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The current model is that food-borne pathogens obtain most antibiotic resistance from a pre-existing pool of drug resistance genes in resident benign bacteria of healthy animals. </p>
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To assess how rapidly drug resistance develops and how long it persists in animals colonized with Salmonella, we will examine the distribution of drug resistance genes among the microbial fauna present on poultry farms.</p>
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The emergence of multiple-drug resistant Salmonella has made antibiotic resistance an important, health issue in medicine and food safety. Once antibiotics are introduced, antimicrobial resistance quickly develops, spreads, and persists, even when antibiotic usage is discontinued. </P>
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We will identify by PCR and DNA-DNA hybridization, drug resistance genes common to both Salmonella and resident bacteria in chickens. </p>
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Specific emphasis will be placed on tracking integrons, mobile genetic elements responsible for the diversity and rapid evolution of multiple drug resistant bacteria. A novel 'integron capture' plasmid will be introduced to the chicken's microflora and followed during the normal rearing period for broiler chickens. </p>
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The plasmid will be periodically isolated to examine the drug resistance genes acquired by the plasmid's resident integron during the vector's passage among the microbial community of the chicken's gastrointestinal tract.</p>
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Experiments will be performed in a high-security level, biocontainment facility. Clear definition of the genetic elements within the chicken normal flora that facilitate genetic exchange and persistence of multiple antibiotic resistance will permit realistic risk assessment of the role of poultry Salmonella as reservoirs of antibiotic resistance and agents in its transmission to other animals and humans.</p>