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J Antimicrob Chemother. 2010 Apr;65(4):651-60. doi: 10.1093/jac/dkq004. Epub 2010 Jan 29.

Emergence of human pandemic O25:H4-ST131 CTX-M-15 extended-spectrum-beta-lactamase-producing Escherichia coli among companion animals.

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Institute of Microbiology and Epizootics, Freie Universit├Ąt Berlin, Philippstr. 13, 10115 Berlin, Germany.



In view of the intercontinental emergence of Escherichia coli clone O25:H4-ST131 producing CTX-M-15 extended-spectrum beta-lactamase (ESBL) in human clinical settings it would be of great interest to explore its existence in animals to unravel a possible reservoir function and the origin and transmission of this group of multiresistant strains.


A total of 177 clinical phenotypically ESBL-producing E. coli isolates, mainly obtained from companion animals with urinary tract infections, wound infections and diarrhoea, were collected in a veterinary diagnostic laboratory covering a European-wide service area. They were screened for molecular subtype O25b and multilocus sequence type 131. O25b-ST131 isolates were subsequently tested for ESBL types, and phenotypic and genotypic resistance determinants. Further characterization of the strains was performed by PFGE and virulence gene typing.


Ten (5.6%) of 177 phenotypically ESBL-producing E. coli isolates, nine strains from dogs and one strain from a horse, were allocated to the B2-O25b-ST131 lineage. Nine of these isolates harboured a CTX-M-15-type beta-lactamase enzyme while one strain possessed an SHV-12-type ESBL. Macrorestriction analysis revealed a cluster formation of six of the animal CTX-M-15-type ESBL-producing strains from five different European countries together with a human control strain constituting a group of clonally related strains at a similarity value of 87.0%.


Our findings demonstrate that the group of clonally related human B2-O25:H4-ST131 CTX-M-15-type ESBL-producing E. coli strains is present in companion animals from various European countries. This highlights the possibility of inter-species transmission of these multiresistant strains from human to animal and vice versa.

[Indexed for MEDLINE]

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