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The overall goal of this research is to provide basic knowledge on antimicrobial resistance, virulence and conjugative ability in Salmonella Newport isolates found in beef carcasses and hides from US slaughterhouses by genetically determining multidrug resistance status, pathogenicity and ability to transfer and/or uptake such genes in a Salmonella spp. of public health concern causing substantive costs to the beef cattle industry due to fatal disease in cattle prior to slaughter as well as food poisoning and more serious human cases.
Approach: 1. Characterization of antibiotic resistance and virulence genes in Salmonella enterica serovar Newport isolated from slaughterhouse hide and carcass samples (to be provided by Dr. Koomahrie, USDA/ARS). a) Perform initial phenotypic characterization of unknown isolates from antimicrobial susceptibility tests and pulsed field-gel electrophoresis to use as basis for prediction of genotype and further studies. b) Design a microarray for identifying serovar (strain or species specific genes), detecting virulence and antimicrobial resistance genes (including class I integrons and other transposable elements) in Salmonella serovars including S. Newport based on published information. c) Investigate the correlation between antimicrobial resistance phenotype and genotype, as well as predicted pathogenicity and presence of predisposing conjugative elements and competitive fitness, for each isolate tested. 2. Comparison of previously characterized Salmonella enterica and E. coli isolates with Newport isolates characterized in this study to compare antibiotic resistance and virulence genetic profiles as well as predict competitive fitness from presence of mobile elements.