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Fecal shedding of Brachyspira spp. on a farrow-to-finish swine farm with a clinical history of "Brachyspira hampsonii"-associated colitis.

Patterson AH, Rubin JE, Fernando C, Costa MO, Harding JC, Hill JE - BMC Vet. Res. (2013)

Bottom Line: To identify critical control points for reducing the impact of Brachyspira on production, improved diagnostic tools and a better understanding of the on-farm epidemiology of these pathogens are required.Phylogenetic analysis revealed that several of the isolates, including some strongly beta-haemolytic isolates, might represent novel taxa.Our results indicate that apparently healthy pigs can be colonized with diverse Brachyspira species, including some potential pathogens, and that frequency of shedding peaks in the grower stage.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada.

ABSTRACT

Background: Brachyspira associated diarrhea is a re-emerging concern for Canadian swine producers. To identify critical control points for reducing the impact of Brachyspira on production, improved diagnostic tools and a better understanding of the on-farm epidemiology of these pathogens are required. A cross-sectional study was conducted for the detection of Brachyspira on a commercial, two-site, farrow-to-finish pork production unit in Saskatchewan, Canada with a clinical history of mucohaemorrhagic colitis associated with "B. hampsonii".

Results: Rectal swabs from pigs at all production stages were collected over 13 weeks (n=866). Two swabs were collected per pig for culture and Gram stain, and for PCR. Ninety-one culture positive samples were detected, with the highest prevalence of Brachyspira shedding in grower pigs (21%). No Brachyspira were detected in pre-weaned piglets. PCR and Gram stain of rectal swabs detected fewer positive samples than culture. The most prevalent species detected was B. murdochii; other species detected included B. pilosicoli, B. innocens, and "Brachyspira hampsonii". Phylogenetic analysis revealed that several of the isolates, including some strongly beta-haemolytic isolates, might represent novel taxa.

Conclusions: Our results indicate that apparently healthy pigs can be colonized with diverse Brachyspira species, including some potential pathogens, and that frequency of shedding peaks in the grower stage. Difference in the detection rates of Brachyspira amongst culture, Gram stain or PCR on rectal swabs have implications for choice of detection methods and surveillance approaches that may be most effective in Brachyspira control strategies.

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Phylogenetic tree of partial nox gene sequences from 81 cultured Brachyspira isolates. Representative strains of recognized species are included for reference. Numbers at the nodes indicate bootstrap values out of 100 iterations. Scale bar indicates number of substitutions per site. Production stage is indicated by colour (legend) and square markers indicate strongly beta-haemolytic isolates. Genbank accession numbers are indicated in parentheses for published sequences. Clusters of unclassified isolates (Clusters 1, 2 and 3) are indicated, and discussed in the text.
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Figure 2: Phylogenetic tree of partial nox gene sequences from 81 cultured Brachyspira isolates. Representative strains of recognized species are included for reference. Numbers at the nodes indicate bootstrap values out of 100 iterations. Scale bar indicates number of substitutions per site. Production stage is indicated by colour (legend) and square markers indicate strongly beta-haemolytic isolates. Genbank accession numbers are indicated in parentheses for published sequences. Clusters of unclassified isolates (Clusters 1, 2 and 3) are indicated, and discussed in the text.

Mentions: A phylogenetic analysis of the partial nox sequences determined for 81 study isolates is shown in Figure 2 (nox sequences of two isolates were too short for inclusion). Three clusters (Clusters 1, 2 and 3) and several single isolates grouped separately from any reference sequences with good bootstrap support. As expected, isolates corresponding to “B. hampsonii” strains 30599 and 30446 (corresponding to “clade I” and “clade II” of “B. hampsonii”, respectively [4]) were strongly beta-haemolytic, but strongly beta-haemolytic isolates were also detected among B. murdochii-like isolates (8/49 isolates), although most B. murdochii isolates (41/49) were weakly beta-haemolytic as expected based on the species definition. Strongly beta-haemolytic isolates were also identified among isolates in Cluster 1 (2/6 isolates), Cluster 2 (2/4 isolates) and Cluster 3 (3/12 isolates) (Figure 2). These strongly beta-haemolytic isolates were cultured from rectal swabs of all culture-positive age groups, but most (13/18, 72%) were from Site 2. Surprisingly few “B. hampsonii” isolates were found, and only in the finisher group at Site 2. B. innocens was detected only in gilts and sows at Site 1 (Figure 1). Other phylogenetic groups were identified in pigs from both production sites and a mixture of production stages.


