title: Molecular characterization of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella spp. isolates in Mongolia.
abstract: OBJECTIVE
  The aim of this study was to determine the molecular characteristics of β-lactamase genes in extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae isolates from Mongolia.
  
  
  METHODS
  Fifty-six ESBL-producing Enterobacteriaceae isolates were collected, of which 46 were Escherichia coli, seven were Klebsiella pneumoniae, and three were K. oxytoca. Minimum inhibitory concentrations for selected antibiotics were tested using the agar dilution method, and the β-lactamase genes were determined using polymerase chain reaction combined with sequencing. Pulsed-field gel electrophoresis (PFGE) was used for genotyping all isolates, and phylogenetic grouping was performed on ESBL-producing E. coli isolates. Conjugation tests combined with plasmid digestion assays were used to determine whether there was a horizontal spread in Mongolia.
  
  
  RESULTS
  Among the 56 ESBL-producing isolates, 43 isolates (76.8%) were resistant to fluoroquinolones, but all isolates were susceptible to carbapenems and amikacin. The polymerase chain reaction sequencing results showed that the dominant CTX-M genotype was CTX-M-15 (19/46, 41.3%) in the ESBL-producing E. coli isolates. By contrast, CTX-M-14 and CTX-M-3 were the major genotypes found in Klebsiella spp. Phylogenetic analysis revealed that 21 ESBL-producing E. coli isolates belonged to group D (21/46, 45.6%), followed by group A (13/46, 28.3%), group B2 (11/46, 23.9%), and group B1 (1/46, 2.2%). Only four E. coli isolates (4/46, 8.7%) belonged to the ST131 clone. PFGE showed that the ESBL-producing Enterobacteriaceae were genetically unrelated. The conjugation assay showed that two plasmids harboring CTX-M-15 in E. coli isolates were genetic unrelated, whereas seven plasmids harboring CTX-M-14 (5/7 and 2/7) and four plasmids harboring CTX-M-55 (4/4) showed genetic relatedness, indicating the dissemination of resistance plasmids in this area.
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Cheng-Yen
authors.initials: CY
authors.lastname: Kao
authors.affiliation: Department of Cellular Biology and Biochemistry, Mongolian National University of Medical Sciences, Mongolia.
authors.forename: Uuganbayar
authors.initials: U
authors.lastname: Udval
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Huang
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Hsiu-Mei
authors.initials: HM
authors.lastname: Wu
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Ay-Huey
authors.initials: AH
authors.lastname: Huang
authors.affiliation: Department of Cellular Biology and Biochemistry, Mongolian National University of Medical Sciences, Mongolia.
authors.forename: Enkhbaatar
authors.initials: E
authors.lastname: Bolormaa
authors.affiliation: Department of Pathology, National Cheng Kung University Hospital, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Jing-Jou
authors.initials: JJ
authors.lastname: Yan
authors.affiliation: Department of Cellular Biology and Biochemistry, Mongolian National University of Medical Sciences, Mongolia.
authors.forename: Zorig
authors.initials: Z
authors.lastname: Urangoo
authors.affiliation: Department of Cellular Biology and Biochemistry, Mongolian National University of Medical Sciences, Mongolia.
authors.forename: Gunchin
authors.initials: G
authors.lastname: Batbaatar
authors.affiliation: Department of Cellular Biology and Biochemistry, Mongolian National University of Medical Sciences, Mongolia. Electronic address: khosbayar.t@mnums.edu.mn.
authors.forename: Tulgaa
authors.initials: T
authors.lastname: Khosbayar
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Center of Infectious Disease and Signaling Research, College of Medicine, National Cheng Kung University, Tainan, Taiwan. Electronic address: jjwu@mail.ncku.edu.tw.
authors.forename: Jiunn-Jong
authors.initials: JJ
authors.lastname: Wu
mesh_terms: D000583:Amikacin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D015780:Carbapenems / Q000494:pharmacology; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy; D029968:Escherichia coli Proteins / Q000235:genetics*; D024841:Fluoroquinolones / Q000494:pharmacology; D006801:Humans; D007710:Klebsiella Infections / Q000188:drug therapy; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D008986:Mongolia; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D029968:Escherichia coli Proteins; D024841:Fluoroquinolones; D000583:Amikacin; C456080:beta-lactamase CTX-M-14; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases; C000602253:beta-lactamase CTX-M, E coli; C000602254:beta-lactamase CTX-M-55, E coli
keywords: CTX-M; Enterobacteriaceae; Extended-spectrum β-lactamase; PFGE; antibiotic resistance