Importance of beta-lactamases and clinical implications of their inhibitors.

The production of beta-lactamases has constituted the main line of defence of bacteria exposed to beta-lactam antibiotics. beta-Lactamases may be part of the natural constitution of the cell, acquired by DNA transferred from other bacteria or induced by exposure to a beta-lactam antibiotic. Many different types of beta-lactamases have been described in a variety of bacteria.