Comparison of biochemical, morphologic, and chemical characteristics of Centers for Disease Control fermentative coryneform groups 1, 2, and A-4.

A total of 24 strains of fermentative coryneform like bacteria isolated from clinical specimens form two distinct groups which have been designated Centers for Disease Control (CDC) fermentative coryneform groups 1 (13 strains) and 2 (11 strains). The phenotypic characteristics of group 1 were similar to those of a previously described CDC group designated A-4, with the major differentiating characteristic being the inability to hydrolyze esculin. Major differences in cellular fatty acid composition between CDC groups 1 and A-4 were also observed. The branched-chain fatty acids 14-methylhexadecanoate and 12-methyltetradecanoate, which account for more than 80% of the total acids of group A-4, were not detected in cells of group 1 strains. Groups 1 and 2, which have similar cellular fatty acid compositions, can be differentiated on the basis of fermentation of xylose, mannitol, lactose, sucrose, and melibiose by group 1 but not by group 2. The sources of isolation of the strains of both groups varied. Only group 1 strains were associated with eye infections.