title: The spread of CTX-M-type extended-spectrum beta-lactamases.
abstract: CTX-M-type enzymes are a group of class A extended-spectrum beta-lactamases (ESBLs) that are rapidly spreading among Enterobacteriaceae worldwide. More that 50 allotypes are known, clustered into six sub-lineages. The CTX-M-encoding genes have been captured from the chromosome of Kluyvera spp. on conjugative plasmids that mediate their dissemination among pathogenic enterobacteria. CTX-M-type ESBLs exhibit powerful activity against cefotaxime and ceftriaxone but generally not against ceftazidime, which has important implications for laboratory detection. However, several CTX-M variants with enhanced ceftazidimase activity have been detected. The rapid and massive spread of CTX-M-type ESBLs is rapidly changing the ESBL epidemiology and, in some geographical areas, these enzymes are now the most prevalent ESBLs in Enterobacteriaceae.
authors.affiliation: Dipartimento di Biologia Molecolare, Sezione di Microbiologia, Università di Siena, Siena, Italy. rossolini@unisi.it
authors.forename: G M
authors.initials: GM
authors.lastname: Rossolini
authors.forename: M M
authors.initials: MM
authors.lastname: D'Andrea
authors.forename: C
authors.initials: C
authors.lastname: Mugnaioli
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D002439:Cefotaxime / Q000378:metabolism / Q000494:pharmacology; D002442:Ceftazidime / Q000378:metabolism / Q000494:pharmacology; D002443:Ceftriaxone / Q000378:metabolism / Q000494:pharmacology; D002511:Cephalosporins / Q000378:metabolism / Q000494:pharmacology*; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D008958:Models, Molecular; D015995:Prevalence; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D002443:Ceftriaxone; D002442:Ceftazidime; D001618:beta-Lactamases; D002439:Cefotaxime