New β-Lactamases: A Paradigm for the Rapid Response of Bacterial Evolution in the Clinical Setting

Abstract

Production of β-lactamases is one of the most common mechanisms of bacterial resistance to β-lactam antibiotics. In the clinical setting, the introduction of new classes of β-lactams has invariably been followed by the emergence of new β-lactamases capable of degrading them, as a paradigmatic example of rapid bacterial evolution under a rapidly changing selective environment. The scope of this article is to provide an overview on the recent evolution of β-lactamase-mediated resistance among bacterial pathogens. Focus is on the mechanisms of evolution and dissemination of enzymes of greater clinical impact, including the extended-spectrum β-lactamases, the AmpC-type β-lactamases and the carbapenemases, which are currently responsible for emerging resistance to the most recent and powerful β-lactams (the expanded-spectrum cephalosporins and the carbapenems) among major Gram-negative pathogens such as Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter.

Keywords: :

• antimicrobial resistance
• β-lactam antibiotics
• β-lactamases
• β-lactam resistance
• carbapenemases
• evolution
• extended-spectrum β-lactamases
• Gram-negative bacteria