Detection of chromosomal blaCTX-M-2 in diverse Escherichia coli isolates from healthy broiler chickens

The rise of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in food-producing animals is a growing concern for public health. We investigated ESBL producers isolated from broiler chickens in Brazil and characterized 19 CTX-M-2-producing E.coli. The ISCR1 was detected upstream of the chromosome-located gene bla(CTX-M-2), associated with sul-1 type integron structure. CTX-M-2-producing E.coli exhibited different PFGE-types and phylogenetic groups, showing a non-clonal dissemination. The sequence types found (ST93, ST155 and ST2309) have been associated with humans and animals worldwide. Herein, we report the chromosomal location of bla(CTX-M-2) on E.coli, highlighting the risks of multidrug-resistant bacteria in food-producing animals.