Gemifloxacin mesylate inhibits activities of DNA gyrase and topoisomerase IV, thereby inhibiting DNA replication and eventually bacterial growth. Gemifloxacin Mesylate is the mesylate salt form of gemifloxacin, a synthetic broad-spectrum fluoroquinolone with antibacterial activity. This fluoroquinolone exerts an enhanced spectrum of activity against gram-positive bacteria such as Streptococcus pneumonia and Staphylococcus aureus, in addition to its activity against gram-negative bacteria.