Identification of clinical isolates of Neisseria gonorrhoeae by a coagglutination test.

Ninety-eight per cent of laboratory isolates of Neisseria gonorrhoeae from a veneral disease clinic gave positive reactions with a gonococcal coagglutination test. The prototype reagent, however, was poor at distinguishing between different species of the genus Neisseria: 75% of strains of Neisseria meningitidis and 40% of other Neisseria species tested gave positive reactions. None of the origanisms other than Neisseria growing on the diagnostic cultures from the clinic gave positive reactions. We therefore suggest that the present reagent is unsuitable for testing isolates from the upper respiratory tract. The technique is simple, rapid, and convenient and with a more specific antibody could be useful. Results of coagglutination reactions of 126 strains of Neisseria grown on serum-containing and serum-free media were very similar and there is no need to use special serum-free media.