A perspective on the present contribution of beta-lactamases to bacterial resistance with particular reference to induction of beta-lactamase and its clinical significance.

Resistance of bacteria to beta-lactam antibiotics has become a serious problem in the past several decades. Virtually all Staphylococcus aureus, many Haemophilus influenzae, Branhamella catarrhalis, Neisseria gonorrhoeae, many Enterobacteriaceae, many Pseudomonas aeruginosa and Bacteroides species possess beta-lactamases which hydrolyze to varying degree penems, penams, carbapenems, cephems, cephamycins and monobactams. The most common plasmid-mediated beta-lactamase is the so-called TEM beta-lactamase (Richmond Sykes type IIIa) which exists in Haemophilus, Neisseria and many of the Enterobacteriaceae. Techniques to overcome this resistance have been the development of beta-lactamase stable compounds and of beta-lactamase inhibitors. However, inducible chromosomally mediated beta-lactamases in species such as Enterobacter, Pseudomonas, Citrobacter and some Serratia have become an increasing problem with more widespread use of beta-lactamase stable cephalosporins.