Prevalence of fluorescent monoclonal antibody-nonreactive Neisseria gonorrhoeae in five North American sexually transmitted disease clinics.

We compared a direct fluorescent monoclonal antibody (DFA) test with alternative enzymatic and fermentation tests for identifying presumptive gonococcal isolates in a systematic sample from patients attending five sexually transmitted disease clinics in five cities. Fourteen (2.5%) of 556 isolates from three clinics were nonreactive with DFA confirmatory reagent and reactive by both the Quad-Ferm (BioMerieux Vitek Inc.) and the Rapid NH (Innovative Diagnostic Systems, Inc.) tests. The prevalence of DFA-nonreactive Neisseria gonorrhoeae isolates varies geographically and is independent of local methods for the identification of possible gonococci.