Overview of the epidemiological profile and laboratory detection of extended-spectrum beta-lactamases.
Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated bacterial enzymes that confer resistance to a broad range of beta-lactams. They are descended by genetic mutation from native beta-lactamases found in gram-negative bacteria, especially infectious strains of Escherichia coli and Klebsiella species. Genetic sequence modifications have broadened the substrate specificity of the enzymes to include third-generation cephalosporins, such as ceftazidime. Because ESBL-producing strains are resistant to a wide variety of commonly used antimicrobials, their proliferation poses a serious global health concern that has complicated treatment strategies for a growing number of hospitalized patients. Another resistance mechanism, also common to Enterobacteriaceae, results from the overproduction of chromosomal or plasmid-derived AmpC beta-lactamases. These organisms share an antimicrobial resistance pattern similar to that of ESBL-producing organisms, with the prominent exception that, unlike most ESBLs, AmpC enzymes are not inhibited by clavulanate and similar beta-lactamase inhibitors. Recent technological improvements in testing and in the development of uniform standards for both ESBL detection and confirmatory testing promise to make accurate identification of ESBL-producing organisms more accessible to clinical laboratories.
Department of Pathology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA. michael-pfaller@uiowa.edu
Michael A
MA
Pfaller
John
J
Segreti
D004755:Enterobacteriaceae / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D004927:Escherichia coli Infections / Q000145:classification / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D007709:Klebsiella / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D007710:Klebsiella Infections / Q000145:classification / Q000453:epidemiology / Q000382:microbiology; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards*; D012307:Risk Factors; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*
D001618:beta-Lactamases