[Identification and classification of beta-lactamases in clinical isolates of bacteria]

Emergence of bacterial resistance has rendered ineffective a number of previously valuable antibiotic treatments and now threatens the effectiveness of others. beta-Lactam resistance is no longer predominantly a hospital-treated problem; it has now become an important issue in community medicine. More than 100-beta-lactamases have been identified and classified according to their structure, substrate specificity, and whether they are chromosomal or plasmid-mediated. beta-Lactamase production is rare among Gram-positive pathogens, important exceptions being Staphylococcus aureus and Enterococcus faecalis. By contrast, many Gram-negative pathogens are beta-lactamase-positive; inducible and/or hyper-productive strains are particularly challenging in the clinical setting. Surveillance programs have shown that, in general, beta-lactam resistance is on the increase, and that the plasmid-mediated beta-lactamase have developed rapidly over past decade such as ESBLs and carbapenemases.