Slide agglutination technique for the rapid differentiation of Mima polymorpha and Herellea from the Neisseriae.

The genera Mima and Herellea, members of the tribe Mimeae (De Bord, 1942), contain organisms which morphologically resemble the Neisseriae upon primary isolation. Since they are being isolated in increasing numbers from the spinal fluid of patients with acute meningitis, a method for their differentiation from the Neisseriae would be advantageous. Schaub and Hauber (1948) classified a gramnegative rod, of which the diplococcal forms predominated on solid media, as Bacterium anitratum, or B5W. B. anitratum has also been isolated from cases of meningitis. Ewing (1949) stated that on the basis of morphological characteristics and physiological reactions, B. anitratum should be classified in the tribe Mimeae. Hence, we have also included in our studies the 10 capsular serotypes of B. anitratum designated by Ferguson and Roberts (1950). Stuart et al. (1949) found that heated cells of B. anitratum were inagglutinable. Ferguson and Roberts (1950) observed, in serological studies with a limited number out of 109 strains of B. anitratum, that of several antigens prepared from a single strain and heated at 121 C for up to 3 hr, some agglutinated with the homologous antiserum while others remained inagglutinable. We have also made this observation with strains of Mima polymorpha and Herellea sp. collected here. In addition, we have found that living suspensions of these organisms are inagglutinable in homologous antisera. In a previous publication, typing of M. polymorpha by a precipitin technique has been reported (Cary et al., 1956). The precipitating antigen described therein behaved as a specific serotype rather than reacting as a group factor with all Mimeae antisera. For this reason, we initiated experiments to determine whether a common group antigen was present and, if so, whether its detection would facilitate rapid differentiation of strains of M. polymorpha from the Neisseriae. In this laboratory, various physical and chemical agents were used to treat strains of M. polymorpha and Herellea sp. in order to obtain a suspension of organisms which could be used in serological procedures. These included treatment with acid, alkali, formamide, and pangestin, a mixture of pancreatic enzymes. Of the methods tried, it was found that by treatment of cells with alkali the presence of a group antigen for M. polymorpha and one for Herellea sp. could be demonstrated.