New beta-lactamases in gram-negative bacteria: diversity and impact on the selection of antimicrobial therapy.
Of the 340 discrete beta-lactamases that have been identified, the most important groups of enzymes that are continuing to proliferate include the plasmid-encoded cephalosporinases, the metallo-beta-lactamases, and the extended-spectrum beta-lactamases. Resistance to specific beta-lactam-containing antimicrobial agents frequently can be traced to a single beta-lactamase, but this task is becoming more difficult for the clinical microbiology laboratory. Other factors, such as multiple beta-lactamase production, transferable multidrug-resistance genes, alterations in outer-membrane porins, and possible antibiotic efflux, all may contribute to a resistance phenotype. Appreciation of these factors may help the physician make a more informed decision when choosing therapy to try to avoid selection of even more pathogenic strains.
The R. W. Johnson Pharmaceutical Research Institute, Raritan, NJ, 08869, USA. kbush@prius.jnj.com
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D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D006090:Gram-Negative Bacteria / Q000201:enzymology*; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy*; D006801:Humans; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics / Q000502:physiology*
D000900:Anti-Bacterial Agents; D001618:beta-Lactamases