Characterization and Recognition of Brachyspira hampsonii sp. nov., a Novel Intestinal Spirochete That Is Pathogenic to Pigs

Abstract

T he genus Brachyspira includes Gram-negative aerotolerant anaerobic spirochetes that colonize the intestine of and/or cause disease in a wide range of host species (1). Over several decades, multiple taxonomic changes were applied to members of this genus (originally Treponema, which was then transferred to Serpula, to Serpulina, and finally to Brachyspira) (2-5). Currently, the genus Brachyspira consists of eight valid species, B. hyodysenteriae, B. pilosicoli, B. intermedia, B. innocens, B. murdochii, B. aalborgi, B. alvinipulli, and most recently, B. suanatina (1, 6). This genus also consists of several provisional species (1), of which the most clinically significant is the recently discovered "Brachyspira hampsonii" (7). Within the Brachyspira genus, all currently identified strongly beta-hemolytic species (B. hyodysenteriae, B. suanatina, and the novel B. hampsonii) are known to cause severe mucohemorrhagic diarrhea in pigs, while weakly beta-hemolytic Brachyspira species are either commensals (B. innocens) or are capable of causing diarrhea and/or colitis (B. pilosicoli, B. murdochii, B. intermedia, B. aalborgi, and B. alvinipulli) in pigs, chickens and/or humans (1). B. hyodysenteriae, the most virulent and clinically significant Brachyspira species, has historically also been the most researched or investigated species. It causes swine dysentery (SD), a disease characterized by mucohemorrhagic diarrhea that is most commonly observed in grower-finisher pigs (1). In addition to the adverse impact on the health and welfare of pigs, its negative effect on productivity (such as decreased weight gain and poor feed conversion) leads to significant economic losses to livestock-raising communities and countries (1). The recently validated B. suanatina also causes SD in pigs; however, its isolation has been limited to a few northern European countries (8). The isolation of different bacterial species from clinically and pathologically indistinguishable dysentery cases of pigs highlights the evolving and expanding etiology of SD. Thus, the definition of SD should include all strongly beta-hemolytic Brachyspira species that cause mucohemorrhagic colitis and dysentery in pigs (9). The genetically diverse B. pilosicoli is the primary etiological agent of colonic spirochetosis, a disease characterized by diarrhea and/or colitis in a wide range of host species, including pigs (porcine intestinal spirochetosis [PIS]) (10), chickens (avian intestinal spirochetosis [AIS]) (11), and human beings (human intestinal spirochetosis [HIS]) (12). AIS also can be caused by other Brachyspira species, including B. intermedia (13) and B. alvinipulli (14), while HIS is also caused by B. aalborgi (15). Although long considered to be a commensal, the association of B. murdochii with mild diarrhea and/or colitis in pigs has been reported (16,17). These Brachyspira-associated disease conditions negatively impact the health and welfare of the affected host species and reduce the productivity of livestock (1).Clinical SD was rarely report...

Testing the efficacy of kitasamycin for use in the control and treatment of swine dysentery in experimentally infected pigs

“…Test plates consisted of TSA containing 5% defibrinated ovine blood and the appropriate antibiotic concentration, while control plates did not include antibiotics. The isolates were tested for susceptibility to varying concentrations of kitasamycin (0.675, 1.25, 2.5, 5.0, 10, 20, 40, 80 and 160 μg/mL), tylosin (1, 4, 25, 50 and 100 μg/mL) and lincomycin (2,4,16,36 and 72 μg/mL).…”

“…Swine dysentery (SD) is a potentially severe mucohaemorrhagic colitis of pigs that occurs mainly in the growing and finishing phases of production . SD most commonly results from infection caused by the anaerobic intestinal spirochaete Brachyspira hyodysenteriae , although the related species Brachyspira hampsonii and Brachyspira suanatina may also cause SD in some countries . The latter two species have not been identified in Australia, but B. hyodysenteriae is present in up to a third of Australian herds – including in herds where clinical SD has not been reported …”

“…1 SD most commonly results from infection caused by the anaerobic intestinal spirochaete Brachyspira hyodysenteriae, although the related species Brachyspira hampsonii and Brachyspira suanatina may also cause SD in some countries. 2,3 The latter two species have not been identified in Australia, but B. hyodysenteriae is present in up to a third of Australian herdsincluding in herds where clinical SD has not been reported. 4 No effective commercial vaccines for SD are currently available, and control in infected herds is heavily reliant on prophylactic or therapeutic use of antimicrobials.…”

An Investigation into the Etiological Agents of Swine Dysentery in Australian Pig Herds

“…hyodysenteriae could not be identified. Investigation of these cases led to the recognition of a novel, strongly beta-hemolytic Brachyspira species that recently has been named Brachyspira hampsonii [2,3]. Experimental inoculations of pigs have established the pathogenic potential of this new species [4–6].…”

A review of the current state of antimicrobial susceptibility test methods forBrachyspira

“…This re-emergence has included the identification of novel taxa causing a dysentery-like disease ("Brachyspira hampsonii" and "Brachyspira suanatina") that have been effectively but not validly described (Chander et al 2012;Mushtaq et al 2015;Mirajkar et al 2016b;Perez et al 2016). The specific etiological diagnosis of Brachyspira-associated disease is challenging and relies heavily on polymerase chain reaction (PCR) and culture-based assays.…”