Methicillin-Resistance in Staphylococcus aureus Is Not Affected by the Overexpression in Trans of the mecA Gene Repressor: A Surprising Observation
2011

Methicillin-Resistance in Staphylococcus aureus and the mecA Gene Repressor

publication Evidence: moderate

Author Information

Author(s): Oliveira Duarte C., de Lencastre Hermínia

Primary Institution: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa

Hypothesis

Does the overexpression of the mecA gene repressor affect methicillin resistance in MRSA strains?

Conclusion

The overexpression of the mecA repressor did not significantly alter the phenotypic expression of β-lactam resistance in most MRSA strains.

Supporting Evidence

  • MRSA strains with a non-functional mecI-mecR1 system showed high-level β-lactam resistance.
  • Overexpression of mecI did not significantly change resistance levels in most strains tested.
  • A conserved mutation in mecI was found in SCCmec type III strains, leading to a truncated protein.

Takeaway

Scientists studied a gene that controls antibiotic resistance in bacteria. They found that making this gene work harder didn't change how resistant the bacteria were to the medicine.

Methodology

The study involved sequencing the mecI coding region and mecA promoter sequences in MRSA strains, followed by transforming strains with a plasmid overexpressing mecI.

Limitations

The study did not explore all potential regulatory mechanisms affecting mecA transcription.

Digital Object Identifier (DOI)

10.1371/journal.pone.0023287

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