Roseomonas, a new genus associated with bacteremia and other human infections

Abstract

In the 1980s, a pink bacterium different from species of the genus Methylobacterium was implicated in human infection. Using biochemical tests and DNA hybridization, we examined 42 strains of pink-pigmented, gram-negative bacteria that were not members of the genus Methylobacterium. The isolates included 6 strains each of CDC "pink coccoid" groups I, II, III, and IV; 10 isolates from Gilardi's "unnamed taxon"; and 8 blood isolates from ill, debilitated, or immunosuppressed patients. The DNA hybridization studies supported the creation of six genomospecies encompassing the 42 strains. Reactions for esculin hydrolysis, glycerol oxidation, and D-mannose oxidation enabled separation of genomospecies 1 through 4. These tests, as well as motility, nitrate reduction, citrate utilization, and oxidation of L-arabinose, D-galactose, and D-xylose, differentiated genomospecies 5 and 6 from each other and from genomospecies 1 through 4. These organisms were susceptible in vitro to the aminoglycosides, tetracycline, and imipenem and generally susceptible to the quinolones. We propose the new genus, Roseomonas, for these bacteria to include three named species, Roseomonas gilardii sp. nov., Roseomonas cervicalis sp. nov., and Roseomonas fauriae sp. nov., and three unnamed genomospecies.

Acinetobacter , Chryseobacterium , Moraxella , and Other Nonfermentative Gram-Negative Rods

“…The former Roseomonas genomospecies 3 (Roseomonas fauriae) and genomospecies 6 have been transferred to the genus Azospirillum (Rhodospirillaceae, Alphaproteobacteria), a genus of nitrogen-fixing plant symbionts that is in a different order of bacteria (43,82). Some strains of this genus may occasionally be isolated from clinical material (179).…”

“…Colonies of Methylobacterium species are small, dry, and coral pink. Under UV light, Methylobacterium colonies appear dark due to absorption of UV light (179). Growth is fastidious on ordinary media such as TSA, producing 1-mm-diameter colonies after 4 to 5 days on SBA, modified Thayer-Martin, buffered charcoal-yeast extract, and Middlebrook 7H11 agars, with the best growth occurring on Sabouraud agar and usually no growth on MacConkey agar.…”

“…The original description of the genus Roseomonas (Acetobacteraceae, Alphaproteobacteria) included three named species, R. gilardii (genomospecies 1), R. cervicalis (genomospecies 2), and R. fauriae (genomospecies 3), and three unnamed species, Roseomonas genomospecies 4, 5, and 6 (179). Roseomonas genomospecies 3 and 6 have been transferred to the genus Azospirillum.…”

Catheter-related bacteremia due to Roseomonas gilardii sp. nov

“…Roseomonas gilardii sp. nov. is a pink-pigmented, oxidative, gram-negative coccobacillus that is infrequently isolated from clinical samples and whose pathogenic role remains unclear (1,2).…”

“…nov., and R. fauriae sp. nov., and three unnamed genomospecies (1,3). Even though isolation of Roseomonas spp.…”