6 Enterococci are generally much less virulent than S. aureus, however VRE bacteraemia is associated with a higher mortality when compared to strains that remain antibiotic sensitive. In the laboratory, the complex genome coding for vancomycin resistance has been transferred to S. aureus. In some strains of S. aureus it involves a markedly altered and thicker cell wall as well as changes in penicillin binding proteins. This again however highlights one of the problems with bacteria and antibiotic resistance. We frequently do not have the ability to accurately predict what will happen in the future.
Microbes have the ability to come up with unexpected and novel mechanisms of resistance.
Vancomycin may be needed more frequently to treat community-acquired infections. They are particularly common in some areas in New Zealand, but also found in Australia and the United States of America. Fortunately most strains of cMRSA are not multi-resistant and there remain some therapeutic options available besides vancomycin. However, if we look at what has occurred with MRSA in the past in hospitals, it is almost inevitable with time that these cMRSA strains will become resistant to currently available agents. Strains of MRSA that show heterogenous resistance to vancomycin have already spread within some Japanese hospitals.