Phenotypic and genotypic characterization of clinical strains of CDC group IVc-2.

CDC group IVc-2 is a gram-negative, oxidase-positive, nonfermentative bacillus that has been implicated in human infections, including septicemia and peritonitis. Biochemically it most closely resembles Bordetella bronchiseptica and Alcaligenes sp. Results of cellular fatty acid (CFA) and 16S rRNA gene analysis were combined with biochemical data to assist in identification and classification. The predominant CFAs were hexadecanoic acid (16:0), cis-9-hexadecanoic acid (16:1omega7c), cis-11-octadecanoic acid (18:1omega7c), and Delta-cis-9,10-methylenehexadecanoic acid (17:0cyc). Small amounts (2 to 5%) of 3-hydroxytetradecanoic acid (3-OH-14:0), tetradecanoic acid (14:0), 2-hydroxyhexadecanoic acid (2-OH-16:0), and Delta-cis-11,12-methyleneoctadecanoic acid (19:0cyc) were also consistently present. The highest 16S rRNA gene similarity was with Ralstonia eutropha and Ralstonia solanacearum. The CFA and 16S rRNA gene sequence data support the inclusion of CDC group IVc-2 in the recently created genus Ralstonia, which includes R. eutropha, R. pickettii, and R. solanacearum.