Molecular epidemiology of clinical Pseudomonas aeruginosa isolates carrying IMP-1 metallo-beta-lactamase gene in a University Hospital in Turkey

Microb Drug Resist. Fall 2007;13(3):191-8. doi: 10.1089/mdr.2007.748.


Pseudomonas aeruginosa isolates carrying IMP- or VIM-type metallo-beta-lactamase (MBL) have been increasingly reported in hospitals worldwide. One hundred P. aeruginosa clinical isolates from unrelated inpatients hospitalized at a Turkish university hospital were screened for the presence of bla(IMP) and bla(VIM) genes by polymerase chain reaction (PCR). One (1%) isolate was found to carry a VIM-type MBL gene, whereas nine (9%) carried an IMP-1 MBL gene carried on a cassette inserted into a class 1 integron. Only four of the IMP producers were detected as MBL producers according to E-test MBL. Minimum inhibitory concentrations (MICs) of imipenem for the IMP-1 and VIM-type MBL-producers were highly variable (MIC values, 8-128 mug/ml). Imipenem resistance was not plasmid-mediated according to the transformation assays. Piperacillin/tazobactam was the only effective drug in antimicrobial susceptibility testing. No aztreonam-resistant IMP and VIM producers were detected to produce an extended-spectrum beta-lactamase (ESBL). Three class 1 integrons of approximately 2,300 bp, 1,800 bp, and 1,500 bp in size were detected in each of the nine IMP-positive isolates. Sequencing revealed three novel gene cassette arrays, aac(3)-1c-cmlA5, bla(IMP-1)-aadA7-like, and aacA7-smr-2-orfD. Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) indicated that a clonal spread of IMP-1-producers had occurred in this hospital.

MeSH terms

  • Anti-Bacterial Agents / administration & dosage
  • Anti-Bacterial Agents / pharmacology*
  • Aztreonam / pharmacology
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Genes, Bacterial
  • Hospitals, University
  • Humans
  • Imipenem / administration & dosage
  • Imipenem / pharmacology
  • Integrons
  • Microbial Sensitivity Tests
  • Molecular Epidemiology
  • Molecular Sequence Data
  • Penicillanic Acid / administration & dosage
  • Penicillanic Acid / analogs & derivatives
  • Penicillanic Acid / pharmacology
  • Piperacillin / administration & dosage
  • Piperacillin / pharmacology
  • Piperacillin, Tazobactam Drug Combination
  • Plasmids
  • Polymerase Chain Reaction
  • Pseudomonas Infections / epidemiology
  • Pseudomonas Infections / microbiology*
  • Pseudomonas aeruginosa / drug effects*
  • Pseudomonas aeruginosa / genetics
  • Pseudomonas aeruginosa / isolation & purification
  • Turkey / epidemiology
  • beta-Lactamases / genetics


  • Anti-Bacterial Agents
  • Piperacillin, Tazobactam Drug Combination
  • Imipenem
  • Penicillanic Acid
  • VIM-1 metallo-beta-lactamase
  • beta-lactamase IMP-1
  • beta-Lactamases
  • Aztreonam
  • Piperacillin

Associated data

  • GENBANK/DQ899757