Addressing the challenge of extended-spectrum beta-lactamases.

During the last decade, community-acquired extended-spectrum beta-lactamase (ESBL)-producing bacteria, and in particular Escherichia coli producing ESBLs of the CTX-M-type, have spread worldwide. These organisms are most often isolated from the urinary tract, but have also been isolated from bacteria in the blood. Cephalosporin- and fluoroquinolone-containing treatments are the two most common risk factors identified in patients with ESBL producers. In addition, associated resistance to other classes of antimicrobial agents are often observed in CTX-M producers, limiting the availability of therapeutic options. Carbapenems should be considered as the drug of choice for treating serious systemic infections caused by ESBL-producing bacteria, but preventing the spread of and appropriately managing these infections remains difficult.