A matched case-control study was performed to evaluate the risk factors for and outcomes of healthcare-associated infection due to extended-spectrum β-lactamase-producing Escherichia coli or extended-spectrum β-lactamase-producing Klebsiella pneumoniae in Thailand. By multivariable analysis, prior exposure to third-generation cephalosporins and transfer from another hospital were risk factors associated with infection. Receipt of inadequate antimicrobial therapy was a predictor of mortality.