Objectives: To evaluate the in vivo antibacterial efficacy of chinfloxacin, a novel fluoroquinolone, in murine systemic and local infection models.
Methods: The efficacy of chinfloxacin in systemic infection was evaluated in a mouse peritonitis model using isolates of methicillin-susceptible Staphylococcus aureus (MSSA, n = 3), methicillin-resistant Staphylococcus aureus (MRSA; n = 1), penicillin-intermediate Streptococcus pneumoniae (PISP; n = 1), penicillin-resistant S. pneumoniae (PRSP; n = 2), vancomycin-susceptible Enterococcus faecalis (VSE; n = 1), vancomycin-resistant E. faecalis (VRE; n = 2), Escherichia coli (n = 3) and Klebsiella pneumoniae (n = 2). The local infections included mouse pulmonary infections caused by penicillin-susceptible S. pneumoniae (PSSP; n = 1), PRSP (n = 1) and K. pneumoniae (n = 2).
Results: In the mouse systemic infection model, chinfloxacin demonstrated potent activity against MSSA [50% effective dose (ED(50)) 2.28-4.15 mg/kg], MRSA (ED(50) 14.75 mg/kg), PISP (ED(50) 6.20 mg/kg), PRSP (ED(50) 3.51-5.03 mg/kg), VSE (ED(50) 25.02 mg/kg), VRE (ED(50) 5.18-15.39 mg/kg), E. coli (ED(50) 1.25-1.90 mg/kg) and K. pneumoniae (ED(50) 2.92-8.28 mg/kg). The therapeutic efficacy of chinfloxacin was generally similar to (P > 0.05) that of moxifloxacin, significantly higher (P < 0.01 or P < 0.05) than that of levofloxacin in Gram-positive isolate infections (MSSA, MRSA, PISP, PRSP, VSE and VRE), and less than that of levofloxacin against E. coli and K. pneumoniae infections (P < 0.01). In the mouse pulmonary infection model, chinfloxacin showed potent activity towards S. pneumoniae (higher than levofloxacin and ciprofloxacin) and K. pneumoniae (lower than levofloxacin and similar to or higher than ciprofloxacin) infections.
Conclusions: The results validated the potent efficacy of chinfloxacin in vivo. The high efficacy of chinfloxacin in murine systemic and local infections warrants investigation of its clinical use.