Campylobacter californiensis sp. nov. isolated from cattle and feral swine

Authors: Miller, William - Bill; Chapman, Mary; Williams, Tina; Wood, Delilah - De; Bono, James - Jim; KELLY, DAVID - University Of Sheffield

Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Strains of the species Campylobacter are commonly associated with human illness. Campylobacter jejuni is considered the leading cause of bacterial human gastroenteritis worldwide. In addition to C. jejuni, other Campylobacter species have also been linked with disease in both humans and livestock. Nine Campylobacter strains were recovered from the feces of cattle and feral swine in California. Three were recovered from a Campylobacter-associated dairy outbreak, although these strains were not linked epidemiologically to any human illness. The other six strains were recovered during a later survey of California farms and ranches. Metabolic and genomic analyses indicated that these nine strains represent a novel Campylobacter species, for which the name Campylobacter californiensis is proposed. Although not linked to the dairy outbreak, these strains contain a toxin-encoding genomic island that could potentially result in human illness. Further work will be necessary to determine the virulence potential of this organism.

Technical Abstract: Nine Campylobacter strains were isolated from cattle and feral swine feces: three were recovered during a 2007 Campylobacter-associated dairy outbreak and the other six were isolated during a 2009-2010 survey of farms and ranches in Central California. The species identification of these strains could not be determined by 16S rRNA gene sequencing but were most similar to Campylobacter concisus and Campylobacter mucosalis. Additional atpA typing indicated that the nine strains composed a discrete novel clade related to C. concisus and C. mucosalis. A polyphasic study was undertaken here to clarify their taxonomic position. Phylogenetic analyses were performed based on 16S rRNA gene sequences and the concatenated sequences of 330 core genes. The core gene analysis placed the nine strains into a clade well separated from the other Campylobacter taxa, indicating that these strains represent a novel Campylobacter species. Pairwise digital DNA-DNA hybridization and average nucleotide identity values were lower than 16% and 73%, respectively, further supporting their placement into a novel taxon. Standard phenotypic testing was performed. All strains are microaerobic, anaerobic, motile, Gram-negative, spiral cells that are oxidase positive but catalase negative. Strains can be distinguished from the other catalase-negative Campylobacter species using phenotypic markers such as motility, oxidase activity, cephalothin resistance, hippuricase activity, growth at 30 °C, and a-hemolysis. The data presented here show that these strains represent a novel species within Campylobacter, for which the name Campylobacter californiensis sp. nov. (type strain =RM6914T, =LMG 32304T, =CCUG 75329T) is proposed.