Comparison of an enzyme immunoassay (IDEIA) with tissue culture isolation for detection of Chlamydia trachomatis using a single swab.

We directly compared a monoclonal antibody-based enzyme immunoassay (IDEIA) with isolation of Chlamydia trachomatis in cell culture (Buffalo Green Monkey cells) by changing the transport medium used for the IDEIA test so as to allow use of a single swab for both tests of the two techniques. We also modified the IDEIA test to exclude any possibility of false positive results caused by non-specific interference by Staphylococcus aureus. The observed sensitivity of the IDEIA compared to cell culture was rather low, 80.3% (57/71). However the IDEIA test's specificity was excellent, 99.7% (566/564) giving a positive predictive value of 96.6% and a negative predictive value of 97.9% (isolation rate by cell culture = 11%).