title: The first major extended-spectrum beta-lactamase outbreak in Scandinavia was caused by clonal spread of a multiresistant Klebsiella pneumoniae producing CTX-M-15.
abstract: Between May and December 2005, 64 multidrug-resistant isolates of Klebsiella pneumoniae were detected from patients admitted to Uppsala University Hospital. This represented a dramatic increase in ESBL-producing K. pneumoniae compared to previous years. To investigate the epidemiology and to characterize the resistance mechanisms of the isolates, a study was initiated. Antibiotic susceptibility was determined by means of the Etest and the disc diffusion method. Extended-spectrum beta-lactamase (ESBL) production was identified by clavulanic acid synergy test and confirmed with PCR amplification followed by DNA sequencing. DNA profiles of the isolates were examined with pulsed-field gel electrophoresis (PFGE). All isolates were resistant or exhibited reduced susceptibility to cefadroxil, cefuroxime, cefotaxime, ceftazidime, aztreonam, piperacillin/tazobactam, ciprofloxacin, tobramycin, and trimethoprim-sulfamethoxazole. They produced ESBL of the CTX-M-15 type, and the involvement of a single K. pneumoniae clone was shown. This is the first major clonal outbreak of multiresistant ESBL-producing K. pneumoniae in Scandinavia. The outbreak demonstrates the epidemic potential of enterobacteria containing ESBLs of the CTX-M type, even in a country with a relatively low selective pressure and a low prevalence of multiresistant bacteria.
authors.affiliation: Department of Clinical Microbiology, Uppsala University Hospital, Uppsala, Sweden. birgitta.lytsy@lul.se
authors.forename: Birgitta
authors.initials: B
authors.lastname: Lytsy
authors.forename: Linus
authors.initials: L
authors.lastname: Sandegren
authors.forename: Eva
authors.initials: E
authors.lastname: Tano
authors.forename: Erik
authors.initials: E
authors.lastname: Torell
authors.forename: Dan I
authors.initials: DI
authors.lastname: Andersson
authors.forename: Asa
authors.initials: A
authors.lastname: Melhus
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods; D019818:Clavulanic Acid; D004269:DNA, Bacterial / Q000235:genetics; D004196:Disease Outbreaks; D004352:Drug Resistance, Microbial; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology*; D007711:Klebsiella pneumoniae / Q000145:classification / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D013548:Sweden / Q000453:epidemiology; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D019818:Clavulanic Acid; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases