beta-Lactamases: quality and resistance.

beta-Lactamase-mediated resistance to beta-lactam antibiotics is a feature of great clinical significance. beta-Lactamases are a diverse group of bacterial enzymes that vary in their abilities to hydrolyze beta-lactam antibiotics. beta-Lactamases possess an active site containing either a serine moiety or a zinc atom; serine beta-lactamases are currently of greater clinical prevalence. This review considers the molecular classification of beta-lactamases, the structure of the serine beta-lactamase active site and the mechanisms by which beta-lactamase production may become derepressed. The spread of beta-lactamases in the clinical setting and some important structural mutations that have extended the hydrolysis profiles of serine beta-lactamases are also discussed.