title: Prevalence and mechanism of antimicrobial resistance in Staphylococcus aureus isolates from diseased cattle, swine and chickens in Japan.
abstract: Antimicrobial administration is essential for the control and treatment of diseases in animals, but the emergence and prevalence of antimicrobial-resistant Staphylococcus aureus is a significant concern during animal production. Here we investigated the antimicrobial susceptibility of S. aureus from diseased food-producing animals and molecularly characterized the methicillin-resistant and fluoroquinolone-resistant isolates. A total of 290 S. aureus isolates obtained from cattle (n=246), swine (n=16), and chickens (n=28) between 2003 and 2009 were examined for antimicrobial susceptibility against 9 antimicrobials using an agar dilution method. Resistance to penicillin (PC) was most frequently found (24.8%), followed by oxytetracycline (OTC, 10.0%), dihydrostreptomycin (4.1%), erythromycin (EM, 3.1%), enrofloxacin (ERFX, 2.1%), and kanamycin (1.7%). The PC resistance rate was significantly higher in swine than in cattle (P<0.01) and chickens (P<0.01). The resistance rates to OTC, EM and ERFX were significantly higher in swine and chickens than in cattle (P<0.05). Methicillin-resistant S. aureus (MRSA) was recovered from milk derived from a cow with mastitis in 2003; sequence type 8, SCCmec type IV and spa type t024. In the six ERFX-resistant strains isolated after 2003, amino acid substitutions in ParC with/without GyrA were detected. As the prevalence of MRSA and FQ-resistant S. aureus in the animals should be noticed, continuous monitoring is necessary to control resistance to clinically important antimicrobials in S. aureus from food-producing animals.
authors.affiliation: National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Baba
authors.forename: Kanako
authors.initials: K
authors.lastname: Ishihara
authors.forename: Manao
authors.initials: M
authors.lastname: Ozawa
authors.forename: Masaru
authors.initials: M
authors.lastname: Usui
authors.forename: Mototaka
authors.initials: M
authors.lastname: Hiki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tamura
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Asai
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology*; D002645:Chickens; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D007564:Japan / Q000453:epidemiology; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins