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Abstract
The genome projects have supplied a rich source of genetic data regarding chromosome structure and gene transfer. In this study, we utilized a genomic approach to assess the epidemiological relatedness of atypical Salmonella isolates and the ability of Salmonella to acquire antibiotic resistance genes. Genetic relatedness of an atypical serovar (4,5,12:i:-) was investigated to determine whether it was closely related to a common serovar S. Typhimurium. We have found that Salmonella 4,5,12:i:- strains isolated from poultry do not represent the emergence of a new serovar or clone, rather the result of spontaneous mutations in endemic S. Typhimurium strains, affecting phase 2 antigen expression. We also measured different variables involved in transfer of plasmid to Salmonella in vitro and assessed what factors affect this process. The data provided information relevant for validating a mathematical model of plasmid transmission to Salmonella. Our long term goal is to understand the process underlying the acquisition and spread of multiple drug resistance among major foodborne pathogens.