IN-VIVO ACTIVITY OF HSR-903, A NEW FLUOROQUINOLONE, AGAINST RESPIRATORY PATHOGENS

The in vivo activity of HSR-903, a new fluoroquinolone, against major bacteria which cause respiratory tract infections was evaluated. HSR-9 03 was active against experimental respiratory tract infections in mic e challenged with penicillin-susceptible and penicillin-resistant Stre ptococcus pneumoniae and Haemophilus influenzae strains. Treatment wit h HSR-903 reduced the bacterial numbers in infected murine lungs. In a ccord with the pulmonary clearance results, the rates of survival for mice treated with HSR-903, sparfloxacin, levofloxacin, ciprofloxacin, and benzylpenicillin were 50, 30, 10, 0, and 0%, respectively, 14 days after being infected with penicillin-resistant S. pneumoniae. A pharm acokinetic study with pneumonic mice showed that the levels of HSR-903 in the lungs were seven to eight times higher than those in the plasm a. These results indicate that clinical studies of HSR-903 against res piratory tract infections may be warranted.