Comparison of the performance of the BD ProbeTec SDA assay for Chlamydia trachomatis with the Roche Cobas PCR assay using female urine and vulvo-vaginal swab specimens

• Published in: International journal of STD & AIDS 2004-05, Vol.15, p.7
• Main Authors: Paul, I, Sell, J, Eastick, K, Longhurst, D
• Format: Article
• Language: English
• Subjects: Chlamydia trachomatis
• ISSN: 0956-4624; 1758-1052

To compare the performance of the Becton Dickinson ProbeTec ET strand displacement amplification assay (SDA) for Chlamydia trachomatis with the well-established Roche Cobas PCR assay using first-passed urine (FPU) and vulvo-vaginal swab (VVS) specimens from women.Comparison of 1171 VVS and 493 FPU specimens from women participating in a wider trial of diagnostic methods was undertaken. Patients received diagnosis using 3 separate specimen types and at least 3 separate assays. This allowed us to use patient infection status as our comparator for assay performance. Of the 1179 VVS specimens, 153(13%) were true positives and of the 493 FPU specimens, 53 (10.6%) were true positives. The BD ProbeTec ET SDA performed well, with VVS specimens giving equivalent sensitivity to PCR (94.6% vs 93.3%, respectively) with less inhibition. However, with urine specimens the assay was less sensitive than that of PCR (62% vs 79%), in agreement with other emerging evidence that the analytical sensitivity of SDA may be less than that of PCR. Specificity was good with both platforms and both specimen types (>99.5%). Both assays detected more positive patients using VVS specimens. A larger performance assessment of the ProbeTec ET SDA for C. trachomatis is essential before the widespread adoption of this assay by laboratories undertaking chlamydia screening using female urine specimens. VVS specimens have advantages if they are acceptable to the participants undergoing screening.