Cellular fatty acid (CFA) compositions of 561 asporogenous, aerobic gram-positive rods were analyzed by gas-liquid chromatography as an adjunct to their identification when grown on blood agar at 35°C. The organisms could be divided into two groups. In the first group (branched-chain type), which included coryneform CDC groups A-3, A-4, and A-5; some strains of B-1 and B-3; "Corynebacterium aquaticum"; Brevibacterium liquefaciens; Rothia dentocariosa; and Listeria spp., the rods had sizable quantities of anteisopentadecanoic (Ca.1s) and anteisoheptadecanoic (Cal7:0) acids. Other species with these types of CFA included B. acetylicum, which contained large amounts of isotridecanoic (Ci13:0) and anteisotridecanoic (Cal3:0) acids. CFAs useful for distinguishing among Jonesia denitrificans, Oerskovia spp., some strains of CDC groups B-1 and B-3, Kurthia spp., and Propionibacterium avidum were hexadecanoic (C 16:0) acid, isopentadecanoic (Cil5:0) acid, and Ca15:0. The second group (straight-chained type), which included Actinomyces pyogenes;

Seventy strains of fermentative, asporogenous, gram-positive coccobacilli or short rods form two closely related groups which have been designated CDC fermentative coryneform groups 3 (32 strains, xylose fermenters) and 5 (38 strains, xylose nonfermenters). The two taxa are otherwise similar to each other phenotypically and culturally and by a distinctive Staphylococcus-like odor and by cellular fatty acid (CFA) composition. CDC group 3 and CDC group 5 strains have been isolated from clinical sources (blood, abscesses, and wounds but not urine or respiratory specimens) in Canada and the United States and among referrals from Belgium, Sweden, and Spain. Coryneform CDC group 3 strains were phenotypically similar to CDC coryneform group A-3 but were distinguishable by their inability to reduce nitrate and by their lack of motility. Coryneform CDC group 5 isolates were phenotypically somewhat similar to Actinomyces viscosus and Rothia dentocariosa, except that none of this group reduced nitrate. Both CDC groups could be differentiated from these similar bacteria by the ability to decarboxylate lysine and ornithine. The CFA compositions of CDC group