Non-Target Gene Mutations in the Development of Fluoroquinolone Resistance in Escherichia coli

Mutations in loci other than genes for the target topoisomerases of fluoroquinolones, gyrA and parC , may play a role in the development of fluoroquinolone resistance in Escherichia coli . A series of mutants with increasing resistance to ofloxacin was obtained from an E. coli K-12 strain and five clinical isolates. First-step mutants acquired a gyrA mutation. Second-step mutants reproducibly acquired a phenotype of multiple antibiotic...