title: Herd prevalence of Enterobacteriaceae producing CTX-M-type and CMY-2 β-lactamases among Japanese dairy farms.
abstract: OBJECTIVE
  To determine the herd prevalence of Enterobacteriaceae producing CTX-M-type extended-spectrum β-lactamases (ESBLs) among 381 dairy farms in Japan.
  
  
  RESULTS
  Between 2007 and 2009, we screened 897 faecal samples using BTB lactose agar plates containing cefotaxime (2 μg ml(-1)). Positive isolates were tested using ESBL confirmatory tests, PCR and sequencing for CTX-M, AmpC, TEM and SHV. The incidence of Enterobacteriaceae producing CTX-M-15 (n = 7), CTX-M-2 (n = 12), CTX-M-14 (n = 3), CMY-2 (n = 2) or CTX-M-15/2/14 and CMY-2 (n = 4) in bovine faeces was 28/897 (3·1%) faecal samples. These genes had spread to Escherichia coli (n = 23) and three genera of Enterobacteriaceae (n = 5). Herd prevalence was found to be 20/381 (5·2%) dairy farms. The 23 E. coli isolates showed clonal diversity, as assessed by multilocus sequence typing and pulsed-field gel electrophoresis. The pandemic E. coli strain ST131 producing CTX-M-15 or CTX-M-27 was not detected.
  
  
  CONCLUSIONS
  Three clusters of CTX-M (CTX-M-15, CTX-M-2, CTX-M-14) had spread among Japanese dairy farms.
  
  
  CONCLUSIONS
  This is the first report on the prevalence of multidrug-resistant CTX-M-15-producing E. coli among Japanese dairy farms.
authors.affiliation: Veterinary Clinical Laboratory, Nemuro District Agricultural Mutual Aid Association, Nakashibetsu, Hokkaido, Japan. monishi@kind.ocn.ne.jp
authors.forename: M
authors.initials: M
authors.lastname: Ohnishi
authors.forename: A T
authors.initials: AT
authors.lastname: Okatani
authors.forename: H
authors.initials: H
authors.lastname: Esaki
authors.forename: K
authors.initials: K
authors.lastname: Harada
authors.forename: T
authors.initials: T
authors.lastname: Sawada
authors.forename: M
authors.initials: M
authors.lastname: Murakami
authors.forename: K
authors.initials: K
authors.lastname: Marumo
authors.forename: Y
authors.initials: Y
authors.lastname: Kato
authors.forename: R
authors.initials: R
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Shimura
authors.forename: N
authors.initials: N
authors.lastname: Hatanaka
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002417:Cattle / Q000382:microbiology*; D003612:Dairying; D016521:Electrophoresis, Gel, Pulsed-Field; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification; D004926:Escherichia coli / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D007564:Japan; D058885:Multilocus Sequence Typing; D001618:beta-Lactamases / Q000032:analysis*
chemical_list: D000900:Anti-Bacterial Agents; C103022:beta-lactamase CMY-2; C071167:beta-lactamase CTX-2; D001618:beta-Lactamases