EPIDEMIOLOGY, ECOLOGY, AND MOLECULAR GENETICS OF ANTIMICROBIAL RESISTANCE IN PATHOGENIC AND COMMENSAL BACTERIA FROM FOOD ANIMALS
Location: Bacterial Epidemiology and Antimicrobial Resistance
Title: Genetic Variability in Multi-Drug Resistant Salmonella Newport Associated with Dairy Cattle and S. Kentucky Associated with Poultry
Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: May 23, 2010
Publication Date: May 23, 2010
Citation: Turpin, J.B., Cray, P.J., Frye, J.G. 2010. Genetic Variability in Multi-Drug Resistant Salmonella Newport Associated with Dairy Cattle and S. Kentucky Associated with Poultry. American Society for Microbiology. May 23-27, 2010. San Diego, CA. CD ROM. Z-973.
Background: Differences in pathogenesis and ecological niches make Salmonella Newport and S. Kentucky candidates for the study of genetic variability. S. Kentucky is the top serotype isolated from broilers; however it is infrequently associated with human illness. In contrast, S. Newport is both a top serotype isolated from cattle and also causes human illness. Materials and Methods: Salmonella Newport (n=25) and S. Kentucky isolates (n=10) were selected from the National Antimicrobial Resistance Monitoring System to represent the highest genetic diversity possible as determined by PFGE analysis. DNA was extracted and subjected to comparative genomic hybridizations (CGH) using standard methods to a non-redundant Salmonella whole genome array representing six sequenced Salmonella isolates (Typhimurium LT2, Typhimurium SL1344, Typhi strain CT18, Typhi Ty2, Paratyphi A SARB42 and S. Enteritidis PT4). Hybridization results of the 5,660 genes on the array were analyzed by Bionumerics (V 6.0, Applied Maths Austin, TX, USA). Data from CGH experiments and the published genomes of S. Newport and Kentucky (NCBI database) were compared using MAUVE (The University of Wisconsin-Madison, Madison, WI, USA). Results: CGH of S. Newport revealed high genomic similarity within MDR strains consistent with previous findings. Analysis of sequences in the NCBI database also identified genes unique to S. Newport (n=100) and Kentucky (n=177). Genetic comparisons identified differences between Kentucky and Newport including genes involved in metabolic function (n=32), cell motility (n=11), cell wall biosynthesis (n=15), cellular metal ion homeostasis (n=20), DNA replication, recombination, and repair (n=31), phage (n=39), and hypothetical proteins (n=195). Conclusion: Genes unique to S. Newport and Kentucky were identified as well as differences in gene content between them. Unique genes identified in these serotypes may contribute to the different niches S. Newport and S. Kentucky reside in, including S. Newport’s ability to colonize humans and S. Kentucky’s ability to persist in the poultry environment.