TEM- and SHV-derived extended-spectrum beta-lactamases: relationship between selection, structure and function.


The later-generation cephalosporins were developed to overcome beta-lactamases which conferred resistance to earlier beta-lactam drugs. Within two years of their clinical introduction, the ubiquitous TEM and SHV plasmid-encoded beta-lactamase genes underwent simple point mutations that changed key amino acids around the active site of the protein and… (More)