title: Molecular and clinical characterization of plasmid-mediated AmpC β-lactamase-producing Escherichia coli bacteraemia: a comparison with extended-spectrum β-lactamase-producing and non-resistant E. coli bacteraemia.
abstract: Plasmid-mediated AmpC β-lactamase-producing Escherichia coli (AmpC-E) bacteraemia was characterized by comparison with bacteraemia caused by extended-spectrum β-lactamase (ESBL)-producing E. coli (ESBL-E) and non-resistant E. coli (NR-E) in the era of the worldwide spread of the CTX-M-15-producing O25b-ST131-B2 clone. Of 706 bloodstream E. coli isolates collected between 2005 and 2010 in three Japanese university hospitals, 111 ESBL screening-positive isolates were analysed for AmpC and ESBL genes by PCR. A case-control study was performed in which the cases consisted of all of the patients with AmpC-E bacteraemia. Phylogenetic groups, sequence types and O25b serotype were determined. Twenty-seven AmpC-E isolates (26 of which were of the CMY-2 type) were identified, and 54 ESBL-E and 54 NR-E isolates were selected for the controls. Nineteen AmpC-E isolates were also positive for ESBL. CTX-M-14 was the most prevalent ESBL type among both the AmpC-E and ESBL-E isolates. The O25b-ST131-B2 clone was the most prevalent among the ESBL-E isolates (26%) and the second most prevalent among the NR-E isolates (13%), but only one O25b-ST131-B2 clone was found among the AmpC-E isolates. Twenty-three different sequence types were identified among the AmpC-E isolates. When compared with bacteraemia with ESBL-E, previous isolation of multidrug-resistant bacteria and intravascular catheterization were independently associated with a lower risk for AmpC-E. When compared with NR-E bacteraemia, prior use of antibiotics was the only significant risk factor for AmpC-E. Unlike the spread of the O25b-ST131-B2 clone between ESBL-E and NR-E, the AmpC-E isolates were not dominated by any specific clone.
authors.affiliation: Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, Japan. yazblood@kuhp.kyoto-u.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumura
authors.forename: M
authors.initials: M
authors.lastname: Nagao
authors.forename: M
authors.initials: M
authors.lastname: Iguchi
authors.forename: T
authors.initials: T
authors.lastname: Yagi
authors.forename: T
authors.initials: T
authors.lastname: Komori
authors.forename: N
authors.initials: N
authors.lastname: Fujita
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: A
authors.initials: A
authors.lastname: Matsushima
authors.forename: S
authors.initials: S
authors.lastname: Takakura
authors.forename: S
authors.initials: S
authors.lastname: Ichiyama
mesh_terms: D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology*; D016022:Case-Control Studies; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000145:classification* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology*; D005260:Female; D005838:Genotype; D006785:Hospitals, University; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D058889:Molecular Typing; D010802:Phylogeny; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D001618:beta-Lactamases