ASSOCIATION OF ORGANIC-SOLVENT TOLERANCE AND FLUOROQUINOLONE RESISTANCE IN CLINICAL ISOLATES OF ESCHERICHIA-COLI

Fluoroquinolone resistance in Escherichia coli is principally caused b y two kinds of mutation: those affecting the target proteins of the dr ugs, i.e. DNA gyrase and topoisomerase IV, and those affecting regulat ory genes such as marA, soxS or robA. Recently, overexpression of the latter genes was linked to increased organic solvent tolerance in E. c oil, Among 138 clinical fluoroquinolone-resistant and -susceptible cli nical isolates of E. coli we found a high association between fluoroqu inolone resistance and organic solvent tolerance. This finding suggest s that E. coli may undergo an adaptive response to extrinsic substance s other than quinolones while mutating to fluoroquinolone resistance.