Phenotypic and Genotypic Characterization of Clinical Strains of CDC Group IVc-2

Abstract

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 andAlcaligenes 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 (16:1ω7c), cis-11-octadecanoic acid (18:1ω7c), and Δ-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 Δ-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 genusRalstonia, which includes R. eutropha, R. pickettii, and R. solanacearum.

CDC Group IV c-2: a New Ralstonia Species Close to Ralstonia eutropha

“…Despite the wide geographical range of their origins, all eight French clinical isolates and all four type strains obtained from the CDC had identical 16S rDNA sequences. In accordance with the results of Osterhout et al (17), our results show that the closest matches for C IV-2 all belong to the R. eutropha (formerly Alcaligenes eutropha) species. However, our phylogenetic analyses do not suggest a "close but distinct relationship" (17) but instead strongly favor the notion that C IV-2 belongs to the species R. eutropha.…”

“…All clinical isolates and type strains had identical 16S rDNA sequences (FRA01). Moreover, this sequence was identical to the recently published sequence AF067657 (17). When screening databases (GenBank and the Ribosomal Database Project), the closest matches were observed with R. eutropha strains.…”

“…We show here that the ID-32-GN identification system provides a simple, rapid, and reliable means of identifying C IV-2 with a high degree of confidence (99.9%). In contrast with previous studies, it dispenses with sophisticated complementary analyses, such as cellular fatty acid composition and 16S rRNA sequencing (17), and does not lead to the spurious identification of Bordetella bronchiseptica, Alcaligenes xylosoxidans, or Oligella ureolytica (3).…”

“…FRA01, sequence of clinical isolates and type strains. JHH, sequence obtained by Osterhout et al (17). Trees shown were obtained by neighbor joining.…”

“…At present, C IV-2 can be identified more or less reliably by biochemical identification procedures. Taxonomically, it was recently linked to the genus Ralstonia (17). In order to investigate the clonality of clinical isolates from different French hospitals and to assess similarity to Ralstonia eutropha strains we studied eight clinical isolates and four type strains by pulsed-field gel electrophoresis (PFGE), RAPD and 16S ribosomal DNA (rDNA) phylogenetic analysis, and biochemical characterization.…”