Back

Genetic analysis of metallo-beta-lactamase producing Klebsiella pneumoniae and Pseudomonas aeruginosa isolates in the intensive care unit of a university general hospital in Greece

Abstract number: p1413

Koratzanis  E., Galani  I., Souli  M., Chryssouli  Z., Giamarellou  H.

Objective: 

During a study for the evolution and horizontal transfer of metallo-B-lactamase(MBL) genes from commensal to pathogenic gram-negative bacteria in patients of an intensive care unit of a tertiary care university hospital, we analysed the integrons carrying the MBL gene in K. pneumoniae and P. aeruginosa isolates.

Methods: 

Isolates from surveillance cultures as well as isolates considered pathogenic from the same patient that exhibited a positive EDTA-imipenem disk synergy test were studied. Susceptibility testing was performed by the disk diffusion technique and MICs were determined by the broth microdilution method according to NCCLS guidelines. EDTA-disc synergy test, was used to screen for MBL production. PCR and PCR-RFLP analysis and Southern hybridization were used to identify and analyse the blaVIM-containing integrons.

Results: 

All isolates exhibited reduced susceptibility or resistance to imipenem (0.5–>8 mg/ml) and a positive EDTA-synergy test. Strains were resistant to ceftazidime, ceftriaxone and cefotaxime. Class I integrons associated with VIM-type MBL genes were found in all strains. Preliminary PCR-based experiments and RFLP analysis revealed the presence of 5 different integrons (1500–5500 bp) carrying blaVIM-1 in K. pneumoniae isolates. The predominant type is that of 1500 bp probably corresponding to an integron containing only blaVIM-1 gene cassette. A new integron containing blaVIM-1 and aac (6´)-IIc that has been characterized by our group in an Enterobacter cloacae clinical isolate was also found in a K. pneumoniae isolate. Interestingly, the same patient was also colonized by a Citrobacter freundii carrying the same integron. PCR and Southern hybridization revealed the presence of 2 integrons (both >2 kb) carrying blaVIM-2 in all of the P. aeruginosa isolates. The size and RFLP analysis revealed no similarities between the integrons of P. aeruginosa and those of K. pneumoniae.

Conclusions: 

MBLs of the VIM-type represent an emerging threat in Greek hospitals. All isolates of our study harboured blaVIM-1 (K. pneumoniae) or blaVIM-2 (P. aeruginosa), in class I integrons. We observed: 1) the diversity of blaVIM-1 containing integrons in different K. pneumoniae isolates of the same patient and the integration of the same class I integrons in K. pneumoniae nosocomial isolates of different patients and 2) no similarities of VIM-containing integrons from P. aeruginosa and K. pneumoniae isolates even those isolated from the same patient.

Session Details

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