Clinafloxacin(PD-127391) is a fluoroquinolone antibiotic. Target: Antibacterial Clinafloxacin is a broad-spectrum antibiotic of the quinolone carboxylic acid category currently in development for intravenous and oral therapy of serious infections [1]. Clinafloxacin is a novel fluoroquinolone with potent broad-spectrum in vitro activity against gram-positive, gram-negative, and anaerobic pathogens. Clinafloxacin is highly active against S. pneumoniae 7785 (MIC, 0.125 μg/mL), and neither gyrA nor parC quinolone resistance mutations alone have much effect on this activity [2]. Clinafloxacin is identified as the most active fluoroquinolone against S. pneumoniae when compared with ofloxacin, levofloxacin, sparfloxacin, grepafloxacin, and trovafloxacin and is currently being evaluated as an antipneumococcal agent [3].