In vitro activity of tosufloxacin against bacterial enteric pathogens

The in vitro activity of tosufloxacin (A-61827), a new quinolone antibiotic, was compared with that of four other quinolones against 162 bacterial enteric pathogens. Susceptibility testing was performed by using an agar dilution method. The minimal inhibitory concentration (MIC) was defined as the lowest concentration of antibiotic without visible growth. Tosufloxacin was the most active agent against Campylobacter jejuni and C. coli, and ciprofloxacin was the most active agent against Salmonella, Shigella, and Vibrio. The frequency of spontaneous point mutational resistance to tosufloxacin for three C. jejuni ranged from 1.2 x 10(-9) to 5.1 x 10(-13). No significant differences in mutational frequency were seen among the quinolones.