Phenotypic and molecular characterization of a novel strongly hemolytic Brachyspira species, provisionally designated “Brachyspira hampsonii”

Abstract

Abstract. Since 2007, outbreaks of severe bloody diarrhea and hemorrhagic colitis have been reported in the United States and Canada. Though the primary causative agent of swine dysentery is Brachyspira hyodysenteriae, which is strongly hemolytic, the current report describes the isolation of a novel strongly hemolytic Brachyspira sp. This novel Brachyspira sp. was identified from clinical submissions at the Minnesota Veterinary Diagnostic Laboratory, and 40 of such isolates were obtained from 22 clinical submissions representing 5 states. Isolates were confirmed to be different from any known Brachyspira sp. on the basis of phylogenetic analysis of nucleotide sequences of nox and 16S ribosomal RNA (rRNA) genes. Phylogenetic analyses grouped all isolates into 2 clades (clades I and II), and grouping patterns were similar for both nox and 16S rRNA gene sequence analyses. Phenotypically, all isolates were indole and hippurate negative, and enzymatic profiling indicated 2 types of profiles, irrespective of the phylogenetic grouping, differing only in the production of β-glucosidase. The results suggest that a potentially virulent new species of Brachyspira sp., provisionally named "Brachyspira hampsonii ", is circulating among swine herds in the United States.

Identification of weakly haemolytic Brachyspira isolates recovered from pigs with diarrhoea in Spain and Portugal and comparison with results from other countries

“…The three strongly haemolytic species Brachyspira hyodysenteriae, "Brachyspira suanatina" (Råsbäck et al, 2007a) and "Brachyspira hampsonii" (Chander et al, 2012) are porcine pathogens, causing colitis, whilst the weakly haemolytic species vary in their pathogenic potential. Brachyspira pilosicoli is a pathogen, being the agent of porcine intestinal spirochaetosis (Trott et al, 1996), Brachyspira murdochii has been associated with mild colitis and diarrhoea (Weissenböck et al, 2005;Komarek et al, 2009;Jensen et al, 2010;Hammer and Gebhart, 2013), Brachyspira intermedia is of uncertain clinical significance in pigs, and Brachyspira innocens generally has been considered to be non-pathogenic (Hampson, 2012).…”

“…Consequently other identification methods have been developed based on the sequence of conserved genes, notably those encoding 16S rRNA, 23S rRNA and NADH oxidase (nox). Analysis of nox sequences has emerged as a robust method for identification of Brachyspiraspecies as the gene is relatively conserved but also shows speciesspecific variation (Atyeo et al, 1999;Burrough et al, 2012;Chander et al, 2012;Rubin et al, 2013). A more discriminatory multilocus sequence typing (MLST) scheme analyzing the sequence of seven genes encoding "housekeeping" enzymes has been described for identification and typing of Brachyspira isolates (Råsbäck et al, 2007b), but it is laborious and has not been widely used apart from analysis of B. hyodysenteriae (La et al, 2009;Osorio et al, 2012) and other indole-positive species (Phillips et al, 2010).…”

Minimum inhibitory concentration of Brazilian Brachyspira hyodysenteriae strains

“…Since 2007, an increasing number of cases of swine dysentery have been described, mainly in the United States of America and Canada (Clothier et al 2011, Chander et al 2012. In Brazil, between 2010 and 2014, the Veterinary Pathology Laboratory of the Universidade Federal de Minas Gerais (UFMG) diagnosed 18 new swine dysentery outbreaks, which raised concern due to the previous history of only sporadic cases with a low economic impact.…”

“…A total of 30 different isolates, preferably from different herds, were selected for nox gene amplification to identify species belonging to genus Brachyspira and subsequent genomic sequencing, according to Chander et al (2012). The following primers were used (primer): Brachy nox F 5'-GTT CTT GCG CTG TAA CTC CTC CTA T-3') and Brachy nox R (5'-GCA ACA ATA CCC ATT CTT ACA G -3'), both of which are nox -specific and target a highly variable region of the gene (Atyeo et al 1999).…”

“…B. suanatina and B. hampsonii (clades I and II) have also been described as causative agents of swine dysentery (Rasback et al 2007, Chander et al 2012), but only B. hyodysenteriae has been described in Brazil. Swine dysentery causes severe mucohaemorrhagic diarrhoea with high morbidity and mortality in untreated animals (Taylor & Alexander 1971).…”