[Influence of beta-lactamases on bacterial resistance (author's transl)].

Several factors influence the antibacterial activity of beta-lactam antibiotics. Protection against attack by beta-lactam antibiotics can be provided by several mechanisms, e.g. the production of inactivating enzymes such as beta-lactamases. Gram-positive bacteria produce a penicillin-hydrolysing enzyme exhibiting only minor molecular variants; among gram-negative bacteria, however, there is a number of enzymes with various substrate profiles. Plasmid-mediated, species independent enzymes deserve special attention. The production of a beta-lactamase cannot be regarded as the sole determinant in resistance against beta-lactam antibiotics; moreover, it is the interaction with other mechanisms that provides protection against the attack of beta-lactam compounds. Above all, the ability of the antibiotic to penetrate the "outer membrane" at a sufficient rate to reach its target before being inactivated by beta-lactamases is especially important.