title: Identification and Characterization of Cefotaxime Resistant Bacteria in Beef Cattle.
abstract: Third-generation cephalosporins are an important class of antibiotics that are widely used in treatment of serious Gram-negative bacterial infections. In this study, we report the isolation of bacteria resistant to the third-generation cephalosporin cefotaxime from cattle with no previous cefotaxime antibiotic exposure. The prevalence of cefotaxime-resistant bacteria was examined by a combination of culture based and molecular typing methods in beef cattle (n = 1341) from 8 herds located in North Central Florida. The overall prevalence of cefotaxime-resistant bacteria was 15.8% (95% CI: 13.9, 17.8), varied between farms, and ranged from 5.2% to 100%. A subset of isolates (n = 23) was further characterized for the cefotaxime minimum inhibitory concentration (MIC) and antibiotic susceptibility against 10 different antibiotics, sequencing of nine β- lactamase genes, and species identification by 16S rRNA sequencing. Most of the bacterial isolates were resistant to cefotaxime (concentrations, > 64 μg/mL) and showed high levels of multi-drug resistance. Full length 16S rRNA sequences (~1300 bp) revealed that most of the isolates were not primary human or animal pathogens; rather were more typical of commensal, soil, or other environmental origin. Six extended spectrum β-lactamase (ESBL) genes identical to those in clinical human isolates were identified. Our study highlights the potential for carriage of cefotaxime resistance (including "human" ESBL genes) by the bacterial flora of food animals with no history of cefotaxime antibiotic exposure. A better understanding of the origin and transmission of resistance genes in these pre-harvest settings will be critical to development of strategies to prevent the spread of antimicrobial resistant microorganisms to hospitals and communities.
authors.affiliation: Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America.|Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Raies A
authors.initials: RA
authors.lastname: Mir
authors.affiliation: Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America.|Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, United States of America.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Weppelmann
authors.affiliation: Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America.|Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, United States of America.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Johnson
authors.affiliation: Food Science and Human Nutrition Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Douglas
authors.initials: D
authors.lastname: Archer
authors.affiliation: Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America.
authors.forename: J Glenn
authors.initials: JG
authors.lastname: Morris
authors.affiliation: Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America.|Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America.
authors.forename: KwangCheol Casey
authors.initials: KC
authors.lastname: Jeong
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D002439:Cefotaxime / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial
chemical_list: D000900:Anti-Bacterial Agents; D002439:Cefotaxime