STUDIES ON THE KLEBSIELLA-AEROBACTER GROUP OF BACTERIA

Abstract

Studies of 756 cultures of the Klebsiella-Aerobacter group are summarized. The cultures were divided into 128 motile and 638 nonmotile strains. No satisfactory method yet has been found to distinguish between Aerobacter aerogenes and members of the genus Klebsiella and for the present they should be considered as a single group. No single biochemical test or combination of tests sufficed clearly to distinguish the genus Klebsiella and A. aerogenes from cultures of Aerobacter cloacae, and many aberrant and intermediate strains occurred. The classification of the group was considered and motility and gelatin liquefaction were found most satisfactory in separation. It was suggested that the monmotile forms which do not liquefy gelatin, heretofore classified in both genera, Klebsiella and Aerobacter. be placed in the former genus and that the latter genus be redefined as a motile, liquefying group with A. cloacae as the type. The 629 nonmotile, capsulated cultures which were included in the study were subjected to capsular typing and the distribution of the capsular types isolated from various sources was given. The practicability and significance of capsule typing were discussed.