Evolution and resistance expression of MRSA. Evaluation of beta-lactam antibiotics against a set of isogenic strains with different types of phenotypic expression

Acta Biochim Pol. 1995;42(4):517-24.


Methicillin-resistant Staphylococcus aureus (MRSA) has two mechanisms of resistance to beta-lactam antibiotics; one is mediated by mecA gene expression, and the other by penicillinase production. It has been generally accepted in the clinical field that beta-lactam antibiotics are not the drugs of choice for MRSA infection. In this report, however, ampicillin and penicillin G were shown to have relatively good activity against MRSA if combined with a beta-lactamase inhibitor, sulbactam. These beta-lactam antibiotics were found to have relatively high binding affinities to PBP2', the mecA-encoded MRSA-specific penicillin-binding protein. The possible therapeutic application of sulbactam/ampicillin against MRSA infection in combination with arbekacin, an aminoglycoside antibiotic newly developed and introduced into clinical use in Japan, is discussed.

MeSH terms

  • Ampicillin / metabolism
  • Ampicillin / pharmacology
  • Anti-Bacterial Agents / pharmacology*
  • Drug Resistance, Microbial / genetics
  • Methicillin / pharmacology*
  • Microbial Sensitivity Tests
  • Penicillin G / metabolism
  • Penicillin G / pharmacology
  • Penicillinase / genetics
  • Phenotype
  • Plasmids
  • Staphylococcus aureus / drug effects*
  • Staphylococcus aureus / genetics
  • Staphylococcus aureus / metabolism


  • Anti-Bacterial Agents
  • Ampicillin
  • Penicillinase
  • Penicillin G
  • Methicillin