title: IncN plasmids carrying bla CTX-M-1 in Escherichia coli isolates on a dairy farm.
abstract: The aim of the study was to compare the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli bovine isolates on a conventional dairy cattle farm with high consumption of parenteral and intramammary cephalosporins (farm A) and on an organic dairy farm with no cephalosporin use (farm B). ESBL-producing E. coli were isolated from rectal swabs and milk filters by selective cultivation on MacConkey agar with cefotaxime (2mg/l). ESBL genes were identified by polymerase chain reaction (PCR) and sequencing, and the genetic diversity of the isolates was determined by XbaI pulsed field gel electrophoresis (PFGE). Conjugative transfer, incompatibility group, and restriction fragment length polymorphism (RFLP) profiles of the ESBL-carrying plasmids were studied. Higher prevalence (39%, n(rectal samples in cows)=309) of CTX-M-1-producing E. coli isolates was found on farm A compared to farm B (<1%, n(rectal samples in cows)=154; 0%, n(rectal samples in calves)=46). Using PFGE, the isolates from farm A were divided into nine pulsotypes. In all ESBL-positive isolates, the bla(CTX-M-1) gene was carried on 40 kb IncN conjugative plasmids of three related HincII restriction profiles. Horizontal gene transfer through transmission of IncN plasmids harboring bla(CTX-M-1) as well as clonal dissemination of a particular clone seems to be involved in dissemination of CTX-M-1-producing E. coli isolates in cows on the farm using cephalosporins in treating bacterial infections. The study demonstrates a possible role of cephalosporin use in the widespread occurrence of CTX-M-1-producing E. coli on the conventional dairy cattle farm compared to the organic farm.
authors.affiliation: Department of Biology and Wildlife Diseases, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences, Brno, Palackeho 1-3, 612 42 Brno, Czech Republic. m.dolejska@centrum.cz
authors.forename: Monika
authors.initials: M
authors.lastname: Dolejska
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Jurcickova
authors.forename: Ivan
authors.initials: I
authors.lastname: Literak
authors.forename: Lucie
authors.initials: L
authors.lastname: Pokludova
authors.forename: Jiri
authors.initials: J
authors.lastname: Bures
authors.forename: Alfred
authors.initials: A
authors.lastname: Hera
authors.forename: Ludmila
authors.initials: L
authors.lastname: Kohoutova
authors.forename: Jiri
authors.initials: J
authors.lastname: Smola
authors.forename: Alois
authors.initials: A
authors.lastname: Cizek
mesh_terms: D000818:Animals; D002417:Cattle / Q000382:microbiology; D002418:Cattle Diseases / Q000382:microbiology*; D018550:Cephalosporin Resistance; D002511:Cephalosporins / Q000494:pharmacology; D018153:Czech Republic; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics; D005260:Female; D022761:Gene Transfer, Horizontal; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D002511:Cephalosporins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C055184:beta-lactamase TEM-3; D001618:beta-Lactamases