Taxonomic characterisation of ceftazidime-resistant Brevundimonas isolates and description of Brevundimonas faecalis sp. nov.

Three ceftazidime-resistant strains isolated from the sewage water of a municipal hospital in Palma de Mallorca, Spain, were analysed phenotypically and genotypically to clarify their taxonomic positions. Sequence determinations and phylogenetic analyses of the 16S rRNA genes indicated that strains CS20.3(T), CS39 and CS41 were affiliated with the species of the alphaproteobacterial genus Brevundimonas, most closely related to B. bullata, B. diminuta, B. naejangsanensis and B. terrae. Additional sequences analyses of the ITS1 region of the rRNA operon and the genes for the housekeeping enzymes DNA gyrase β-subunit and RNA polymerase β-subunit, genomic DNA-DNA hybridisation similarities, cell fatty acid profiles and physiological and biochemical characterizations supported the recognition of CS20.3(T) (CCUG 58127(T)=CECT 7729(T)) as a distinct and novel species, for which the name Brevundimonas faecalis sp. nov. is proposed. Strains CS39 and CS41 were ascribed to the species B. diminuta.