Fecal shedding of Brachyspira spp. on a farrow-to-finish swine farm with a clinical history of "Brachyspira hampsonii"-associated colitis.

Patterson AH, Rubin JE, Fernando C, Costa MO, Harding JC, Hill JE - BMC Vet. Res. (2013)

Phylogenetic tree of partial nox gene sequences from 81 cultured Brachyspira isolates. Representative strains of recognized species are included for reference. Numbers at the nodes indicate bootstrap values out of 100 iterations. Scale bar indicates number of substitutions per site. Production stage is indicated by colour (legend) and square markers indicate strongly beta-haemolytic isolates. Genbank accession numbers are indicated in parentheses for published sequences. Clusters of unclassified isolates (Clusters 1, 2 and 3) are indicated, and discussed in the text.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3716975&req=5

Figure 2: Phylogenetic tree of partial nox gene sequences from 81 cultured Brachyspira isolates. Representative strains of recognized species are included for reference. Numbers at the nodes indicate bootstrap values out of 100 iterations. Scale bar indicates number of substitutions per site. Production stage is indicated by colour (legend) and square markers indicate strongly beta-haemolytic isolates. Genbank accession numbers are indicated in parentheses for published sequences. Clusters of unclassified isolates (Clusters 1, 2 and 3) are indicated, and discussed in the text.
Mentions: A phylogenetic analysis of the partial nox sequences determined for 81 study isolates is shown in Figure 2 (nox sequences of two isolates were too short for inclusion). Three clusters (Clusters 1, 2 and 3) and several single isolates grouped separately from any reference sequences with good bootstrap support. As expected, isolates corresponding to “B. hampsonii” strains 30599 and 30446 (corresponding to “clade I” and “clade II” of “B. hampsonii”, respectively [4]) were strongly beta-haemolytic, but strongly beta-haemolytic isolates were also detected among B. murdochii-like isolates (8/49 isolates), although most B. murdochii isolates (41/49) were weakly beta-haemolytic as expected based on the species definition. Strongly beta-haemolytic isolates were also identified among isolates in Cluster 1 (2/6 isolates), Cluster 2 (2/4 isolates) and Cluster 3 (3/12 isolates) (Figure 2). These strongly beta-haemolytic isolates were cultured from rectal swabs of all culture-positive age groups, but most (13/18, 72%) were from Site 2. Surprisingly few “B. hampsonii” isolates were found, and only in the finisher group at Site 2. B. innocens was detected only in gilts and sows at Site 1 (Figure 1). Other phylogenetic groups were identified in pigs from both production sites and a mixture of production stages.

Bottom Line: To identify critical control points for reducing the impact of Brachyspira on production, improved diagnostic tools and a better understanding of the on-farm epidemiology of these pathogens are required.Phylogenetic analysis revealed that several of the isolates, including some strongly beta-haemolytic isolates, might represent novel taxa.Our results indicate that apparently healthy pigs can be colonized with diverse Brachyspira species, including some potential pathogens, and that frequency of shedding peaks in the grower stage.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada.

ABSTRACT

Background: Brachyspira associated diarrhea is a re-emerging concern for Canadian swine producers. To identify critical control points for reducing the impact of Brachyspira on production, improved diagnostic tools and a better understanding of the on-farm epidemiology of these pathogens are required. A cross-sectional study was conducted for the detection of Brachyspira on a commercial, two-site, farrow-to-finish pork production unit in Saskatchewan, Canada with a clinical history of mucohaemorrhagic colitis associated with "B. hampsonii".

Results: Rectal swabs from pigs at all production stages were collected over 13 weeks (n=866). Two swabs were collected per pig for culture and Gram stain, and for PCR. Ninety-one culture positive samples were detected, with the highest prevalence of Brachyspira shedding in grower pigs (21%). No Brachyspira were detected in pre-weaned piglets. PCR and Gram stain of rectal swabs detected fewer positive samples than culture. The most prevalent species detected was B. murdochii; other species detected included B. pilosicoli, B. innocens, and "Brachyspira hampsonii". Phylogenetic analysis revealed that several of the isolates, including some strongly beta-haemolytic isolates, might represent novel taxa.

Conclusions: Our results indicate that apparently healthy pigs can be colonized with diverse Brachyspira species, including some potential pathogens, and that frequency of shedding peaks in the grower stage. Difference in the detection rates of Brachyspira amongst culture, Gram stain or PCR on rectal swabs have implications for choice of detection methods and surveillance approaches that may be most effective in Brachyspira control strategies.

Show MeSH
Related in: MedlinePlus