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Published on: May 8, 2013
Detection of SHV-1 beta-lactamase in Pseudomonas aeruginosa strains by genetic methods
S Kalai Blagui1, W Achour, M Bejaoui
1Service des laboratoires, centre national de greffe de moelle osseuse de Tunis, rue Djebel-Lakdhar-Bab-Saadoun, 1006 Tunis, Tunisia.
Abstract:
Twelve multidrug-resistant Pseudomonas aeruginosa (MDRPA) isolates were recovered over a period of two years in the National Bone Marrow Transplant Centre of Tunisia. MDRPA isolates were isolated from seven patients and from three environmental samples. Isoelectric focusing revealed pIs of 8.2, 5.5 and 7.6 in all MDRPA isolates. These strains produced the OXA-18 extended spectrum beta-lactamase and an SHV type beta-lactamase as shown by screening PCR analysis. DNA hybridization confirmed this inference, detecting bla(SHV) gene in these isolates. Pulsed-field gel electrophoresis (PFGE) defined one predominant genomic group; group A (seven isolates) and four different genotypes containing one to two isolates. Clonally related isolates were recovered from three patients and from two washbasins. Sequencing DNA of cluster representative strains identified the classical bla(SHV-1) gene. For these strains, the nucleotide sequence of the structural bla(SHV-1) gene was nearly identical to those previously described. Such enzyme has not been reported from P. aeruginosa. This is the first report of the SHV-1 penicillinase in epidemic P. aeruginosa strain.
Insights
Multidrug-resistant Pseudomonas aeruginosa strains carrying the SHV-1 beta-lactamase gene were identified in a Tunisian bone marrow transplant center. This marks the first report of SHV-1 penicillinase in epidemic Pseudomonas aeruginosa.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Multidrug-resistant Pseudomonas aeruginosa (MDRPA) poses a significant threat in healthcare settings, particularly in immunocompromised populations.
- The emergence of novel resistance mechanisms in MDRPA necessitates continuous surveillance and characterization.
Purpose of the Study:
- To investigate the genetic and molecular characteristics of MDRPA isolates from a National Bone Marrow Transplant Centre.
- To identify the specific beta-lactamase enzymes and genetic relatedness among these clinical and environmental isolates.
Main Methods:
- Isolation and characterization of MDRPA from patient and environmental samples.
- Isoelectric focusing for pI determination.
- Screening PCR, DNA hybridization, and sequencing to identify beta-lactamase genes (OXA-18, bla(SHV)).
- Pulsed-field gel electrophoresis (PFGE) for genomic typing.
Main Results:
- Twelve MDRPA isolates were recovered from patients and environmental sources.
- All isolates produced OXA-18 and an SHV-type beta-lactamase, with bla(SHV) gene detected.
- PFGE revealed one predominant genomic group (group A) and four other genotypes.
- Sequencing identified the bla(SHV-1) gene, nearly identical to known sequences, in representative strains.
- Clonally related isolates were found in patients and washbasins.
Conclusions:
- This study reports the first occurrence of the SHV-1 penicillinase in epidemic Pseudomonas aeruginosa strains.
- The findings highlight the potential for clonal spread of MDRPA carrying specific resistance genes within a transplant center.
- Continuous monitoring for emerging resistance mechanisms in P. aeruginosa is crucial in high-risk clinical environments.
