title: Farm-level impact of therapeutic antimicrobial use on antimicrobial-resistant populations of Escherichia coli isolates from pigs.
abstract: We investigated the farm-level impact of the use of several different antimicrobial agents on the population of antimicrobial-resistant commensal bacteria of animal origin to appropriately assess the release risk of resistance. This study was carried out based on the results of a survey on the history of antimicrobial drug use in 297 pig farms and antimicrobial susceptibility testing for the 545 Escherichia coli isolates (one or two isolates/pig/farm). A comparative analysis with the nonexposed herd revealed that ampicillin (ABPC) resistance in E. coli increased in the herds that were exposed to penicillin (relative risk [RR], 1.75) and penicillin-streptomycin (RR, 2.28); dihydrostreptomycin (DSM) resistance, in the penicillin-streptomycin-exposed herd (RR, 1.75); and trimethoprim (TMP) resistance in the methoprim-sulfonamide-exposed herd (RR, 2.10). On the other hand, ABPC and DSM resistances increased in the tetracycline-exposed herd (RR, 1.66 and 1.58, respectively); TMP resistance, in the penicillin-exposed herd (RR, 1.77); and oxytetracycline and kanamycin resistances, in the penicillin-streptomycin-exposed herd (RR, 1.28 and 2.22, respectively). These results demonstrated that the development of cross-resistance and coresistance, imposed by the therapeutic use of the antimicrobials studied, contributed the farm-level prevalence of antimicrobial-resistant E. coli and that the influence of coselection was characteristic to individual antimicrobial agents used.
authors: National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan. harada@nval.go.jp
authors: Kazuki
authors: K
authors: Harada
authors: Tetsuo
authors: T
authors: Asai
authors: Manao
authors: M
authors: Ozawa
authors: Akemi
authors: A
authors: Kojima
authors: Toshio
authors: T
authors: Takahashi
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy* / Q000382:microbiology / Q000662:veterinary; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D015995:Prevalence; D012306:Risk; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents