Novel method for measuring growth of Treponema hyodysenteriae and its application for monitoring susceptibility of clinical isolates to antimicrobial agents.
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A microdilution assay method was developed to determine MICs of antibiotics for Treponema hyodysenteriae and to estimate the bacterial burden of mice colonized by this swine pathogen. Hemolysis of bovine erythrocytes in broth was correlated with growth of the spirochete, and growth inhibition by drugs could be determined by measuring hemolysis. MICs of 10 antibiotics for eight clinical isolates of T. hyodysenteriae measured by this method were similar to values obtained by an agar dilution method and to values reported in the literature. This method was also used to demonstrate the elimination of T. hyodysenteriae from the ceca of infected mice following oral treatment with carbadox. The procedure described in this paper provides a rapid and simple method for determining MICs of antibiotics for T. hyodysenteriae and may be adapted for the purpose of determining the presence of this veterinary pathogen in cecal contents of experimentally infected mice. (+info)
Effect of sodium butyrate on growth performance and response to lipopolysaccharide in weanling pigs.
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Two experiments were conducted to determine the effects of dietary sodium butyrate on growth performance and response to Escherichia coli lipopolysaccharide (LPS) in weanling pigs. In a 28-d experiment, 180 pigs (initial BW 6.3 kg) were fed 0, 0.05, 0.1, 0.2, or 0.4% sodium butyrate, or 110 mg/kg of dietary tylosin. There was no effect of dietary sodium butyrate or tylosin on overall G:F, but there was a linear trend (P < 0.07) toward decreased ADFI and ADG as levels of sodium butyrate increased. In a second 28-d experiment, 108 pigs (initial BW 6.3 kg) were assigned to 1 of 3 dietary treatments: 1) no antibiotics, 2) 0.2% sodium butyrate, or 3) 55 mg/kg of carbadox. On d 14, a subset of pigs from the no-antibiotic and butyrate treatment groups was challenged with E. coli LPS or injected with sterile saline in a 2 x 2 factorial arrangement (+/-LPS challenge; +/-dietary butyrate; n = 6 pigs/treatment group). Four hours after LPS challenge, blood samples were obtained, and samples of LM, liver, and ileum were collected for gene expression analysis. Serum samples were analyzed for IL-6, tumor necrosis factor alpha (TNFalpha), alpha(1)-acid glycoprotein, cortisol, IGF-I, insulin, and metabolites. The relative abundance of tissue cytokine and IGF-I mRNA was measured by real-time PCR. Feeding diets containing sodium butyrate or carbadox did not alter ADG or ADFI compared with pigs fed the control diet. From d 0 to 14, pigs fed diets containing 0.2% sodium butyrate had decreased (P < 0.05) ADG and tended (P < 0.06) to have decreased G:F compared with animals fed diets containing carbadox. Challenge with LPS increased (P < 0.05) serum cytokines and cortisol and decreased (P < 0.05) serum glucose and triglycerides. Injection with LPS increased (P < 0.05) the relative abundance of hepatic IL-6 and TNFalpha mRNA, increased (P < 0.05) LM TNFalpha mRNA content, and decreased (P < 0.05) IGF-I mRNA in LM. For serum cortisol, there was an interaction (P < 0.05) between dietary butyrate and LPS. The increase in serum cortisol attributable to LPS was greater (P < 0.05) in pigs fed butyrate than in pigs fed the control diet. There tended (P < 0.10) to be an interaction between LPS and diet and for butyrate to increase the relative abundance of IL-6 mRNA in LM. Carbadox did not alter cytokine or IGF-I mRNA or serum metabolites, but did decrease (P < 0.05) serum TNFalpha. These data indicate that dietary sodium butyrate does not enhance growth performance, but may regulate the response to inflammatory stimuli in weanling pigs. (+info)
Collateral effects of antibiotics: carbadox and metronidazole induce VSH-1 and facilitate gene transfer among Brachyspira hyodysenteriae strains.
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Minimal inhibitory concentrations of five antimicrobials against Treponema hyodysenteriae and Treponema innocens.
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The minimal inhibitory concentrations of carbadox, dimetridazole, lincomycin, ronidazole, and tiamulin against isolates of Treponema hyodysenteriae and Treponema innocens were determined by an agar-dilution method. The results obtained indicated that tiamulin was the most effective antimicrobial in vitro against T. hyodysenteriae, followed by carbadox. Dimetridazole, lincomycin, and ronidazole had poor efficacy in vitro against the T. hyodysenteriae isolates. Isolates of T. innocens were more sensitive to the various antimicrobials. Carbadox and tiamulin were the most effective in vitro, followed by ronidazole, dimetridazole, and lincomycin. (+info)
Growth performance and gastrointestinal microbial ecology responses of piglets receiving Saccharomyces cerevisiae fermentation products after an oral challenge with Escherichia coli (K88).
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Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids. Part I: effects on growth performance, microbial populations, and immune status.
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