ARS | Publication request: Analysis of Antimicrobial Resistance Genes in Multiple Drug Resistant (MDR) Salmonella enterica Isolated from Animals and Humans

Submitted to: American Society for Microbiology General Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 23, 2011
Publication Date: May 24, 2011
Citation: Glenn, L.M., Lindsey, R.L., Boerlin, P., Gilmour, M.W., Harbottle, H., Cray, P.J., Frye, J.G. 2011. Analysis of Antimicrobial Resistance Genes in Multiple Drug Resistant (MDR) Salmonella enterica Isolated from Animals and Humans. American Society for Microbiology General Meeting. pg. 161. Poster# 2016.

Technical Abstract: Background: Multiple Drug Resistant (MDR) foodborne bacteria are a concern in animal and human health. Identification of resistance genes in foodborne pathogens is necessary to determine similarities of resistance mechanisms in animal, food and human clinical isolates. This information will help us understand the relationship of antimicrobial resistant bacteria in animals and humans. Methods: MDR Salmonella were isolated from healthy poultry, cattle, and swine, retail meat, and human infections. These included U.S. slaughter (n=12) and retail isolates (n=9, both from NARMS, ARS, USDA, Athens, GA, U.S.), Canadian slaughter (n=9, from Ontario Veterinary College, Guelph ON, Canada) and retail isolates (n=9), U.S. human (n=9, from Centers for Disease Control and Prevention, Atlanta, GA, U.S.) and Canadian human isolates (n=8, from Public Health Agency of Canada, Winnipeg MB, Canada). These isolates were assayed by microarray for 1,267 antimicrobial resistance and MDR plasmid genes. Results: Genes detected encoded resistance to aminoglycosides (aac, aadA, aph, strA/B); beta-lactams (blaAMP, blaTEM, blaCMY, blaPSE); chloramphenicol (cat, flo, cmlA); sulfamethoxazole (sulI); tetracycline (tet(A, C, D, R)); and trimethoprim (dfrA, dhrf, dhf). Three US retail isolates had core IncA/C plasmid genes detected, indicating IncA/C plasmid presence. None of the Canadian retail or slaughter isolates contained IncA/C plasmids; however one retail isolate contained a HI1 plasmid. Ten U.S. slaughter isolates contained IncA/C plasmids, as well as eight U.S. and three Canadian human isolates. Conclusions: Similar resistance genes were found among the isolates regardless of source or country. IncA/C plasmids were detected in U.S. retail and slaughter isolates but not Canadian retail or slaughter isolates. These plasmids were also detected in U.S. and Canadian human isolates. The prevalence of IncA/C plasmids may indicate the importance of these genetic elements in the spread of antimicrobial resistance genes in the animal and human microbial community in the U.S.; however, further investigation is necessary to determine if other factors play a role in Canadian microbial populations.