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Effects of tylosin administration on C-reactive protein concentration and carriage of Salmonella enterica in pigs

September 17, 2014
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OBJECTIVE: To evaluate the effects of tylosin on C-reactive protein concentration, carriage of Salmonella enterica, and antimicrobial resistance genes in commercial pigs. ANIMALS: 120 pigs on 2 commercial farms. PROCEDURES: A cohort of sixty 10-week-old pigs in 4 pens/farm (15 pigs/pen) was randomly selected. Equal numbers of pigs were given feed containing tylosin (40 μg/g…

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Human health impacts of antibiotic use in agriculture: A push for improved causal inference

September 17, 2014
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Resistant bacterial infections in humans continue to pose a significant challenge globally. Antibiotic use in agriculture contributes to this problem, but failing to appreciate the relative importance of diverse potential causes represents a significant barrier to effective intervention. Standard epidemiologic methods alone are often insufficient to accurately describe the relationships between agricultural antibiotic use and…

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Estimation of low quantity genes: a hierarchical model for analyzing censored quantitative real-time PCR data

September 17, 2013
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Analysis of gene quantities measured by quantitative real-time PCR (qPCR) can be complicated by observations that are below the limit of quantification (LOQ) of the assay. A hierarchical model estimated using MCMC methods was developed to analyze qPCR data of genes with observations that fall below the LOQ (censored observations). Simulated datasets with moderate to…

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Livestock density as risk factor for livestock-associated methicillin-resistant Staphylococcus aureus, The Netherlands

September 17, 2013
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Confusion over antibiotic resistance: ecological correlation is not evidence of causation

September 17, 2012
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Microbial shifts in the swine distal gut in response to the treatment with antimicrobial growth promoter, tylosin

September 17, 2012
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Antimicrobials have been used extensively as growth promoters (AGPs) in agricultural animal production. However, the specific mechanism of action for AGPs has not yet been determined. The work presented here was to determine and characterize the microbiome of pigs receiving one AGP, tylosin, compared with untreated pigs. We hypothesized that AGPs exerted their growth promoting…

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Quantitative measurement of bla(CMY-2) in a longitudinal observational study of dairy cattle treated with ceftiofur

September 17, 2012
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There is concern that a relationship exists between antibiotic use in livestock production and the emergence, spread, and persistence of antibiotic resistance. It is important to understand the impact that therapeutic doses of antibiotics for treatment of disease have on resistance because disease treatment typically involves higher doses of antibiotic over short time spans. Absolute…

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The direct relationship between animal health and food safety outcomes

September 17, 2012
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The health of the animals within the food animal production system impacts many aspects of the system far removed from the animals themselves. To promote high productivity in animal agriculture, researchers need to examine nutrition, management systems, and animal care practices including the use of antibiotics and vaccines. This Commentary looks at the pressures to…

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Use estimates of in-feed antimicrobials in swine production in the United States

September 17, 2012
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When considering the development of antimicrobial resistance in food animals, comparing gross use estimates of different antimicrobials is of little value due to differences in potencies, duration of activity, relative effect on target and commensal bacteria, and mechanisms of resistance. However, it may be valuable to understand quantities of different antimicrobials used in different ages…

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Comparative genomics of multidrug resistance-encoding IncA/C plasmids from commensal and pathogenic Escherichia coli from multiple animal sources

September 17, 2011
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Incompatibility group A/C (IncA/C) plasmids have received recent attention for their broad host range and ability to confer resistance to multiple antimicrobial agents. Due to the potential spread of multidrug resistance (MDR) phenotypes from foodborne pathogens to human pathogens, the dissemination of these plasmids represents a public health risk. In this study, four animal-source IncA/C plasmids isolated from…

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Horizontal gene transfer of a ColV plasmid has resulted in a dominant avian clonal type of Salmonella enterica serovar Kentucky

September 17, 2010
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Salmonella enterica continues to be a significant cause of foodborne gastrointestinal illness in humans. A wide variety of Salmonella serovars have been isolated from production birds and from retail poultry meat. Recently, though, S. enterica subsp. enterica serovar Kentucky has emerged as one of the prominent Salmonella serovars isolated from broiler chickens. Recent work suggests…

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Novel florfenicol and chloramphenicol resistance gene discovered in Alaskan soil by using functional metagenomics

September 17, 2010
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Functional metagenomics was used to search for florfenicol resistance genes in libraries of cloned DNA isolated from Alaskan soil. A gene that mediated reduced susceptibility to florfenicol was identified and designated pexA. The predicted PexA protein showed a structure similar to that of efflux pumps of the major facilitator superfamily.

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Detection of the floR gene in a diversity of florfenicol resistant Gram-negative bacilli from freshwater salmon farms in Chile

September 17, 2010
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Florfenicol is an important antibiotic in veterinary medicine that is used extensively in aquaculture, including salmon farming in Chile. We analysed a set of 119 florfenicol-resistant Gram-negative bacilli from seven freshwater Chilean salmon farms for the molecular determinants involved in the florfenicol resistance. Ninety-seven of these strains were glucose non-fermenting bacilli, mainly belonging to the…

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blaCMY-2-positive IncA/C plasmids from Escherichia coli and Salmonella enterica are a distinct component of a larger lineage of plasmids

September 17, 2010
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Large multidrug resistance plasmids of the A/C incompatibility complex (IncA/C) have been found in a diverse group of Gram-negative commensal and pathogenic bacteria. We present three completed sequences from IncA/C plasmids that originated from Escherichia coli (cattle) and Salmonella enterica serovar Newport (human) and that carry the cephamycinase gene blaCMY-2. These large plasmids (148 to…

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Evaluation of in vitro bactericidal activity of commercial disinfectants against Lawsonia intracellularis

February 23, 2010
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Objective: To evaluate the bactericidal activity of seven commercial disinfectants against Lawsonia intracellularis using a tissue culture system. Materials and methods: Two L intracellularis isolates were tested for susceptibility to several classes of disinfectants, including iodine, a biguanide, phenol, an oxidizing agent, a quaternary ammonium compound (QAC), and the combinations of QACs with aldehydes (formaldehyde and glutaraldehyde). All disinfectants were diluted…

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