant analyses the overall prevalences ofC. trachomatis in women and men were 3.0 and 2.8%, respectively. For both women and men the prevalence in the younger age groups was higher than that in the older age groups. In conclusion, the COBAS Amplicor tests shows better diagnostic characteristics than the LCx assay for the detection of C. trachomatis in urine specimens from an asymptomatic screening population. In this asymptomatic population the overall prevalence of C. trachomatis was 2.9%.

Systematic Screening for Chlamydia trachomatis: Estimating Cost-Effectiveness Using Dynamic Modeling and Dutch Data

“…Screening programs have become more feasible with the introduction of sensitive DNA detection methods, such as the polymerase chain reaction (PCR) test on urine, and the highly effective single‐dose azithromycin treatment [6,7]. Active case finding and early treatment can prevent the development of sequelae and the transmission of the disease in the population.…”

Advances in diagnostic tests for bacterial STDs

“…The addition of 2% boric acid to the urine specimen may prevent the growth of bacteria during mailing and perhaps prevent the degradation of nucleic acid in the sample. 39 Morre et al 40 compared the performance of COBAS Amplicor with LCx using 2 906 mailed, first void urine specimens (1,138 from men and 1,717 from women) from an asymptomatic population (overall prevalence of C trachomatis was 2.9%). The IC results indicated that salud pública de méxico / vol.…”

Pooling of Urine Specimens for Detection of Asymptomatic Chlamydia trachomatis Infections by PCR in a Low-Prevalence Population: Cost-Saving Strategy for Epidemiological Studies and Screening Programs

“…However, while lowering the cutoff value in the LCR was necessary to identify all positive pools (1), the first study acknowledged the need to validate the pooling strategy using fresh urine specimens (7). Members of our group recently showed that PCR performs better than LCR for the detection of asymptomatic C. trachomatis infections in urine specimens from both males and females (5).…”

“…Specimen preparation and C. trachomatis testing were performed according to the instructions of the manufacturer and as described previously (5). For pooled urine specimens the same procedure for C. trachomatis detection was used except that, for pools of five urine specimens, instead of 0.5 ml of urine, five 100-l samples of urine, well mixed, were used (0.5 ml).…”