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Home Topics Infectious Diseases Infections A-Z Extended-Spectrum Beta-Lactamases (ESBLs)

Extended-Spectrum Beta-Lactamases (ESBLs)

Detecting ESBLs with an Etest

Extended-Spectrum Beta-Lactamases (ESBLs) are enzymes that can be produced by bacteria making them resistant to cephalosporins e.g. cefuroxime, cefotaxime and ceftazidime - which are the most widely used antibiotics in many hospitals.


ESBLs were first described in the mid-1980s and during the 1990s were mostly found in Klebsiella species, mostly in hospitals and often in intensive care units treating the most vulnerable patients. Public Health England (PHE) monitors trends in the numbers of bacteria producing these enzymes. Until recently, the numbers of patients affected remained small and the problem showed little sign of growing.

However, a new class of ESBL (called CTX-M enzymes) has emerged and these have been widely detected among Escherichia coli ( E. coli) bacteria. These ESBL-producing E. coli are able to resist penicillins and cephalosporins and are found most often in urinary tract infections - though not simple cystitis. Of concern, they have been found in the community as well as in hospitals, but patients with 'community acquired' infections may have had previous contact with hospitals.

PHE has an active research programme on ESBLs and investigates the enzymes, their genetics and the organisms that produce them.