A novel enteropathogenic, strongly haemolytic spirochaete isolated from pig and mallard, provisionally designated ‘Brachyspira suanatina’ sp. nov.

Abstract

Atypical, strongly haemolytic porcine isolates of intestinal spirochaetes differing genetically from Brachyspira hyodysenteriae were identified and characterized. The isolates were subjected to culture and biochemical tests, antimicrobial susceptibility testing and molecular analyses. None of four species-specific polymerase chain reaction systems targeting genes of B. hyodysenteriae gave a positive reaction. All the atypical porcine isolates were identical in their partial 16S rRNA and nox gene sequences with a previously described isolate from a mallard (Anas platyrhynchos), and differed only slightly from another mallard isolate. All these isolates were distinctly different from all currently recognized Brachyspira species. A challenge study was carried out using recently weaned pigs. Clinical signs and macroscopic changes consistent with swine dysentery were seen both in pigs given the atypical porcine isolate and in control pigs given the reference strain of B. hyodysenteriae (B204(R)). Pigs given the genetically similar isolate from a mallard became colonized and diarrhoea was observed. This is the first study indicating that Brachyspira isolates from mallard can infect pigs and induce diarrhoea. We propose that this atypical spirochaete genotype should be regarded as a new species within the genus Brachyspira, and be provisionally designated 'Brachyspira suanatina' sp. nov.

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

“…is challenging. 17 Although PCR methods are useful for differentiation of B. hyodysenteriae and B. pilosicoli, PCR assays have been shown to have low sensitivities in detecting Brachyspira directly from clinical samples, 11 and perhaps more importantly, such assays are unable to identify many clinically relevant Brachyspira isolates to the species level.…”

“…but very similar to isolates derived from mallards. 17 These isolates were recovered from pigs with swine dysentery and, in a challenge study, appeared to produce clinical signs and macroscopic changes consistent with the disease. 17 The findings suggest that several unrecognized Brachyspira species play an important role in clinically relevant swine intestinal disease.…”

“…17 These isolates were recovered from pigs with swine dysentery and, in a challenge study, appeared to produce clinical signs and macroscopic changes consistent with the disease. 17 The findings suggest that several unrecognized Brachyspira species play an important role in clinically relevant swine intestinal disease. However, some species appear to be less of a clinical concern, and other potentially clinically relevant species and/or strains may still require appropriate taxonomic classification and/or recognition.…”

Multiple-Locus Variable-Number Tandem-Repeat Analysis of the Swine Dysentery Pathogen, Brachyspira hyodysenteriae

“…Moreover, B. hyodysenteriae survives in the environment for long periods, especially in liquid feces contained in pits and lagoons, where it may remain infective for up to 60 days (16). This spirochete also can naturally colonize mice, rheas, chickens, and mallards (9,30), and together with mechanical vectors or fomites, this increases the ways in which B. hyodysenteriae may be spread within and between herds.…”

Minimum inhibitory concentration of Brazilian Brachyspira hyodysenteriae strains

“…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).…”