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Abstract
Salmonella remains one of the leading causes of foodborne illnesses; however information regarding the distribution and genomics of plasmids other than the virulence plasmid is limited. In this study, we characterized the diversity of large molecular weight plasmids in Salmonella isolated from a diverse group of vertebrate hosts to determine if distribution of large molecular weight plasmids is affected by the carriage of the virulence plasmid. Few plasmids other than the virulence plasmid were detected among a diverse group of Typhimurium isolates, although novel plasmids were detected among other serotypes. DNA sequencing of novel plasmids isolated from Salmonella groups C1 and H revealed genetic similarities to two newly characterized Salmonella plasmids and identified novel conjugation systems. While transposons and colicin genes were identified, no antibiotic or heavy metal resistance genes were identified. While some serotypes may not exhibit the propensity to harbor multiple plasmids within their genome, other Salmonella isolates have acquired unique plasmids from unknown bacterial hosts. These results indicate that there are unknown genetic barriers to plasmid acquisition in some salmonellae. INDEX WORDS: Salmonella Typhimurium, plasmid distribution, antibiotic resistance