EVALUATION OF THE VIDAS CHLAMYDIA TEST TO DETECT AND VERIFY CHLAMYDIA-TRACHOMATIS IN UROGENITAL SPECIMENS

The Vidas Chlamydia test (CHL) is an automated enzyme-linked immunoflu orescence assay for the detection of Chlamydia trachomatis. Positive a nd equivocal results are confined with a blocking assay, A mouse monoc lonal antibody directed against the chlamydial lipopolysaccharides via s used for the test, Thee CHL assay is widely used in Europe, but U.S. experience with it is limited. Three clinical test sites (The Arlingt on Hospital, Arlington, Va., Indiana University, Indianapolis, and the University of California, San Francisco) compared CHL with tissue cul ture (TC) for the identification of chlamydia in urogenital specimens (2,453 females and 850 males), True positives (TP) were defined as eit her TC positive or TC negative and CHL positive by a positive direct f luorescent-antibody assay or PCR test. Overall prevalence was 5.5% for females, 10.3% for male urethral swabs, and 10.7% for combined male T C urethral swabs and CHL with first catch urine (FCU) specimens, Compa red to TP, CHL and TC had sensitivities of 89.6 and 94.1% with female cervical, swabs and 90.9 and 86.4% with male urethral swabs, respectiv ely, CHL sensitivity was 81.2 for male FCU specimens and 77.7% for mat ching male TC swabs. There were relatively few false-positive results, with all specificities being >99.4%, With the blocking assay, Vidas C HL specificity was >99.7%. However, male FCU specimen sensitivity was compromised because 9.2% (7 of 76) of the TP were initially positive b ut were not confirmed, An improvement in the Vidas blocking assay is n eeded before we can recommend its use with male urine, Alternatively, one could argue that the specificity of the Lest is so high that a con firmatory assay is not needed,For male and female swabs, the Vidas CHL assay has a performance that is similar to that of TC.