Clinical significance of extended-spectrum beta-lactamases.

The spread of extended-spectrum beta-lactamases (ESBLs) in nosocomial and community-acquired enterobacteria is an important challenge for clinicians as the therapeutic options for these organisms are limited. The emergence of ESBL-producing Escherichia coli in the community, associated with the spread of CTX-M ESBL, is one of the most significant epidemiologic changes in infectious diseases during recent years. The epidemiology of these infections is complex and combines the expansion of mobile genetic elements with clonal spread. Infections caused by ESBL producers are associated with increased mortality, length of stay and increased cost. An inadequate empirical therapy for serious infections caused by these organisms is independently associated with increased mortality. Carbapenems are the drugs of choice for serious infections caused by ESBL-producing organisms but their overuse is a cause of concern.