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Smith KR, Fisher HC III, Hook, EW III: Prevalence of fluorescent monoclonal antibody-nonreactive Neisseria gonorrhoeae in five North American sexually transmitted disease clinics.J Clin Microbiol 34:1551-1552, 1996We compared a direct fluorescent monoclonal antibody (DFA) test with alternative enzymatic and fermention 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 the DFA confirmatory reagent and reactive by both the Quad-Ferm and Rapid NH tests. The prevalence of DFA-nonreactive Neisseria gonorrhoeae isolates varies geographically and is independent of local methods for the identification of possible gonococci.On the basis of our findings, we recommend that for use in medicolegal and other instances in which a diagnosis of gonorrhea has the potential to have far-reaching effects, it is appropriate to test DFA reagent-nonreactive, oxidase-positive, gram-negative diplococci by alternative methods of gonococcal confirmation.Although the prevalence of such isolates could change, the fluorescent monoclonal antibody confirmation reagents remain useful for many clinical situations. Their ease of use and ready applicability for screening large numbers of isolates make them useful for many laboratories.

Gram negative cocci which occur in pairs with their adjacent sides flattened, giving them a coffee bean appearance, are typical of the genus Neisseria. Neisseria gonorrhea is commonly found within white blood cells; these organisms must be carefully sought within genital tract specimens, and their presence or absence should be specifically noted in the report.The presence of intracellular gram negative diplococci in a purulent male urethral smear is presumptive evidence of gonococci, but this assumption cannot be made in a female.Beware of other organisms which resemble gonococci but are found extracellularly, such as Acinetobacter lwoffi, which must be distinguished biochemically.Direct smears read specifically for the presence of gonococci should include a direct reference to gram negative intracellular diplococci.