title: Molecular and phenotypic characterization of Escherichia coli and Klebsiella pneumoniae producing extended-spectrum β-lactamases with focus on CTX-M in a low-endemic area in Sweden.
abstract: During the last decade increasing prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has been detected worldwide, mainly due to dissemination of Escherichia coli and Klebsiella pneumoniae producing CTX-M-type ESBLs. CTX-M-15 is the most widespread CTX-M type, and the predominant type in various countries. Dissemination of ESBL-producing organisms is caused not only by horizontal transfer of plasmids, but also by clonal spread of ESBL-producing strains. In this study, the molecular epidemiology of class A ESBL (ESBL(A))-producing E. coli and K. pneumoniae isolated in Örebro County, Sweden, was investigated. Out of 200 ESBL(A) -producing E. coli and K. pneumoniae isolates, collected over a 10-year period, 87% were producing CTX-M, belonging to subgroup CTX-M-1 (64%), CTX-M-9 (34%), or CTX-M-2 (2%). The remaining isolates were producing variants of SHV and TEM. Sequencing of the bla(CTX-M) genes revealed 10 different CTX-M types, with a dominance of CTX-M-15 (E. coli 54%, K. pneumoniae 50%) followed by CTX-M-14 (E. coli 28%, K. pneumoniae 27%). Phenotypic characterization of the CTX-M-producing isolates was performed using the PhenePlate system. Although a few minor clusters of CTX-M-15 and CTX-M-14 producers were identified, the majority of the isolates did not appear to be clonally related.
authors.affiliation: Departments of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Onnberg
authors.forename: Paula
authors.initials: P
authors.lastname: Mölling
authors.forename: Johanna
authors.initials: J
authors.lastname: Zimmermann
authors.forename: Bo
authors.initials: B
authors.lastname: Söderquist
mesh_terms: D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D019353:Endemic Diseases; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D005798:Genes, Bacterial; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D017720:Molecular Epidemiology; D010641:Phenotype; D010802:Phylogeny; D013548:Sweden / Q000453:epidemiology; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics*
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D001618:beta-Lactamases