Heterogeneous Vancomycin Resistance in Methicillin-Resistant Staphylococcus aureus Strains Isolated in a Large Italian Hospital

Of 179 methicillin-resistant Staphylococcus aureus strains isolated from 1997 to 1998, two strains (1.1%) gave subclones for which the vancomycin MICs were 8 mg/liter. Pulsed-field gel electrophoresis showed identical restriction patterns for both isolates, suggesting transfer of a single clone between two different patients.