Identification of gonococcal cultures by means of their cytoplasmic antigens and an anti-cytoplasm antiserum.

Soluble antigens were released by sonication from the cells of 60 primary cultures of Neiserria gonorrhoeae, 7 other species of neisseriae and 26 "mixed" cultures containing colonies of N. gonorrhoeae and other bacteria. Rabbits were injected with the soluble antigens of four strains of gonococci (clonal types 1 and 2), four other species of neisseriae and ten bacterial genera other than Neisseria. The antigens were tested against the non-absorbed antisera by a counter-immunoelectrophoresis method. It was found that the antiserum produced against the antigens of one N. gonorrhoeae strain, the strain GEK, reacted exclusively with the sonicates of all N. gonorrhoea cultures whether pure or mixed with other microorganisms. In contrast, the antisera to the antigens of all other N. gonorrhoeae strains cross-reacted with antigens of N. catarrhalis or N. sicca. Thus, the unique restricted reactivity of the anti-GEK antiserum permits its utilization as an immunological reagent for prompt identification of gonococcal cultures.