Limited transmission of bla(CTX-M-9)-type-positive Escherichia coli between humans and poultry in Vietnam.

We examined whether Escherichia coli isolates that produce CTX-M-9-type extended-spectrum ß-lactamases (ESBL) are transferred between humans and chickens in a Vietnamese community. The phylogenetic group compositions, sequence types, antimicrobial resistance profiles, the prevalence of plasmid antibiotic resistance genes, and the plasmid replicon types generally differed between the human and chicken E. coli isolates. Our results suggest that transmission of the bla(CTX-M-9)-positive E. coli between humans and poultry was limited.