title: blaCTX-M-₁₅-carrying Escherichia coli and Salmonella isolates from livestock and food in Germany.
abstract: OBJECTIVE
  The characterization of CTX-M-₁₅ β-lactamase-producing Escherichia coli and Salmonella isolates originating mainly from German livestock and food.
  
  
  METHODS
  E. coli (526, mainly commensals) and Salmonella (151) non-human isolates resistant to third-generation cephalosporins, originating from routine and monitoring submissions (2003-12) to the Federal Institute for Risk Assessment and different national targeted studies (2011-12), were examined for the presence of blaCTX-M-₁₅ genes by PCR amplification/sequencing. Additional resistance and virulence genes were screened by DNA microarray and PCR amplification. E. coli isolates with blaCTX-M-₁₅ were characterized by phylogenetic grouping, PFGE and multilocus sequence typing (MLST). The blaCTX-M-15 plasmids were analysed by replicon typing, plasmid MLST, S1 nuclease PFGE and Southern blot hybridization experiments.
  
  
  RESULTS
  Twenty-one E. coli (livestock, food and a toy; 4.0%) and two Salmonella (horse and swine; 1.3%) isolates were CTX-M-₁₅ producers. E. coli isolates were mainly ascribed to three clonal lineages of sequence types ST678 (German outbreak with enteroaggregative Shiga-toxin-producing E. coli O104:H4; salmon, cucumber and a toy), ST410 (poultry, swine and cattle farms) and ST167/617 (swine farms and turkey meat). The blaCTX-M-₁₅ genes were located on IncI1 and multireplicon IncF plasmids or on the chromosome of E. coli ST410 isolates.
  
  
  CONCLUSIONS
  The prevalence of CTX-M-₁₅-producing isolates from non-human sources in Germany is still low. The blaCTX-M-₁₅ gene is, however, present in multidrug-resistant E. coli clones with pathogenic potential in livestock and food. The maintenance of the blaCTX-M-₁₅ gene due to chromosomal carriage is noteworthy. The possibility of an exchange of CTX-M-₁₅-producing isolates or plasmids between livestock and humans (in both directions) deserves continuous surveillance.
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany.
authors: Jennie
authors: J
authors: Fischer
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany Hospital Universitario Ramón y Cajal, Servicio de Microbiología, Madrid, Spain.
authors: Irene
authors: I
authors: Rodríguez
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany.
authors: Beatrice
authors: B
authors: Baumann
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universidad de Barcelona, Barcelona, Spain.
authors: Elisabeth
authors: E
authors: Guiral
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany.
authors: Lothar
authors: L
authors: Beutin
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany.
authors: Andreas
authors: A
authors: Schroeter
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany.
authors: Annemarie
authors: A
authors: Kaesbohrer
authors: Robert Koch Institute, FG13 Nosocomial Pathogens and Antimicrobial Resistance, Wernigerode, Germany.
authors: Yvonne
authors: Y
authors: Pfeifer
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany.
authors: Reiner
authors: R
authors: Helmuth
authors: Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany beatriz.guerra@bfr.bund.de.
authors: Beatriz
authors: B
authors: Guerra
mesh_terms: D000818:Animals; D002417:Cattle; D004926:Escherichia coli / Q000201:enzymology / Q000302:isolation & purification*; D005523:Food Supply / Q000592:standards*; D005858:Germany; D006736:Horses; D006801:Humans; D058751:Livestock / Q000382:microbiology*; D012475:Salmonella / Q000302:isolation & purification* / Q000378:metabolism; D013552:Swine; D001618:beta-Lactamases / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases
keywords: CTX-M; ESBLs; antimicrobial resistance; chromosomal encoded; plasmids