Brachyspira hyodysenteriae and other strongly  -haemolytic and indole-positive spirochaetes isolated from mallards (Anas platyrhynchos)

Abstract

The aims of the current study were to collect intestinal spirochaetes (genus Brachyspira) from farmed and wild mallards (Anas platyrhynchos) and to identify and classify those isolates that phenotypically resembled Brachyspira hyodysenteriae, an enteric pathogen of pigs. The isolation rate of Brachyspira spp. was high from both farmed (93 %) and wild mallards (78 %). In wild mallards, it appeared that Brachyspira spp. were more likely to be found in migratory birds (multivariate analysis: RR 1 . 8, 95 % CI 1 . 1-3 . 1) than in mallards sampled in a public park. Pure cultures of putative B. hyodysenteriae were obtained from 22 birds. All five isolates from farmed mallards and ten randomly selected isolates with this phenotype were used for further studies. All isolates from farmed mallards and two of the isolates from wild mallards were PCR-positive for the tlyA gene of B. hyodysenteriae. Two isolates from farmed mallards were selected for pulsed field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD) analysis. These isolates clustered with the type and reference strains of B. hyodysenteriae. 16S rDNA sequence analysis performed on 11 of the strains showed that they were all closely related to each other and to the B. hyodysenteriae-Brachyspira intermedia cluster. Three of the mallard isolates had 16S rDNA sequences that were identical to those of B. hyodysenteriae strains R1 and NIV-1 previously isolated from common rheas (Rhea americana). To conclude, the isolates from farmed mallards and two isolates from wild mallards were classified as B. hyodysenteriae based on the fact that they could not be differentiated by any of the applied methods from type, reference and field strains of B. hyodysenteriae. The remaining isolates could not be assigned irrefutably to any of the presently recognized Brachyspira species. These results point to a broader host spectrum of B. hyodysenteriae than is generally recognized, and to the presence in mallards of strongly â-haemolytic and indole-producing spirochaetes that possess many, but not all, of the currently recognized characteristics of B. hyodysenteriae.

Detection of Brachyspira hyodysenteriae, Lawsonia intracellularis and Brachyspira pilosicoli in feral pigs

“…The only wildlife species so far that has been identified as being naturally colonized with B. hyodysenteriae are feral mallards, and to date this has only been demonstrated in Scandinavia ( Jansson et al, 2004). It is possible that the feral pigs may have come into contact with water sources contaminated with faeces from feral mallards that were carrying the spirochaete, or there may be other animal or environmental reservoirs of this pathogen.…”

Identification of Brachyspira hyodysenteriae and Other Pathogenic Brachyspira Species in Chickens from Laying Flocks with Diarrhea or Reduced Production or Both

“…This spirochete also naturally infects and causes typhlocolitis in rheas (Rhea americana) (19,31). More recently, strongly ␤-hemolytic B. hyodysenteriae was isolated from mallards in Sweden (17). There has been a brief unconfirmed report mentioning the isolation of B. hyodysenteriae from Dutch commercial poultry (45) and a very recent brief report of it being isolated from laying chickens in the United Kingdom (42).…”

Development of a multilocus sequence typing scheme for intestinal spirochaetes within the genus Brachyspira

“…Furthermore, MLEE is often not sufficiently discriminatory at the strain level for use in detailed molecular epidemiological studies on Brachyspira species. More discriminatory techniques that have been used include pulsed-field gel electrophoresis (PFGE) (Atyeo et al, 1996(Atyeo et al, , 1999a and random amplified polymorphic DNA (RAPD) analysis (Dugourd et al, 1996;Jansson et al, 2004). It should be acknowledged, however, that sometimes the results obtained by these techniques can be difficult to interpret or reproduce or both (Maiden et al, 1998), and improved methods are needed.…”

“…'Brachyspira canis' (Duhamel et al, 1998), 'Brachyspira pulli' (Stephens & Hampson, 2001) and 'Brachyspira suanatina ' (Råsbäck et al, 2007) are provisionally designated species; the last causes a disease in pigs similar to swine dysentery. Additionally, isolates exist that cannot be classified into presently recognized Brachyspira species because of atypical phenotypic or genotypic features or both (Atyeo et al, 1999b;Thomson et al, 2001;Jansson et al, 2004).…”