Characterization of “Brachyspira hampsonii” clades I and II isolated from commercial swine in Western Canada

Abstract

A novel Brachyspira emerged in 2009 and has since become a production-limiting pathogen of pigs in North America. The name “ Brachyspira hampsonii” has been proposed for this novel taxon. “ Brachyspira hampsonii” is divided into two phylogenetically distinct clades based on the sequence of the NADH-oxidase ( nox) gene, although the clinical disease associated with clades I and II is indistinguishable and phenotypic characteristics that discriminate the clades have not been determined. The objectives of the current study were to enhance the description of the provisional species “ B. hampsonii” with biochemical profiles and morphometric data from isolates affecting Canadian swine and to investigate potentially diagnostically informative characteristics for this emerging pathogen. Biochemical profiles of isolates from different commercial swine barns in Western Canada showed that biochemical profiles were insufficient to distinguish “ B. hampsonii” clades I and II from each other or from other pathogenic Brachyspira. Hippurate hydrolysis, previously reported as uniformly negative in “ B. hampsonii,” was variable among Canadian isolates. Spirochete dimensions and flagella numbers for “ B. hampsonii” overlapped with other Brachyspira species. Taken together, these results indicate that nox gene sequencing remains a preferred method for identification and discrimination of “ B. hampsonii” from other pig-associated Brachyspira spp.