Rodriguez-Baño, JesusPaterson, David L.2012-06-112012-06-112006-04-01Rodriguez-Baño J, Paterson DL. A Change in the Epidemiology of Infections Due to Extended-Spectrum b-Lactamase–Producing Organisms. Clin Infect Dis. (2006) 42 (7): 935-9371058-4838http://hdl.handle.net/10668/403Extended-spectrum β-lactamases (ESBLs) form a heterogeneous group that share the property of hydrolytic activity against the oxyimino-β-lactams while remaining susceptible to inhibition by β-lactamase inhibitors, such as clavulanic acid. From a clinical point of view, they are important because they confer resistance to penicillins, aztreonam, and cephalosporins, and ESBL-producing organisms are typically also resistant to aminoglycosides, trimethoprim-sulfamethoxazole, and quinolones [1]. Until recently, the main problem posed by ESBLs was related to nosocomial outbreaks caused by ESBL-producing Klebsiella species. These outbreaks are usually clonal, the strains are mainly spread through cross-transmission, and the risk factors are similar to those found for other multidrug-resistant nosocomial pathogens [2]. In Europe and the United States, most ESBL-producing Klebsiella isolates harbored enzymes belonging to the TEM and SHV families [3]. Detection of colonized patients by performing surveillance cultures within affected units, isolation precautions for colonized patients, and restriction of oxyimino-β-lactam use are frequently useful for the control of these outbreaks [1]. There is no evidence that hospital-acquired ESBL-producing klebsiellae are decreasing in importance—in fact, data from the Centers for Disease Control and Prevention show that 20.6% of Klebsiella pneumoniae isolates from United States intensive care units in 2003 were probable producers of ESBL [4]. This represented a 47% increase, compared with the preceding 5 years. However, during the last few years, an impressive increase in the number of ESBL-producing Escherichia coli (and, less frequently, other Enterobacteriaceae) is being described in several parts of the world [5–8]. This emergent phenomenon shows some differences from the problem posed by Klebsiella species; many of these ESBL-producing E. coli are isolated …enepidemiologybeta-lactamaseepidemiologiabeta-lactamasesMedical Subject Headings::Diseases::Bacterial Infections and Mycoses::Bacterial Infections::BacteremiaMedical Subject Headings::Diseases::Bacterial Infections and Mycoses::Infection::Cross InfectionMedical Subject Headings::Organisms::Bacteria::Gram-Negative Bacteria::Gram-Negative Facultatively Anaerobic Rods::EnterobacteriaceaeMedical Subject Headings::Diseases::Bacterial Infections and Mycoses::Bacterial Infections::Gram-Negative Bacterial Infections::Enterobacteriaceae InfectionsMedical Subject Headings::Anatomy::Fluids and Secretions::FecesMedical Subject Headings::Organisms::Eukaryota::Animals::Chordata::Vertebrates::Mammals::Primates::Haplorhini::Catarrhini::Hominidae::HumansMedical Subject Headings::Chemicals and Drugs::Enzymes and Coenzymes::Enzymes::Hydrolases::Amidohydrolases::beta-Lactamaseseditorialopen access10.1086/500945