New developments in bacterial resistance mediated by beta-lactamases

Bacteria may resist the action of beta-lactam antibiotics by several mechanisms. Production of beta-lactamase is by far the most commonly encountered mechanism. Despite the fact that there are beta-lactam compounds that resist hydrolysis by beta-lactamases, certain gram-negative bacteria rapidly develop resistance to these agents. This resistance has been shown to be due to derepression of chromosomal Class I beta-lactamases. Emergence of resistance during therapy with the newer beta-lactams has become a significant problem in nosocomial infections. The indiscriminate use of expanded-spectrum beta-lactams should be avoided to minimize the therapeutic problems posed by this resistance as well as the ecological impact of broad-spectrum beta-lactam resistance on the hospital environment.