Objective To evaluate antibacterial activities in vivo and in vitro of fleroxacin and
lomefloxacin. Methods Minimal inhibitory concentration(MIC) and serum bactericidal activity (SBA) domestic fleroxacin and lomefloxacin were determined by agar disk dilution method and microplate method
respectively. A clinical observation of fleroxacin and lomefloxacin for treating acute bacillary dysentery was carried out. Results MIC 90 of fleroxacin against E.coli, K.
pneumoniae, S.
dysenteriae, S.aureus was 0.25～2 mg/L, being the same as that of
ofloxacin. However, MIC 90 of lomefloxacin against the above mentioned species was twice or fourfold as that of ofloxacin and fleroxacin. The percent age of peak SBA≥1∶8 with ofloxacin, fleroxacin and lomefloxacin against E.coli, K. pneumoniae, S.dysenteriae was 80%～100%, 90%～100% and 50%～80% respectively ( P <0.01). The clinical cure rates of acute bacillary dysentery were 93.3%,100% and 100% and the bacterial clearance rates were 93.3%, 100% and 100% in the lomefloxacin, fleroxacin and ofloxacin group respectively. Conclusion The antibacterial activity in vivo and in vitro of fleroxacin against E. coli, K. pneumoniae, S.dysenteriae was similar to that of ofloxacin and stronger than that of lomefloxacin.