Brachyspira murdochii Colitis in Pigs

Abstract

The weakly beta-hemolytic porcine spirochete Brachyspira murdochii is considered a normal intestinal commensal. In the present study, however, a field case of B murdochii-associated catarrhal colitis was identified in a pig, as characterized by extensive spirochetal colonization of the surface epithelium. Experimentally, 8 weaned pigs were challenged with the B murdochii isolate, reproducing catarrhal colitis in 2 animals. By applying fluorescent in situ hybridization using a species-specific oligonucleotide probe targeting 23S rRNA, B murdochii organisms were found in high numbers and were closely associated with the surface epithelium in the pigs with catarrhal colitis. The results indicate that, when present in high numbers, B murdochii is low pathogenic for pigs. KeywordsInfection trial, Brachyspira murdochii, swine, colitis Spirochetes-long, helically coiled bacteria-are often found in the large intestines of animals affected by diarrhea. The most common porcine intestinal spirochetes comprise several species of the genus Brachyspira: B hyodysenteriae, B pilosicoli, B intermedia, B innocens, and B murdochii.2 The first 2 species are well-known porcine pathogens causing swine dysentery, severe mucohemorrhagic colitis, and the less severe disorder spirochetal colitis. 3,5,6 The importance of the other spirochetes as intestinal pathogens has not yet been investigated thoroughly. In addition to affecting pigs, B murdochii has been isolated from hens 13 and rats (wild and laboratory) 14 without history of intestinal disease. Hitherto, B murdochii has not been considered to be pathogenic, 2,4,11 but the recent detection of B murdochii by polymerase chain reaction (PCR) in cases of porcine colitis negative for B hyodysenteriae and B pilosicoli warrants speculation on the potential pathogenecity of the bacterium. 15The aim of this study was to report a case of naturally acquired colitis and experimental colonic infection caused by B murdochii in pigs. For demonstration of the spirochete in formalin-fixed tissue, fluorescence in situ hybridization (FISH) was developed and applied using an oligonucleotide probe specific for B murdochii.From a farm with suspicion of spirochete-associated colitis, a 9-week-old pig with typical symptoms was euthanized. Intestines, including formalin-fixed ileum and colon samples, were then submitted for routine laboratory examination. The formalin-fixed samples were processed for normal histopathology, embedded in paraffin, and sectioned at 3 mm. Macroscopically, the colonic mucosa was thickened without signs of blood or excess mucus. The colonic contents were liquid. Microscopically, there was catarrhal colitis with large numbers of spirochetes colonizing the surface epithelium and the upper part of the crypts. Sloughing of surface epithelial cells, hyperplasia of crypt enterocytes, necrosis of single crypt enterocytes, and infiltrate of mononuclear cells in lamina propria characterized the colitis, as shown in Fig. 1. Based on in situ hybridization according to Boye et al, 1 w...

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

“…A more recent study from the U.S. confirmed the predominance of B. murdochii amongst Brachyspiraisolates from pigs with mild to moderate mucoid diarrhoea (Hammer and Gebhart, 2013). Hence B. murdochii generally is the most commonly identified weakly haemolytic species in pigs with diarrhoea, including in Spain and Portugal, and this is important given that there is histopathological and experimental infection data supporting its likely role as a pathogen (Weissenböck et al, 2005;Komarek et al, 2009;Jensen et al, 2010). The significance of the other weakly haemolytic species is less clear.…”

“…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). Recently, pigs colonized with one or more of any of these four weakly haemolytic species were shown to have a 5% increase in colonic thickness, and impairment of the colonic mucosa (Fjelkner et al, 2012) and hence interest is refocusing on weakly haemolytic species as potential pathogens.…”

Antimicrobial Susceptibility Patterns of Brachyspira Species Isolated from Swine Herds in the United States

“…A milder enteric syndrome of chronic mucodiarrheal disease of grower-finisher pigs, termed porcine intestinal spirochetosis, is caused by Brachyspira pilosicoli (1). Brachyspira murdochii is commonly isolated from healthy pigs; however, some studies have found it to be associated with mild diarrhea and/or colitis (6,7).…”

Hibridização in situ fluorescente: princípios básicos e perspectivas para o diagnóstico de doenças infecciosas em medicina veterinária

“…Na medicina veterinária, a FISH foi utilizada para diagnosticar vários agentes infecciosos tais como Tritrichomonas foetus (Gookin et al 2010), Lawsonia intracellularis (BoutruP et al, 2010;Jensen et al, 2010a), Pasteurella multocida (Pors et al, 2011a;PORS et al, 2011b), picornavírus (durAnd et al, 2008) (Boye et al, 1998;Jensen et al, 2010b). No trabalho de BoutruP et al (2010), a técnica de FISH foi também utilizada para determinar que a L. intracellularis, frequentemente encontrada no citoplasma de macrófagos na lâmina própria, era viável, indicando que possivelmente possa existir transmissão e proliferação do microorganismo nestas células, além de enterócitos.…”