Comparison of Lesion Severity, Distribution, and Colonic Mucin Expression in Pigs With Acute Swine Dysentery Following Oral Inoculation With “Brachyspira hampsonii” or Brachyspira hyodysenteriae

Abstract

Swine dysentery is classically associated with infection by Brachyspira hyodysenteriae, the only current officially recognized Brachyspira sp. that consistently imparts strong beta-hemolysis on blood agar. Recently, several strongly beta-hemolytic Brachyspira have been isolated from swine with clinical dysentery that are not identified as B. hyodysenteriae by PCR including the recently proposed species "Brachyspira hampsonii." In this study, 6-week-old pigs were inoculated with either a clinical isolate of "B. hampsonii" (EB107; n = 10) clade II or a classic strain of B. hyodysenteriae (B204; n = 10) to compare gross and microscopic lesions and alterations in colonic mucin expression in pigs with clinical disease versus controls (n = 6). Gross lesions were similar between infected groups. No histologic difference was observed between infected groups with regard to neutrophilic inflammation, colonic crypt depth, mucosal ulceration, or hemorrhage. Histochemical and immunohistochemical evaluation of the apex of the spiral colon revealed decreased expression of sulphated mucins, decreased expression of MUC4, and increased expression of MUC5AC in diseased pigs compared to controls. No difference was observed between diseased pigs in inoculated groups. This study reveals significant alterations in colonic mucin expression in pigs with acute swine dysentery and further reveals that these and other microscopic changes are similar following infection with "B. hampsonii" clade II or B. hyodysenteriae.

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

“…The resulting disease was indistinguishable from SD caused by B. hyodysenteriae on the basis of clinical signs and gross pathology. Examination of tissues obtained from the experimentally infected pigs had microscopic lesions consistent with those seen in the mucohemorrhagic colitis induced by B. hyodysenteriae (28)(29)(30). Currently, no differences in clinical signs or gross and microscopic pathology have been reported in the SD caused by either genetic group I or II of B. hampsonii.…”

“…While both genotypic and phenotypic data clearly support B. hampsonii as a novel species, they provide ambiguous interpretations for whether the various genetic groups represent one or multiple novel species. Specifically, although the genomic indices (GGD, ANI, and AAI [7], MLST [31], MLSA [31], GGD, ANI, and AAI) reliably discriminate several genetic groups of B. hampsonii, currently, analysis of the available phenotypic properties (i.e., beta-hemolysis on blood agar [7], biochemical profiles [7], MALDI protein spectra [26], antibiograms [27], and pathogenicity [28][29][30]) is unable to clearly and consistently differentiate them. Thus, based on a comprehensive genotypic, phenotypic, and genomic evaluation, we propose that Brachyspira hampsonii sp.…”

“…Although B. hampsonii often demonstrated a more susceptible antibiogram than other Brachyspira species, no clear differences in antibiogram profiles were observed between its genetic groups (27). Finally, several trials have reproduced mucohemorrhagic diarrhea in pigs by oral inoculation of B. hampsonii genetic groups I and II under experimental conditions and have thus confirmed the pathogenic nature of both groups (28)(29)(30). The resulting disease was indistinguishable from SD caused by B. hyodysenteriae on the basis of clinical signs and gross pathology.…”

Comparison of culture, polymerase chain reaction, and fluorescent in situ hybridization for detection of Brachyspira hyodysenteriae and “Brachyspira hampsonii” in pig feces

“…8 However, a recently proposed novel Brachyspira species, "Brachyspira hampsonii ", 5 has been isolated from pigs with mucohemorrhagic diarrhea, and experimental infection with "B. hampsonii " strains has consistently resulted in clinical disease and gross lesions that are similar to, if not indistinguishable from, B. hyodysenteriae infection. 3,12,14 A definitive diagnosis of SD is commonly based on the isolation of strongly beta-hemolytic, ring phenomenon-positive spirochetes from culture of mucohemorrhagic feces or colonic tissue and/or by species-specific polymerase chain reaction (PCR) assays run on extracts of such samples. 4 While Brachyspira culture using selective agars is a highly sensitive assay, it can be technically challenging, time consuming, typically requires speciation using PCR following isolation, and often requires 6 days or longer to complete, which can result in a delay in disease diagnosis.…”

Hibridização in situ fluorescente para diagnóstico de Brachyspira hyodysenteriae e B. pilosicoli em suínos

“…Outras espécies não patogênicas de Brachyspira (B. innocens e B. murdochii) são habitantes normais do intestino grosso de suínos, o que pode dificultar o diagnóstico. O quadro clinico de diarreia muco hemorrágica, altas taxas de mortalidade, e lesões graves de enterite muco hemorrágica associada a áreas de necrose são indistinguíveis entre casos de infecção por B. hyodysenteriae e B. hampsonii (Burrough et al 2012, Rubin et al 2013, Wilberts et al 2014, mas B. hampsonii nunca foi diagnosticada no Brasil. Já a infecção por B. pilosicoli causa diarreia pastosa acinzentada com comprometimento do ganho de peso de animais recentemente alojados na fase de recria.…”