Brachyspira

Brachyspira
Scientific classification
Kingdom:	Bacteria
Phylum:	Spirochaetes
Class:	Spirochaetes
Order:	Brachyspirales
Family:	Brachyspiraceae
Genus:	Brachyspira Hovind-Hougen et al. 1983
Species
Brachyspira aalborgi Hovind-Hougen et al. 1983 emend. Ochiai, Adachi & Mori 1998 non Foliella non Pfeiffer 1855 Brachyspira alvinipulli Stanton et al. 1998 Brachyspira canis ♠ (Duhamel et al. 1998) Oxberry & Hamspon 2003 Brachyspira corvi ♠ Jansson et al. 2008 Brachyspira hampsonii ♠ Chander et al. 2012 Brachyspira hyodysenteriae (Harris et al. 1972) Ochiai et al. 1998 Brachyspira ibaraki ♠ (presumably an 16S-rDNA variant of B. aalborgi) ♠ Tachibana et al. 2003 Brachyspira innocens (Kinyon and Harris 1979) Ochiai et al. 1998 Brachyspira intermedia (Stanton et al. 1997) Hampson and La 2006 Brachyspira murdochii (Stanton et al. 1997) Hampson and La 2006 Brachyspira pilosicoli (Trott et al. 1996) Ochiai et al. 1998 Brachyspira muridarum ♠ Backhans et al. 2010 Brachyspira muris ♠ Backhans et al. 2010 Brachyspira pulli ♠ Stephens and Hampson 2001 Brachyspira rattus ♠ Backhans et al. 2010 Brachyspira suanatina ♠ Rasback et al. 2007
Synonyms
Serpula Stanton et al. 1991 non (Persson 1801) Gray 1821 non Linnaeus 1758 Serpulina Stanton 1992 non Zborzevski 1834

Brachyspira is a genus of bacteria classified within the phylum Spirochaetes.

Brachyspira species include known pathogens in animals, mostly pigs but also birds, dogs, and humans while some species like B. innocens or B. intermedia are considered harmless commensals in animals.

B. hyodysenteriae and B. pilosicoli are the classic Brachyspira gastrointestinal pathogens leading to diarrheal disease in growing pigs worldwide, causing the so-called swine dysentery, typhlocolitis or porcine intestinal spirochaetosis, which contributes to major "production losses" in agrobusiness.

B. intermedia and B. pilosicoli can cause disease in poultry.

B. pilosicoli can infect humans leading to human intestinal spirochaetosis, however most cases of HIS are caused by B. aalborgi, so its clinical relevance remains unclear.

In the U.S.A. Brachyspira-associated pig disease and isolation of Brachyspira species from swine with diarrheal disease largely disappeared from swine herds in the late 1990s and early 2000s, but returned in the mid-2000s for unknown reasons.

A 2011 study of isolates from Midwestern swine herds described major changes in Brachyspira spp frequency and hemolysis, i.e. pathogenicity: the majority of isolated Brachyspira species were previously considered minimally pathogenic or commensal, like Brachyspira murdochi (27%)or novel/unclassifiable Brachyspira species (25%), while only 40.5% of 79 isolates from diseased pigs could be confirmed as the classic pathogens B. hyodysenteriae or Brachyspira pilosicoli by PCR. Brachyspira species previously capable of weak hemolysis only, like B. intermedia and B. pilosicoli were found to produce strong hemolysis. They were also frequently identified from diseased swine which suggests they are emerging pathogens.

A compelling explanation for this change in epidemiology and ecology is selection by the increasing use of antibiotics in pigs (e.g. as growth promoters), since B. murdochii and unclassifiable Brachyspira spp. are less susceptible to antimicrobials than the previously established Brachyspira pathogens.

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