Molecular Characterization of Resistance to Mupirocin in Methicillin-Susceptible and -Resistant Isolates of Staphylococcus aureus from Nasal Samples

A total of 15 of 101 (14.8%) nasal methicillin-resistant Staphylococcus aureus (MRSA) isolates exhibited mupirocin resistance (Mup r ) compared with 1 of 154 (0.6%) methicillin-susceptible Staphylococcus aureus isolates. A total of 14 (93%) isolates exhibiting high-level Mup r belonged to a single clone. Horizontal plasmid transfer and transmission of Mup r strains contribute to a high incidence of Mup r MRSA at our institution.