title: Chromosomal cephalosporinase in Enterobacter hormaechei as an ancestor of ACT-1 plasmid-mediated AmpC β-lactamase.
abstract: In this study of the diversity of AmpC β-lactamase in clinical isolates of Enterobacter spp., a strain was found carrying the plasmid-mediated AmpC β-lactamase ACT-1 gene on its chromosome. The strain was identified as Enterobacter hormaechei using phylogenetic analysis of 16S rRNA and hsp60 genes. In addition, the species was confirmed by DNA-DNA hybridization. The genetic environment of the bla(ACT-1) gene was characterized, including the ampR and ampG genes, using a two-step PCR. The amino acid sequences of AmpR at serine 35, arginine 86, glycine 102, aspartic acid 135 and tyrosine 264 were conserved. Measurement of the transcription level of the bla(ACT-1) gene using real-time quantitative PCR showed that it increased 1.98-fold following cefoxitin induction. These results suggest that the plasmid-mediated bla(ACT-1) gene originated from the chromosome of E. hormaechei.
authors.affiliation: Department of Laboratory Medicine, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Roh
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, Seoul, Republic of Korea.
authors.forename: Wonkeun
authors.initials: W
authors.lastname: Song
authors.affiliation: Department of Laboratory Medicine, Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hae-Sun
authors.initials: HS
authors.lastname: Chung
authors.affiliation: Department of Laboratory Medicine, Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Yang Soon
authors.initials: YS
authors.lastname: Lee
authors.affiliation: Department of Clinical Laboratory Science, Dong-eui University, Busan, Republic of Korea.
authors.forename: Jong Hwa
authors.initials: JH
authors.lastname: Yum
authors.affiliation: School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul, Republic of Korea.
authors.forename: Ha Na
authors.initials: HN
authors.lastname: Yi
authors.affiliation: School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul, Republic of Korea.
authors.forename: Jong Sik
authors.initials: JS
authors.lastname: Chun
authors.affiliation: Department of Laboratory Medicine, Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Dongeun
authors.initials: D
authors.lastname: Yong
authors.affiliation: Department of Laboratory Medicine, Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Kyungwon
authors.initials: K
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine, Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Yunsop
authors.initials: Y
authors.lastname: Chong
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002440:Cefoxitin / Q000494:pharmacology; D002510:Cephalosporinase / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004754:Enterobacter / Q000145:classification / Q000187:drug effects / Q000235:genetics*; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D012336:RNA, Ribosomal, 16S; D002440:Cefoxitin; D002510:Cephalosporinase; C048795:AmpC beta-lactamases; D001618:beta-Lactamases