title: Antimicrobial susceptibility of Arcanobacterium pyogenes isolated from cattle and pigs.
abstract: The minimum inhibitory concentrations (MICs) of 18 antimicrobial agents were determined for 49 Arcanobacterium pyogenes isolates (42 bovine isolates and 7 porcine isolates). Benzylpenicillin and ampicillin were the most active antibiotics, with MIC ranges of < or = 0.0125-0.05 microgram/ml for both bovine and porcine isolates. All isolates were susceptible to penicillins and cephems. MICs for 90% of the isolates of dihydrostreptomycin, gentamicin and oxytetracycline for bovine isolates were > 100 micrograms/ml, 1.56 micrograms/ml and 25 micrograms/ml, respectively. More resistance to dihydrostreptomycin appeared among porcine isolates (85.7%) than among bovine isolates (52.4%). Resistance to gentamicin occurred in only 3 (7.1%) of the bovine isolates. Resistance to oxytetracycline also appeared more frequent among porcine isolates (85.7%) than among bovine isolates (57.1%). All bovine isolates were susceptible to erythromycin, tilmocosin and lincomycin, but two porcine isolates (28.6%) were simultaneously resistant to these antibiotics. Tiamulin was as active as tilmicosin, with an MIC for 50% of the isolates (MIC50) of 0.05 microgram/ml for both bovine and porcine isolates. The MIC50s of chloramphenicol and its derivatives florfenicol and thiamphenicol were all 1.56 micrograms/ml. The fluoroquinolones enrofloxacin and ofloxacin were not so active as penicillins and macrolides, with MIC50s of 0.78 microgram/ml and 1.56 micrograms/ml, respectively, for both bovine and porcine isolates.
authors.affiliation: National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yoshimura
authors.forename: A
authors.initials: A
authors.lastname: Kojima
authors.forename: M
authors.initials: M
authors.lastname: Ishimaru
mesh_terms: D000191:Actinomycetaceae / Q000187:drug effects*; D000196:Actinomycosis / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D000617:Aminoglycosides; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000382:microbiology*; D002511:Cephalosporins / Q000494:pharmacology / Q000627:therapeutic use; D002701:Chloramphenicol / Q000494:pharmacology / Q000627:therapeutic use; D004352:Drug Resistance, Microbial; D024841:Fluoroquinolones; D018942:Macrolides; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology / Q000627:therapeutic use; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy / Q000382:microbiology*; D013754:Tetracyclines
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D024841:Fluoroquinolones; D018942:Macrolides; D010406:Penicillins; D013754:Tetracyclines; D002701:Chloramphenicol