title: Epidemiological characterizations of class 1 integrons from multidrug-resistant acinetobacter isolates in Daejeon, Korea.
abstract: BACKGROUND
  Multidrug-resistant (MDR) Acinetobacter spp. acquire antimicrobial agent-resistance genes via class 1 integrons. In this study, integrons were characterized to investigate the antimicrobial resistance mechanisms of MDR Acinetobacter isolates. In addition, the relationship between the integron type and integron-harboring bacterial species was analyzed by using epidemiological typing methods.
  
  
  METHODS
  Fifty-six MDR Acinetobacter spp.-A. baumannii (N=30), A. bereziniae (N=4), A. nosocomialis (N=5), and A. pittii (N=17)-were isolated. The minimum inhibitory concentrations (MICs) were determined on the basis of the results of the Epsilometer test (Etest). PCR and DNA sequencing was performed to characterize the gene cassette arrays of class 1 integrons. Multilocus sequence typing (MLST) and repetitive extragenic palindromic sequence (REP)-PCR were performed for epidemiological typing.
  
  
  RESULTS
  Class 1 integrons were detected in 50 (89.3%) of the 56 isolates, but no class 2 or 3 integron was found within the cohorts. The class 1 integrons were classified into 4 types: 2.3-kb type A (aacA4-catB8-aadA1), 3.0-kb type B (aacA4-blaI MP-1 -bla OXA-2), 3.0-kb type C (bla VIM-2-aacA7-aadA1), and 1.8-kb type D (aac3-1-bla OXA-2 -orfD). Type A was most prevalent and was detected only in A. baumannii isolates, except for one A. bereziniae isolate; however, type B was amplified in all Acinetobacter isolates except for A. baumannii isolates, regardless of clone and separation time of the bacteria.
  
  
  CONCLUSIONS
  Although class 1 integron can be transferred horizontally between unrelated isolates belonging to different species, certain types of class 1 integrons tend to transfer horizontally and vertically among A. baumannii or non-baumannii Acinetobacter isolates.
authors: Department of Biomedical Laboratory Science, Far East University, Eumseong, Korea.
authors: Ji Youn
authors: JY
authors: Sung
authors: Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea.
authors: Sun Hoe
authors: SH
authors: Koo
authors: Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea.
authors: Semi
authors: S
authors: Kim
authors: Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea.
authors: Kye Chul
authors: KC
authors: Kwon
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D016133:Polymerase Chain Reaction; D056910:Republic of Korea
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial
keywords: Integron; MDR Acinetobacter spp.; MLST; Sequence types