Differentiation of Neisseriaceae by Isoenzyme Electrophoresis

Analysis of 71 strains of Neisseriaceae by starch-gel electrophoresis of hexokinase, phosphoglucomutase, glucose phosphate isomerase, and l-malate-nicotinamide adenine dinucleotide phosphate oxidoreductase showed that all gonococci and all meningococci have a characteristic hexokinase isoenzyme that is specific for each species and clearly distinguishes meningococci and gonococci from each other and from other species of Neisseriaceae. Strains of gonococci that were transformed into maltose utilizers by DNA from Neisseria lactamica and Neisseria meningitidis showed no change in the isoenzymes so that they could still be differentiated from meningococci and other Neisseriaceae by isoenzyme electrophoresis. In view of the limited sensitivity and specificity of conventional tests for the identification of gonococci and the possibility that gonococci may be transformed into maltose utilizers by DNA from normal throat flora, electrophoresis of hexokinase isoenzymes should be useful for the precise laboratory identification of the pathogenic neisseriae, especially those from atypical sites and those giving indeterminate reactions.