Molecular characteristics of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae causing intra-abdominal infections from 9 tertiary hospitals in China.

•The most common ESBL type of E.coli causing IAIs in China was CTX-M-15.•SHV-2a was the most common ESBL type of K. pneumoniae causing IAIs in China.•The carbapenems remain the most active antimicrobial agents in vitro overall.•Continued monitoring of the antibiotics susceptibility is crucial.