Reproduction of Mucohaemorrhagic Diarrhea and Colitis Indistinguishable from Swine Dysentery following Experimental Inoculation with “Brachyspira hampsonii” Strain 30446
Open Access
- 27 February 2013
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 8 (2), e57146
- https://doi.org/10.1371/journal.pone.0057146
Abstract
Mucohaemorrhagic diarrhea caused by Brachyspira hyodysenteriae, swine dysentery, is a severe production limiting disease of swine. Recently, pigs in western Canada with clinical signs indistinguishable from swine dysentery were observed. Despite the presence of spirochetes on fecal smears, recognized Brachyspira spp. including B. hyodysenteriae could not be identified. A phylogenetically distinct Brachyspira, called “B. hampsonii” strain 30446, however was isolated. The purpose of this study was to experimentally reproduce mucohaemorrhagic colitis and characterize strain 30446 shedding following inoculation. Eighteen 13-week-old pigs were randomly assigned to inoculation (n = 12) or control (n = 6) groups in each of two trials. In trial 1, pigs were inoculated with a tissue homogenate collected from clinically affected field cases. In trial 2, pigs were inoculated with a pure broth culture of strain 30446. In both trials, mucohaemorrhagic diarrhea was significantly more common in inoculated pigs than controls, all of which remained healthy. In animals with mucohaemorrhagic diarrhea, significantly more spirochetes were observed on Gram stained fecal smears, and higher numbers of strain 30446 genome equivalents were detected by quantitative PCR (qPCR). Strain 30446 was cultured from colon and/or feces of all affected but no control animals at necropsy. “Brachyspira hampsonii” strain 30446 causes mucohaemorrhagic diarrhea in pigs following a 4–9 day incubation period. Fecal shedding was detectable by day 4 post inoculation, and rarely preceded the onset of mucoid or haemorrhagic diarrhea by more than 2 days. Culture and 30446-specific qPCR are reliable methods of detection of this organism in feces and tissues of diarrheic pigs. The emergence of a novel Brachyspira spp., such as “B. hampsonii”, creates diagnostic challenges including higher risk of false negative diagnostic tests. We therefore recommend diagnostic laboratories routinely use Brachyspira culture, nox-based and species-specific PCR, and DNA sequencing to diagnose Brachyspira-associated colitis in pigs.Keywords
This publication has 18 references indexed in Scilit:
- Brachyspira murdochii Colitis in PigsVeterinary Pathology, 2009
- Infections with weakly haemolytic Brachyspira species in pigs with miscellaneous chronic diseasesVeterinary Microbiology, 2009
- Development of a multilocus sequence typing scheme for intestinal spirochaetes within the genus BrachyspiraMicrobiology, 2007
- A novel enteropathogenic, strongly haemolytic spirochaete isolated from pig and mallard, provisionally designated ‘Brachyspira suanatina’ sp. nov.Environmental Microbiology, 2007
- Assessment of diagnostics and antimicrobial susceptibility testing of Brachyspira species using a ring testVeterinary Microbiology, 2005
- Experimental swine dysentery: comparison between infection modelsJournal of Medical Microbiology, 2004
- Differentiation of Porcine Brachyspira Species by a Novel nox PCR-Based Restriction Fragment Length Polymorphism AnalysisJournal of Clinical Microbiology, 2002
- Differentiation of Serpulina species by NADH oxidase gene (nox) sequence comparisons and nox-based polymerase chain reaction testsVeterinary Microbiology, 1999
- Serpulina pilosicoli sp. nov., the Agent of Porcine Intestinal SpirochetosisInternational Journal of Systematic and Evolutionary Microbiology, 1996
- Selective medium for the isolation of Treponema hyodysenteriaeVeterinary Record, 1981