ADAPTIVE MUTATIONS PRODUCE RESISTANCE TO CIPROFLOXACIN

Mutation to ciprofloxacin resistance continually occurred in nondividi ng Escherichia coli cells during a 7-day exposure to ciprofloxacin in agar, while no accumulation of rifampin resistance mutations was detec ted in those cells. We propose that the resistance mutations result fr om adaptive mutations, which preferentially produce phenotypes that pr omote growth in nondividing cells.