title: Antimicrobial drug use and antimicrobial resistance in enteric bacteria among cattle from Alberta feedlots.
abstract: The purpose of this study was to determine whether antimicrobial resistance (AMR) in foodborne pathogens (Escherichia coli O157, Salmonella, and Campylobacter) and non-type-specific E. coli obtained from fecal samples of feedlot cattle was associated with antimicrobial drug (AMD) use. A secondary objective was to determine if AMR in non-type-specific E. coli could be used as a predictor of AMR in foodborne pathogens. Fecal samples were collected from pen floors in 21 Alberta feedlots during March through December 2004, and resistance prevalence was estimated by season (Spring, Fall) and cattle type (fewest days-on-feed and closest to slaughter). AMD exposures were obtained by calculating therapeutic animal daily doses for each drug before sampling from feedlot records. Generalized linear mixed models were used to investigate the relationship between each AMR and AMD use. Non-type-specific E. coli was commonly recovered from fecal samples (88.62%), and the highest prevalence of resistance was found toward tetracycline (53%), streptomycin (28%), and sulfadiazine (48%). Campylobacter jejuni was recovered from 55.3% of the fecal samples, and resistance was generally less for the drugs that were evaluated (doxycycline 38.1%, ciprofloxacin 2.6%, nalidixic acid 1.64%, erythromycin 1.2%). E. coli O157 and Salmonella were recovered much less frequently (7% and 1% prevalence, respectively). The prevalence of recovery for the bacteria studied varied between seasons and cattle types, as did patterns of AMR. Among non-type-specific E. coli, resistance to tetracycline, streptomycin, and sulfadiazine was found to be positively associated with in-feed exposure as well as injectable tetracycline, but these differences were relatively small and of questionable practical relevance. Among C. jejuni isolates, cattle type was significantly associated with doxycycline resistance. Results suggested that resistance in non-type-specific E. coli to chloramphenicol, trimethoprim/sulfamethoxazole, and tetracycline might be used as predictors of resistance to these drugs in E. coli O157 recovered from the same fecal samples.
authors: Animal Population Health Institute, Colorado State University, Fort Collins, Colorado, USA.
authors: Sangeeta
authors: S
authors: Rao
authors: Joyce
authors: J
authors: Van Donkersgoed
authors: Valerie
authors: V
authors: Bohaychuk
authors: Thomas
authors: T
authors: Besser
authors: Xin-Ming
authors: XM
authors: Song
authors: Bruce
authors: B
authors: Wagner
authors: Dale
authors: D
authors: Hancock
authors: David
authors: D
authors: Renter
authors: David
authors: D
authors: Dargatz
authors: Paul S
authors: PS
authors: Morley
mesh_terms: D000416:Alberta; D000822:Animal Husbandry / Q000379:methods / Q000706:statistics & numerical data; D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage*; D016123:Campylobacter jejuni / Q000187:drug effects; D002417:Cattle; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000302:isolation & purification / Q000472:pathogenicity; D004926:Escherichia coli / Q000187:drug effects; D019453:Escherichia coli O157 / Q000187:drug effects; D005243:Feces / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D015233:Models, Statistical; D019779:Salmonella enterica / Q000187:drug effects; D012621:Seasons
chemical_list: D000890:Anti-Infective Agents