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Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
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Plasmid-Encoded Transferable mecB-Mediated Methicillin Resistance in Staphylococcus aureus.
Emerging Infectious Diseases
|January 20, 2018
Summary
A novel methicillin-resistant Staphylococcus aureus (MRSA) strain was identified lacking common resistance genes but possessing a mecB gene on a multidrug-resistance plasmid. This discovery raises concerns about the spread of antibiotic resistance and the effectiveness of beta-lactam treatments.
Area of Science:
- Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant public health threat due to its resistance to beta-lactam antibiotics.
- Standard screening methods rely on detecting specific resistance genes like mecA and mecC.
- Emergence of novel resistance mechanisms can circumvent existing detection and treatment strategies.
Purpose of the Study:
- To characterize a phenotypically identified MRSA isolate that tested negative for common MRSA genes (mecA, mecC).
- To identify the genetic basis of methicillin resistance in this unusual isolate.
- To assess the implications of this novel resistance mechanism for antimicrobial therapy and MRSA spread.
Main Methods:
- Cefoxitin-based nasal screening for MRSA identification.
- Molecular testing for mecA, mecC genes, and SCCmec-orfX junction.
- Whole-genome sequencing or plasmid analysis to identify resistance genes and genetic elements.
- Plasmid characterization, including size and gene content.
Main Results:
- An MRSA isolate was identified that lacked mecA, mecC, and the SCCmec-orfX junction.
- The isolate carried a mecB gene, previously found in Macrococcus caseolyticus but not in staphylococci.
- The mecB gene was located on an 84.6-kb plasmid, also containing genes for resistance to aminoglycosides, macrolides, and tetracyclines.
- The plasmid also contained regulatory genes (mecR, mecI, blaZ) flanking the mecB gene.
Conclusions:
- A novel mechanism of beta-lactam resistance in Staphylococcus aureus mediated by the mecB gene on a multidrug-resistance plasmid has been identified.
- This finding highlights the potential for previously unrecognized resistance genes to emerge and spread within staphylococcal populations.
- The presence of this plasmid-borne resistance mechanism could contribute to the increasing ineffectiveness of beta-lactam antibiotics against staphylococcal infections and warrants further investigation into its epidemiological impact.
Keywords:
MRSAMacrococcusStaphylococcaceaeStaphylococcus aureusantibacterial agentsantimicrobial resistancebacteriamecBmethicillin-resistant Staphylococcus aureusmicrobial genomeplasmidsstaphylococciMore Related Videos
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