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Genetic structure of a VIM-2-encoding integron from a Pseudomonas aeruginosa clinical isolate from Belgium

Abstract number: p930

Docquier  J.D., D'Andrea  M.M., Christiaens  G., Boreux  R., Giani   T., Frère  J.M., De Mol  P., Rossolini  G.M.

Objectives: 

Acquired metallo-beta-lactamases (MBLs), due to their extremely broad substrate profile and their potential for diffusion via horizontal transfer of mobile genetic elements, represent a worrisome evolution in the antimicrobial resistance landscape. VIM-type MBLs, first detected in Italy, are now widespread in Europe, Asia and the Americas, and have been detected in clinical isolates of Pseudomonas spp., Acinetobacter spp., Enterobacteriaceae and other nonfastidious gram-negative nonfermenters.

Methods: 

Bacterial identification and susceptibility profiles were determined using an automated Vitek II platform. Carbapenem-resistant clinical isolates obtained in the period Oct–Dec 2003 from different wards of the University Teaching Hospital in Liège (Belgium) were assayed for imipenem-hydrolysing activity using a spectrophotometric test and were screened for the presence of IMP- or VIM-type MBLs by RFLP–PCR. The structure of the MBL-containing class 1 integron was determined by PCR mapping and direct DNA sequencing of amplification products.

Results: 

Among 10 carbapenem-resistant P. aeruginosa isolates, only one produced an EDTA-inhibited imipenem-hydrolysing activity. A PCR analysis revealed the presence of a blaVIM gene. This isolate (3163608), isolated from a decubitus ulcer of a 73-year-old male inpatient, was resistant to most beta-lactam antibiotics (including carbapenems, expanded-spectrum cephalosporins and beta-lactam/beta-lactamase inactivator combinations), aminoglycosides and fluoroquinolones while it was intermediate to aztreonam (MIC, 16 mg/l), gentamicin (8 mg/l) and susceptible to colistin (2 mg/l). DNA sequencing revealed an original integron structure containing two gene cassettes encoding a VIM-2 MBL and an AADA5 aminoglycoside adenylyltransferase, respectively.

Conclusion: 

Although carbapenem-resistant Pseudomonas aeruginosa isolates are relatively unfrequent at our institution, one VIM-2-producing isolate was identified. The original structure of the VIM-2-encoding class 1 integron found in this isolate underlines the important potential of diffusion of such genes in different genetic contexts.

Acknowledgement: 

Supported by EU-HP grant nos. HPRN-CT-2002-00264 and LSHM-CT-2003-503335.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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