Campylobacter cuniculorum sp. nov., from rabbits

Eight strains of an unknown thermotolerant Campylobacter species were isolated from the caecal contents of rabbits (Oryctolagus cuniculus). All strains were initially identified as belonging to the genus Campylobacter by means of genus-specific PCR, but none were identified using species-specific PCR for known thermophilic species. Cells were spiral shaped with bipolar unsheathed flagella, with no periplasmic fibres, and appeared coccoid after 10-12 days of incubation. Phylogenetic analyses based on 16S rRNA gene, rpoB and groEL sequences revealed that all strains formed a robust clade that was very distinct from recognized Campylobacter species. 16S rRNA gene sequence pairwise comparisons of strain 150B(T) with the type strains of other Campylobacter species revealed that the nearest phylogenetic neighbour was Campylobacter helveticus NCTC 12470(T), with 96.6 % similarity. The uniqueness of these rabbit isolates was confirmed by whole-cell protein electrophoresis. Taken together, these data indicate that the strains belong to a novel Campylobacter species for which the name Campylobacter cuniculorum sp. nov. is proposed, with 150B(T) (=LMG 24588(T) =CCUG 56289(T)) as the type strain.