Association of mutations in grlA and gyrA topoisomerase genes with resistance to ciprofloxacin in epidemic and sporadic isolates of methicillin- resistant Staphylococcus aureus

Abstract

The types of topoisomerase alterations in genomically diverse epidemic and sporadic strains of methicillin and finoroquinolone-resistant Staphylococcus aureus isolated from European hospitals between 1984 and 1994 were characterized. Convergent dual mutations in gyrA (codon 83, 84, or 88) and grlA (codon 79 and/or 80) were found in all strains exhibiting high- level resistance to ciprofloxacin (MIC, 16 to ≤128 μg/ml). In some epidemic strains, the resistant phenotype and genotype appeared in the 1990s and persisted thereafter.