Infections with organisms producing extended-spectrum β-lactamase

Extended-spectrum β-lactamases (ESBL) are enzymes produced by a variety of Gram-negative bacilli, which confer reduced susceptibility to third-generation cephalosporins and aztreonam. Resistance to other antibiotic classes (such as aminoglycosides or fluoroquinolones) is also frequently observed in ESBL-producing organisms. Outbreaks of hospital-acquired infection with ESBL-producing organisms were recognized more than 20 years ago. Acquisition in nursing homes and other health care facilities was also noted. In more recent times, community-onset infections, sometimes in patients without health care contact, have been widely observed. The origins of community-acquired infection with ESBL-producing organisms is an area deserving much future study.