Mutations in rpoB and fusA cause resistance to rifampicin and fusidic acid in methicillin-resistant Staphylococcus aureus strains from a tertiary hospital in Malaysia

Abstract Background The prevalence of resistance to rifampicin and fusidic acid among Malaysian strains of methicillin-resistant Staphylococcus aureus (MRSA) is increasing. This study aimed to determine the mechanisms of rifampicin and fusidic acid resistance and the genetic diversity of MRSA strains from a Malaysian tertiary hospital. Methods Minimum inhibitory concentrations (MIC) for 21 MRSA strains were determined by agar dilution test and Etest. The resistance genes, staphylococcal chromosome cassette mec (SCCmec) types, multilocus-sequence typing (MLST) types and spa types, were determined by PCR and DNA sequencing. Results MIC for rifampicin and fusidic acid resistance ranged from <1 to 8 µg/ml and from