Multicenter clinical trial and laboratory utilization of an enzymatic detection method for gonococcal antigens

Seven institutions participated in a comparative study evaluating standard culture method and a new enzyme immunoassay (EIA, Gonozyme, Abbott Diagnostics) for the detection of Neisseria gonorrhoeae. Five hundred twenty-three patients were entered from hospitals of various sizes representing different population densities, ethnic and economic sectors, and gonococcal prevalence. Statistical analysis showed sensitivity, specificity, and positive and negative predictive values of 80.3%, 94.6%, 66.2%, and 97.3% for the total population tested. For the high-prevalence (greater than 15%) population the respective values were as follows: 78.6%, 91.5%, 68.8%, and 94.7%. Specimens from females had a lower sensitivity than those from males. In the low-prevalence population (less than 10%) results were as follows: 100%, 97.8%, 50%, and 100%. A cost comparison emphasized the benefit of the Gram's stain and culture. It also indicated that, unless batched or assayed at high volume, Gonozyme is not cost competitive for laboratories using standard culture methods. The impact of the EIA method, in general, and Gonozyme, specifically, on the microbiology section also was investigated. Integration would require altering of established work patterns and loss of flexibility and freedom of standard plating technics. The fact that Gonozyme is a "presumptive" test limits it to being a complementary assay, not an alternative. The authors conclude that Gonozyme is optimally suited to a high-volume laboratory, screening a low-prevalence female outpatient population, where specimen transport is a problem and gonococcal resistance to penicillin has not been demonstrated. This would include sexually transmitted disease clinics, reference laboratories, and state health departments.