Comparing urine samples and cervical swabs for Chlamydia testing in a female population by means of Strand Displacement Assay (SDA)

Abstract

BackgroundThere has been an increasing number of diagnosed cases of Chlamydia trachomatis in many countries, in particular among young people. The present study was based on a growing request to examine urine as a supplementary or primary specimen in screening for Chlamydia trachomatis in women, with the Becton Dickinson ProbeTec (BDPT) Strand Displacement Assay (SDA). Urine samples may be particularly important in screening young people who are asymptomatic.MethodsA total of 603 women aged 15 and older were enrolled from the Sexually Transmitted Infection (STI) clinic at Haukeland University Hospital, Norway, in 2007. Only 31 women were older than 35 years. Cervical swabs and urine samples were tested with BDPT for all participants. In cases of discrepant test results from a given patient, both samples were retested by Cobas TaqManCT and a Polymerase Chain Reaction (PCR)-method (in-house). Prevalence of C. trachomatis, sensitivity, and specificity were estimated by latent class analysis using all test results available. Bootstrap BC confidence intervals (10 000 computations) were estimated for sensitivity and specificity, and their differences in cervix vs. urine tests.ResultsA total of 1809 specimens were collected from 603 patients. 80 women (13.4%) were positive for C. trachomatis. Among these, BDPT identified 72 and 73 as positive in cervix and urine samples, respectively. Of the 523 C. trachomatis negative women, BDPT identified 519 as negative based on cervical swabs, and 514 based on urine samples. Sensitivity for cervical swabs and urine samples with the BDPT were 89.0% (95% CI 78.8, 98.6) and 90.2% (95% CI 78.1, 95.5), respectively. The corresponding values for specificity were 99.2% (95% CI 98.3, 100) and 98.3% (95% CI 96.4, 100).ConclusionsThis study indicates that urine specimens are adequate for screening high-risk groups for C. trachomatis by the SDA method (BDPT). Such an approach may facilitate early detection and treatment of the target groups for screening, and be cost-effective for patients and the health services.

Chlamydia trachomatis, Mycoplasma genitalium and Ureaplasma urealyticum among students in northern Norway

“…For detection of C. trachomatis DNA, an accredited (NS‐EN ISO/IEC 17 025) in‐house qPCR was used which amplifies and detect a 112 bp region of the truncated inclusion membrane protein A ( incA ) gene in C. trachomatis The method features a 252 bp Internal Amplification Control (IAC) 27 with primer recognition sites for the C. trachomatis primers and an internal sequence from the pGEM ® ‐luc plasmid (Promega, Maddison, WI, USA), which is recognized by the internal amplification control probe (IAC‐P) 21 …”

Diagnostic relevance of simultaneous testing for Chlamydia trachomatis and Neisseria gonorrhoeae

“…To the best of our knowledge, samples were taken under precautions to avoid commensal contamination from our instructed physicians committed to good pre-analytical practices [9]; the use of swabs versus smears could not be retrospectively determined.…”

“…It is now well recognised that studies which evaluate the prevalence of a given infectious condition are based on different analytical procedures, such as epidemiological surveys, questionnaires, laboratory analyses and clinical status [6,8,9]. We were interested to see whether ordering physicians asking selectively for CT and NG or both were right or wrong in their suspicions.…”

Screening for chlamydia

“…2,4,5 Previous studies have shown that more women will choose to be screened if it is an easy and noninvasive method, making urine screening the screening test of choice. There are two main ways to screen for chlamydia: cervical swabs or urine tests.…”