Redefining extended-spectrum beta-lactamases: balancing science and clinical need

Abstract

The current beta-lactamase classifications have reached a high level of complexity, making them less accessible to clinicians, infection control professionals, hospital management and politicians. From the clinical perspective, a revised comprehensible nomenclature scheme is therefore needed. The term extended-spectrum beta-lactamases (ESBLs) has reached a broader audience over time, but is currently restricted to functional class 2be/molecular class A, clavulanic acid inhibited enzymes with activity against extended-spectrum cephalosporins. The proposed new classification expands the definition of ESBL to other clinically important acquired beta-lactamases with activity against extended-spectrum cephalosporins and/or carbapenems. The classical class A ESBLs have been designated ESBLA in this classification, whereas plasmid-mediated AmpC and OXA-ESBLs are classed as miscellaneous ESBLs (ESBLM). Lastly, the carbapenemases have been designated ESBLCARBA, ESBLs with hydrolytic activity against carbapenems. We believe that this simplified classification may encourage new groups of healthcare professionals to engage in the effort to prevent the spread of acquired beta-lactamases.

Figure 1

Proposal for classification of class A ESBLs (ESBL_A), miscellaneous ESBLs (ESBL_M) and ESBLs with hydrolytic activity against carbapenems (ESBL_CARBA). ^aResistant to clavulanic acid inhibition. ^bOXA-48 producing isolates may appear susceptible to cephalosporins in vitro (P. Nordmann, personal communication).