Evaluation of the relatedness of Brucella spp. and Ochrobactrum anthropi and description of Ochrobactrum intermedium sp. nov., a new species with a closer relationship to Brucella spp.

Abstract

Evaluation of the relatedness ofThe relatedness of Brucella spp. and Ochrobactrum anthropi was studied by protein profiling, Western blot, immunoelectrophoresis and 16s rRNA analysis. Whole-cell and soluble proteins of brucellae and 0. anthropi showed serological cross-reactivities quantitatively and qualitatively more intense than those existing with similar extracts of Agrobacterium spp. Numerical analysis of Western blot profiles of whole-cell extracts showed that 0. anthropi LMG 3301 was closer to Brucella spp. than to 0. anthropi LMG 3331T, a result not obtained by protein profiling. These differences were not observed by Western blot with soluble fractions, and immunoelectrophoretic analyses suggested that this was due to destruction of conformational epitopes in Western blot procedures with the subsequent simplification of antigenic profile. Analysis of the 165 rRNA sequences of strains previously used in the species definition confirmed that strain LMG 3301, and also LMG 3306, were closer to the brucellae, and that LMG 3331T was in a separate cluster. The LMG 3301 and the LMG 3331T clusters could also be separated by their different colistin sensitivity and by PCR with 16s rRNA Brucella primers, and both methods showed strains of both clusters among clinical isolates classified as 0. anthropi by conventional tests. These results and those of previous DNA-DNA hybridization studies [Holmes, B. , Popoff, M., Kiredjian, M. & Kersters, K. (1988). Int J Syst Bacterial 38,4064161 show that the LMG 3301 cluster and related clinical isolates should be given a new species status for which the name Ochrobactrum intermedium sp. nov. is proposed (type strain is LMG 3301T = NCTC 12171' = CNS 2-75').

Molecular and phenotypic features for identification of the opportunistic pathogens Ochrobactrum spp.

“…All these discrepancies suggested that O. intermedium possessed a faint urease activity as previously underlined by Lebuhn et al (2000). This could explain the discrepancy observed between the urease activity results reported for O. intermedium in previous studies (Lebuhn et al, 2000;Moller et al, 1999;Velasco et al, 1998). Urease activity should no longer be considered as a criterion for genus identification, but rather as a biochemical characteristic useful for the discrimination of the two Ochrobactrum species of medical interest, O. anthropi and O. intermedium.…”

“…On the basis of phenotypic characteristics, the genus Ochrobactrum could be related to the genera Alcaligenes, Achromobacter, or to the members of Pseudomonadaceae. However, molecular taxonomy places Ochrobactrum in the AE-subgroup of proteobacteria, closely related to the genus Brucella (Lebuhn et al, 2000;Velasco et al, 1998). Surprisingly, 16S rDNA-based phylogeny, as well as protein profiling (Velasco et al, 1998) and AFLP analysis (Leal-Klevezas et al, 2005), place O. intermedium strains closer to Brucella spp.…”

“…Since this description, five other species, Ochrobactrum intermedium (Velasco et al, 1998), Ochrobactrum tritici, Ochrobactrum grignonense (Lebuhn et al, 2000), Ochrobactrum gallinifaecis (Kämpfer et al, 2003) and 'Ochrobactrum lupini' (Trujillo et al, 2005) have been characterized, mainly on the basis of 16S rDNA sequencing. They are non-fermentative, strictly aerobic, motile, oxidase-positive and indole-negative, Gramnegative rods.…”

Ochrobactrum haematophilum sp. nov. and Ochrobactrum pseudogrignonense sp. nov., isolated from human clinical specimens

“…The genus Ochrobactrum was introduced by Holmes et al (1988) and, at the time of writing, the genus comprises the nine species Ochrobactrum anthropi (Holmes et al, 1988), O. intermedium (Velasco et al, 1998), O. tritici and O. grignonense (Lebuhn et al, 2000), O. gallinifaecis (Kämpfer et al, 2003b), O. lupini (Trujillo et al, 2005), O. oryzae (Tripathi et al, 2006), O. pseudintermedium (ZurdoPiñeiro et al, 2007) and O. cytisi (Teyssier et al, 2007).…”

Specific detection and differentiation of Ochrobactrum anthropi, Ochrobactrum intermedium and Brucella spp. by a multi-primer PCR that targets the recA gene

“…Ochrobactrum and Brucella are genetically closely related genera of the family Brucellaceae within the class Alphaproteobacteria (Velasco et al, 1998), with Ochrobactrum intermedium, the closest relative to Brucella, sharing 98.8 % rRNA gene similarity with Brucella spp.…”