Klebsiella pneumoniae, a human-dog shuttle organism for the genes of CTX-M ESBL

Abstract Antimicrobials reserved for human medicines are permitted for companion animals and it is important to understand multidrug-resistant pathogens recovered from companion animals in terms of epidemiological correlation with human pathogens and possibility of transmission to human-beings. Seventeen of each CTX-M-type extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) and Klebsiella pneumoniae (ESBL-KP) canine isolates were assessed. Entire genomes of the 34 isolates were sequenced. Plasmid transfer and relative growth rates were assessed at differed temperature conditions indicating the body temperature of dogs, that of human-beings, and environment. ESBL-ECs were clonally diverse, while ESBL-KPs were not. The ESBL-ECs carried the bla CTX−M−15 gene in plasmids and the bla CTX−M−14-like gene either in chromosomes or in plasmids. The ESBL-KPs possessed the bla CTX−M−15 gene in plasmids (n = 15). One of the isolates carried another bla CTX−M−15 gene in a chromosome simultaneously and the other isolate had an additional bla CTX−M−9 gene-harbouring plasmid, together. Two ESBL-KP isolates carried the bla CTX−M−14 gene in plasmids. Plasmid transfer ESBL-EC to K. pneumoniae was efficient and the differed biological costs by temperature was much more in ESBL-EC than in ESBL-KP. Intersectoral dissemination of ESBL-ECs occurred mainly by horizontal gene transfer, while that of ESBL-KPs occurred by clonal dissemination.