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J Antimicrob Chemother. 2014 Nov;69(11):2951-8. doi: 10.1093/jac/dku270. Epub 2014 Jul 28.

blaCTX-M-₁₅-carrying Escherichia coli and Salmonella isolates from livestock and food in Germany.

Author information

1
Federal Institute for Risk Assessment, National Reference Laboratory for Antimicrobial Resistance, Department Biological Safety, Max-Dohrn Straße 8-10, D-10589 Berlin, Germany.
2
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.
3
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.
4
Robert Koch Institute, FG13 Nosocomial Pathogens and Antimicrobial Resistance, Wernigerode, Germany.
5
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.

Abstract

OBJECTIVES:

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.

KEYWORDS:

CTX-M; ESBLs; antimicrobial resistance; chromosomal encoded; plasmids

PMID:
25074857
DOI:
10.1093/jac/dku270
[Indexed for MEDLINE]

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