Evaluation of Clearview and Magic Lite tests, polymerase chain reaction, and cell culture for detection of Chlamydia trachomatis in urogenital specimens

Abstract

The Clearview Chlamydia test (CV; Unipath Ltd., Bedford, United Kingdom), the Magic Lite Chlamydia test (ML; CIBA Corning, Medfield, Mass.), a polymerase chain reaction (PCR), and cell culture (CC) were evaluated for detection of Chlamydia trachomatis in urogenital specimens. Specimens were collected from 283 men and 724 women visiting the outpatient clinic for Sexually Transmitted Diseases at the University Hospital Rotterdam, Rotterdam, The Netherlands. ML, PCR, and CC were all performed on the same sample to prevent swab-to-swab variability. CV was performed on a separate sample. Analysis of discordant results was performed by application of the following confirmatory assays: first, PCR on the CC, second, ML was repeated, and third, PCR was repeated by using a different DNA extraction protocol. If more than one test was positive, the sample was considered true positive. If only one test was positive, which was confirmed by the confirmatory assay, the sample was also considered true positive. By using these interpretations, the following results were obtained. The sensitivity and specificity of CV for samples from men were 60.4 and 86.3%, respectively. For samples from women, these values were 62.3 and 99.7%, respectively. The low specificity for samples from men was caused by unidentified substances in the swab that was used. The use of CV on samples from men is not recommended by the manufacturer. For samples from women, the specificity of CV was high, but the low sensitivity of CV limits its use for diagnostic purposes. The sensitivities of ML were low for samples from both men and women (68.8% and 50.9% respectively), while specificities were excellent for samples from both groups (100 and 99.9%, respectively). The low sensitivity of ML limits its diagnostic value. The PCR technique was highly specific for samples from both men (99.6%) and women (99.9%). The sensitivity of PCR, however, was unexpectedly low for samples from both groups (men, 87.5%; women, 79.2%), most likely because of the sample treatment method used. The sensitivity and specificity values of CC for samples from men were 95.8 and 100%, respectively. For samples from women, these values were 100 and 99.9%, respectively. In the present study, CC was the most reliable technique for the detection of C. trachomatis.