The emergence of Staphylococcus aureus with reduced susceptibility to vancomycin in Japan

Am J Med. 1998 May 29;104(5A):7S-10S. doi: 10.1016/s0002-9343(98)00149-1.


Within the past year, infections caused by methicillin-resistant Staphylococcus aureus (MRSA) strains with reduced susceptibility to vancomycin (MIC=8 microg/mL) have been reported in both Japan and the United States. The emergence of these strains poses a potentially serious threat to public health. After 2 such strains (Mu3 and Mu50) were identified at Juntendo Hospital in 1996, a screening program to identify MRSA strains with reduced susceptibility to vancomycin was initiated. Of 970 MRSA strains tested at 195 nonuniversity hospitals throughout Japan, 13 (1.3%) were found to have subpopulations with reduced vancomycin susceptibility (heterogeneous vancomycin resistance). Among 129 MRSA strains identified at 7 university hospitals, 12 (9.3%) demonstrated heterogeneity for vancomycin resistance; 1 of these strains had a vancomycin MIC of 7 microg/mL. Although resistance in these strains is not the result of the transfer of enterococcal vancomycin resistance genes (vanA or vanB), the clonal dissemination of MRSA strains with vancomycin-resistant subpopulations is obviously undesirable. Intensified testing of MRSA strains for resistance to vancomycin and appropriate measures for the prevention of the spread of such strains are recommended.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Drug Resistance, Microbial
  • Drug Resistance, Multiple*
  • Humans
  • Japan
  • Methicillin Resistance*
  • Microbial Sensitivity Tests
  • Staphylococcal Infections / drug therapy*
  • Staphylococcus aureus / drug effects*
  • Vancomycin / pharmacology*


  • Anti-Bacterial Agents
  • Vancomycin