title: Molecular characteristics of extended-spectrum β-lactamases in clinical isolates from Escherichia coli at a Japanese tertiary hospital.
abstract: The prevalence of ESBL has been increasing worldwide. In this study, we investigated the molecular characteristics of ESBL among clinical isolates of Escherichia coli from a Japanese tertiary hospital. A total of 71 consecutive and nonduplicate clinical isolates of ESBL-positive E. coli collected at Tohoku University Hospital between January 2008 and March 2011 were studied. The antimicrobial susceptibility profile of these strains was determined. PCR and sequencing were performed to identify genes for β-lactamase (bla(TEM), bla(SHV), bla(OXA-1-like), and bla(CTX-M)) and plasmid-mediated quinolone resistance determinants (PMQR). The isolates were also analyzed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Of the 71 strains, 68 were positive for CTX-M, 28 were positive for TEM, four were positive for OXA-1, and one was positive for SHV. Sequencing revealed that CTX-M-14 was the most prevalent (31/71), followed by CTX-M-27 (21/71) and then CTX-M-15 (9/71). Of the 28 TEM-positive strains, one was TEM-10 and the rest were TEM-1. One SHV-positive strain was SHV-12. The 21 CTX-M-27-producing isolates were divided into 14 unique PFGE types, while the 9 CTX-M-15 producers were divided into 8 types. Based on MLST, 9 CTX-M-14 procedures, 19 CTX-M-27 procedures, and 8 CTX-M-15 producers belonged to ST131. Thirty-five (94.6%) of the 37 ST131 E. coli strains showed resistance to levofloxacin, which was a higher rate than among non-ST131 strains (63.6%). Among ESBL-producing isolates, one, two, and six possessed qnrB, qnrS, qepA, and aac(6')-Ib-cr, respectively. Of the 6 isolates with aac(6')-Ib-cr, 4 carried the CTX-M-15 gene. Our data suggest that CTX-M-15-producing E. coli ST131 has emerged as a worldwide pandemic clone, while CTX-M-27 (a variant of CTX-M-14) is also spreading among E. coli ST131 in Japan.
authors.affiliation: Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan. yanohisa@med.tohoku.ac.jp
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Yano
authors.forename: Mina
authors.initials: M
authors.lastname: Uemura
authors.forename: Shiro
authors.initials: S
authors.lastname: Endo
authors.forename: Hajime
authors.initials: H
authors.lastname: Kanamori
authors.forename: Shinya
authors.initials: S
authors.lastname: Inomata
authors.forename: Risako
authors.initials: R
authors.lastname: Kakuta
authors.forename: Sadahiro
authors.initials: S
authors.lastname: Ichimura
authors.forename: Miho
authors.initials: M
authors.lastname: Ogawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shimojima
authors.forename: Noriomi
authors.initials: N
authors.lastname: Ishibashi
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Aoyagi
authors.forename: Masumitsu
authors.initials: M
authors.lastname: Hatta
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Gu
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yamada
authors.forename: Koichi
authors.initials: K
authors.lastname: Tokuda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kunishima
authors.forename: Miho
authors.initials: M
authors.lastname: Kitagawa
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Hirakata
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kaku
mesh_terms: D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D007564:Japan; D008826:Microbial Sensitivity Tests; D062606:Tertiary Care Centers; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases