title: Molecular mechanisms of carbapenem resistance in Enterobacter cloacae clinical isolates from Korea and clinical outcome.
abstract: We investigated the molecular mechanisms of carbapenem resistance in clinical isolates of Enterobacter cloacae and their clinical characteristics. Nonreplicable E. cloacae isolates were recovered from six cancer patients and one patient with liver cirrhosis at a tertiary-care hospital in Korea between 2002 and 2009. Two patients who were considered to have a true infection caused by these microorganisms have died. All isolates produced AmpC β-lactamases, including ACT-1, ACT-2, MIR-3 and DHA-1, and CTX-M- or SHV-type extended-spectrum β-lactamase. Two isolates produced plasmid-borne VIM-2 carbapenemase. All probes specific for bla(AmpC) genes hybridized with I-CeuI chromosomal fragments were also recognized by a probe specific for 16S rDNA, suggesting a chromosomal location. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that a major outer membrane protein, OmpF, was absent in all isolates. PFGE of XbaI-digested DNA were considered to be unrelated. The results of our study suggest that the chromosomal AmpC β-lactamase with impermeability in E. cloacae clinical isolates implicated in reduced carbapenem susceptibility. Although carbapenem-resistant E. cloacae isolates were isolated in a few patients in our study, the clinical outcomes were grave. Therefore, the patients colonized or infected by carbapenem-resistant E. cloacae isolates should gain attention of antibiotic therapy.
authors.affiliation: Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Yangsoon
authors.initials: Y
authors.lastname: Lee
authors.forename: Heekyeong
authors.initials: H
authors.lastname: Choi
authors.forename: Jong Hwa
authors.initials: JH
authors.lastname: Yum
authors.forename: Girung
authors.initials: G
authors.lastname: Kang
authors.forename: Il Kwon
authors.initials: IK
authors.lastname: Bae
authors.forename: Seok Hoon
authors.initials: SH
authors.lastname: Jeong
authors.forename: Kyungwon
authors.initials: K
authors.lastname: Lee
mesh_terms: D000368:Aged; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D015780:Carbapenems / Q000494:pharmacology*; D002648:Child; D004352:Drug Resistance, Microbial / Q000187:drug effects* / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D016972:Enterobacter cloacae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D005260:Female; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D056910:Republic of Korea; D016896:Treatment Outcome; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D001425:Bacterial Outer Membrane Proteins; D015780:Carbapenems; D001618:beta-Lactamases