title: Molecular epidemiology of integron-associated antimicrobial gene cassettes in the clinical isolates of Acinetobacter baumannii from northern Taiwan.
abstract: BACKGROUND
  The aims of this study were to understand the molecular epidemiology of integron-associated gene cassettes in Acinetobacter baumannii across four hospitals in northern Taiwan and to clarify the relationship between the presence of integrons and antibiotic-resistant phenotypes.
  
  
  METHODS
  Sixty-five A. baumannii isolates, collected from the patients of four regional hospitals in northern Taiwan in 2009, were tested for the presence of integrons and their associated gene cassettes. The susceptibility difference between integron-positive and integron-negative A. baumannii strains was analyzed. Antibiotic-resistant phenotypes among A. baumannii with different types of gene cassette array combinations were also compared.
  
  
  RESULTS
  Around 72% of the A. baumannii isolates carried class 1 integrase genes. Despite this, only three gene cassette arrays were found in the integrons. Integron-positive strains were significantly more resistant to all the tested antibiotics than the integrase-negative strains. All the four types of A. baumannii with different gene cassette array combinations were multidrug-resistant in nature. Gene cassette array aacA4-catB8-aadA1 existed in all the integron-positive A. baumannii isolates. Repetitive-sequence-based PCR (rep-PCR) results revealed the prevalence of one major cluster of imipenem-resistant A. baumannii strains (84%) in the four regional hospitals.
  
  
  CONCLUSIONS
  The presence of integrons with associated antimicrobial resistance gene cassettes can be used as a representative marker of multidrug resistance in A. baumannii. Some prevalent gene cassette arrays may exist among epidemiologically unrelated A. baumannii strains.
authors.affiliation: Department of Medicine, National Taiwan University Hospital Chu-Tung Branch, Hsin-Chu County, Taiwan.
authors.forename: Ming-Feng
authors.initials: MF
authors.lastname: Lin
authors.forename: Ming-Li
authors.initials: ML
authors.lastname: Liou
authors.forename: Chi-Chao
authors.initials: CC
authors.lastname: Tu
authors.forename: Hui-Wen
authors.initials: HW
authors.lastname: Yeh
authors.forename: Chung-Yu
authors.initials: CY
authors.lastname: Lan
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D019426:Integrases / Q000235:genetics; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D060885:Multiplex Polymerase Chain Reaction; D013624:Taiwan / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015378:Imipenem; D019426:Integrases
keywords: Acinetobacter baumannii; Antimicrobial; Integron