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Published on: February 19, 2019
Genomic organization of a vancomycin-resistant Staphylococcus aureus
Zulfiqar Ali Mirani1, Nusrat Jamil
1Microbiological Analytical Centre, PCSIR Laboratories Complex, Karachi. mirani_mrsa@yahoo.com
Journal of the College of Physicians and Surgeons--Pakistan : JCPSP
|February 5, 2013
Summary
This study investigated the genetic basis of vancomycin resistance in a local Staphylococcus aureus isolate. The vanA cassette, responsible for resistance, was identified and characterized, confirming its transferability.
Area of Science:
- Molecular Biology
- Microbiology
- Genomics
Background:
- Vancomycin-resistant Staphylococcus aureus (VRSA) poses a significant public health threat.
- Understanding the genomic organization of resistance mechanisms is crucial for combating VRSA.
- Previous studies have identified various vancomycin resistance genes, but their organization in local isolates requires investigation.
Purpose of the Study:
- To elucidate the genomic organization of vancomycin resistance in a specific VRSA isolate (VRSA-CP2) from Karachi.
- To characterize the vanA cassette and its associated genes within the isolate.
- To confirm the transferability of vancomycin resistance.
Main Methods:
- Isolation and identification of VRSA-CP2.
- Confirmation of vancomycin resistance via E-test.
- Plasmid DNA extraction and PCR amplification of vanA cassette genes (vanR, vanS, vanH, vanA, vanY, orf2, IS element).
- DNA sequencing of amplified products and BLAST analysis.
- Conjugation experiments to transfer vancomycin resistance to a sensitive strain.
Main Results:
- The VRSA-CP2 isolate exhibited resistance to multiple antibiotics, including vancomycin (MIC 16 μg/ml).
- Agarose gel electrophoresis indicated the presence of three plasmids.
- PCR confirmed the presence of the vanA cassette, including vanR, vanS, vanH, vanA, vanY, and orf2, along with an insertion element (IS).
- Vancomycin resistance was successfully transferred to a sensitive S. aureus recipient, with the transformant showing a similar MIC.
- Sequencing revealed partial homology of the vanA cassette with those found in vancomycin-resistant enterococci and other VRSA strains.
Conclusions:
- The vanA cassette in the CP2 isolate shares genetic similarities with known vancomycin resistance elements in enterococci and other VRSA.
- The findings contribute to understanding the genetic diversity and dissemination of vancomycin resistance mechanisms.
- Further research into the specific genetic elements and their regulation is warranted.
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