title: Antimicrobial-Resistant Fecal Bacteria from Ceftiofur-Treated and Nonantimicrobial-Treated Comingled Beef Cows at a Cow-Calf Operation.
abstract: We compared the occurrences of 3rd-generation cephalosporin-resistant (3GCr), tetracycline-resistant (TETr), and trimethoprim-sulfamethoxazole-resistant (COTr) Escherichia coli, 3GCrand nalidixic acid-resistant (NALr) Salmonella enterica, and erythromycin-resistant (ERYr) enterococci from the fecal samples of ceftiofur-treated (n = 162) and nonantimicrobial-treated (n = 207) comingled beef cows ≥8 years old, for which complete antimicrobial treatment records were available. The prevalence of 3GCr(17%; n = 369), TETr(88%), COTrE. coli (22%), and ERYrenterococci (69%) was not significantly (p > 0.05) associated with ceftiofur treatment, prior history of other antimicrobial treatments, or duration of time between last antimicrobial treatment and sampling. 3GCrand NALrS. enterica were not detected. The prevalence of tetB was significantly (p < 0.05) higher compared with tetA among TETrE. coli. However, the prevalence of tetA was significantly (p < 0.05) higher than tetB among 3GCrand COTrE. coli. There was a significant (p < 0.05) association between tetM and ermB among ERYrenterococci. In conclusion, occurrences of 3GCr, TETr, and COTrE. coli and ERYrenterococci in comingled antimicrobial-treated and nonantimicrobial-treated beef cows were not associated with ceftiofur or other antimicrobial use, indicating that other factors influenced the observed levels of antimicrobial-resistant bacteria in feces of beef cows.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center , Clay Center, Nebraska.
authors.forename: Getahun E
authors.initials: GE
authors.lastname: Agga
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center , Clay Center, Nebraska.
authors.forename: John W
authors.initials: JW
authors.lastname: Schmidt
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center , Clay Center, Nebraska.
authors.forename: Terrance M
authors.initials: TM
authors.lastname: Arthur
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000382:microbiology*; D018550:Cephalosporin Resistance / Q000235:genetics*; D002511:Cephalosporins / Q000494:pharmacology; D060085:Coinfection / Q000188:drug therapy / Q000382:microbiology; D003430:Cross-Sectional Studies; D016983:Enterococcus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D005260:Female; D015870:Gene Expression; D005798:Genes, Bacterial; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000382:microbiology; D009329:Nebraska; D012481:Salmonella Infections, Animal / Q000188:drug therapy / Q000382:microbiology; D019779:Salmonella enterica / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; C053503:ceftiofur
keywords: E. coli; Salmonella; antimicrobial resistance; beef cows; ceftiofur; cephalosporin; enterococcus