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DW-224a showed the most potent in vitro activity among the quinolone compounds tested against clinical isolates of gram-positive bacteria. Against gram-negative bacteria, DW-224a was slightly less active than the other fluoroquinolones. The in vivo activities of DW-224a against gram-positive bacteria were more potent than those of other quinolones. The classic fluoroquinolones such as ciprofloxacin, norfloxa-cin, fleroxacin, and ofloxacin have shown strong activity against gram-negative bacteria, but the effectiveness of these com-pounds against gram-positive bacteria has been debated (1, 4). Recently, the emergence of multidrug-resistant gram-positive pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant coagulase-negative staphylococci, penicillin-resistant Streptococcus pneumoniae, and vancomycin-resistant enterococci, has generated worldwide concern in the medical community (2, 5, 6, 11). Therefore, recent efforts have been directed toward the synthesis of novel quinolone com