Starch-fermenting, gelatin liquefying corynebacteria and their differentiation from C. diphtheria gravis.

During recent years attention has been drawn to the isolation of starch-fermenting, gelatin-liquefying corynebacteria from acute cases of sore throat (Jebb, 1948; Saxholm, 1951). Fourteen strains have been isolated in this laboratory between January, 1946, and June, 1951, 12 from acute tonsillar infection, one from the throat of a symptomless carrier, and one from a lesion on the hand. In addition, a further 31 strains from other laboratories have been investigated by one of us (W. H. H. J.). With the decrease in the number of cases of gravis diphtheria these 14 strains formed a considerable proportion (35%) of all starch-fermenting corynebacteria isolated in this laboratory during the last five years (Table I). The strains can be distinguished from C. diphtheriae both biochemically and because they produce two toxins, only