title: Bench-to-bedside review: The role of beta-lactamases in antibiotic-resistant Gram-negative infections.
abstract: Multidrug resistance has been increasing among Gram-negative bacteria and is strongly associated with the production of both chromosomal- and plasmid-encoded beta-lactamases, whose number now exceeds 890. Many of the newer enzymes exhibit broad-spectrum hydrolytic activity against most classes of beta-lactams. The most important plasmid-encoded beta-lactamases include (a) AmpC cephalosporinases produced in high quantities, (b) the expanding families of extended-spectrum beta-lactamases such as the CTX-M enzymes that can hydrolyze the advanced-spectrum cephalosporins and monobactams, and (c) carbapenemases from multiple molecular classes that are responsible for resistance to almost all beta-lactams, including the carbapenems. Important plasmid-encoded carbapenemases include (a) the KPC beta-lactamases originating in Klebsiella pneumoniae isolates and now appearing worldwide in pan-resistant Gram-negative pathogens and (b) metallo-beta-lactamases that are produced in organisms with other deleterious beta-lactamases, causing resistance to all beta-lactams except aztreonam. beta-Lactamase genes encoding these enzymes are often carried on plasmids that bear additional resistance determinants for other antibiotic classes. As a result, some infections caused by Gram-negative pathogens can now be treated with only a limited number, if any, antibiotics. Because multidrug resistance in Gram-negative bacteria is observed in both nosocomial and community isolates, eradication of these resistant strains is becoming more difficult.
authors.affiliation: Department of Biology, Indiana University, Jordan Hall A311, Bloomington, IN 47405, USA. karbush@indiana.edu
authors.forename: Karen
authors.initials: K
authors.lastname: Bush
mesh_terms: D024881:Drug Resistance, Bacterial; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006801:Humans; D001618:beta-Lactamases / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases