Cellular fatty acid composition of organisms frequently associated with human infections resulting from dog bites: Pasteurella multocida and groups of EF-4, IIj, M-5, and DF-2.

The cellular fatty acid composition of Pasteurella multocida and four unclassified groups of gram-negative bacteria (EF-4, M-5, IIj, and DF-2) which are frequently associated with human dog-bite infections was determined by gas-liquid chromatography. Strains of P. multocida were readily distinguished from the unclassified groups by the presence of 3-hydroxy myristic acid (3-OH- 14:0). Groups M-5 and EF-4 were characterized by the presence of 3-hydroxy lauric (3-OH-12:0) acid. Only group EF-4 organisms contained 2-OH-16:0, a-17:0, and 17:0 cyclopropane acids. Groups IIj and DF-2 differed from the other groups by the presence of large amounts of a branched-chain 15-carbon acid (i-15:0); they differed from each other by the presence of i-2-OH-15:0 and i-17:1 acids in IIj, which were absent in DF-2. The data indicate that gas-liquid chromatographic analysis for cellular fatty acids provides an additional test for rapid differentiation of these gram-negative organisms associated with dog-bite infections. Similarities observed in the fatty acid compositions of Flavobacterium, IIj, and DF-2 suggest that these two unclassified groups may be additional species of Flavobacterium.