IN-VITRO AND IN-VIVO ACTIVITY OF A NEW QUINOLONE AM-1155 AGAINST MYCOPLASMA-PNEUMONIAE

We investigated the in-vitro and in-vivo activity of a new quinolone A M-1155 against Mycoplasma pneumoniae, and compared it with ofloxacin, ciprofloxacin, lomefloxacin, tosufloxacin, erythromycin and minocyclin e. AM-1155 was the most potent agent in vitro of the quinolones tested . Its pre-treatment minimal inhibitory concentrations for 90% of the 4 1 strains (MIC(90)) was 0.06 mg/L. In contrast, pre-treatment MIC(50) values for ofloxacin, ciprofloxacin, lomefloxacin, tosufloxacin, eryth romycin, and minocycline were 1, 1, 2, 0.5, 0.0156, and 0.5 mg/L, resp ectively. Post-treatments MIC(90)s, which may reflect mycoplasmacidal potency, of AM-1155, ofloxacin, ciprofloxacin, lomefloxacin, tosufloxa cin, erythromycin and minocycline were 0.125, 1, 2, 4, 0.5, 0.125 and 4 mg/L, respectively. In-vitro activities of antimicrobial agents were assessed in an experimental pulmonary infection model in Syrian golde n hamsters. AM-1155 was the most effective agent among five antimicrob ial agents (AM-1155, ofloxacin, tosufloxacin, erythromycin, minocyclin e) tested in terms of reduction in viable M. pneumoniae cells and in r educing macroscopic lung lesions. These results suggest that AM-1155 w ill be a useful antimicrobial agent for the treatment of M. pneumoniae infections.