Molecular epidemiology of clinical Pseudomonas aeruginosa isolates carrying the IMP-1 Metallo-beta-Lactamase gene in a University hospital in Turkey

Ozgumus O. B., Caylan R., Tosun I., Sandalli C., Aydin K., Koksal I.

MICROBIAL DRUG RESISTANCE, vol.13, no.3, pp.191-198, 2007 (SCI-Expanded) identifier identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 13 Issue: 3
  • Publication Date: 2007
  • Doi Number: 10.1089/mdr.2007.748
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.191-198
  • Acibadem Mehmet Ali Aydinlar University Affiliated: No


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-I MBL gene carried on a cassette inserted into a class I 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 mu g/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-cm1A5, bla(Imp.1)-aadA7-like, and aacA7-smr-2-orfD. Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) indicated that a clonal spread of IMP-I-producers had occurred in this hospital.