Twenty isolates resistant to seven quinolones were isolated from major rivers in Korea. All isolates had three mutations, Ser83$ ightarrow$Leu and Asp87$ ightarrow$Asn in GyrA and Ser80$ ightarrow$Ile or Ser80$ ightarrow$Arg in ParC and three isolates had an additional mutation Glu84$ ightarrow$Gly or Glu84$ ightarrow$Val in ParC. In addition, a clonal spread was not found in these isolates.