Extended-Spectrum Beta-Lactamases

The definition of extended-spectrum beta-lactamases (ESBLs) hasexpanded rapidly, in terms of both the number and the variety ofenzymes. Bacteria bearing plasmidic ESBLs are spreading widelythroughout the world. In Canada, the problem has grown less rapidlythan in other parts of the world; however, ESBLs still present a significantimpediment to the treatment of serious infections with extendedspectrumcephalosporins and penicillins. Although SHV-derivedenzymes were the primary concern in the late 1980s and early 1990s,these enzymes have been rapidly overtaken by the CTX-M family ofESBLs. There is no reason to believe that the problem of ESBLs willnot expand rapidly in the face of intense antimicrobial pressure andlapses in infection control practices. Control should focus on earlydetection, accurate characterization, effective treatment and measuresto prevent further spread