Pefloxacin (Pefloxacinium) mesylate dihydrate is a broad spectrum antibiotic. Pefloxacin mesylate dihydrate blocks DNA replication by inhibiting DNA gyrase. Pefloxacin mesylate dihydrate inhibits DNA relaxation catalyzed by topoisomerase I with an IC50 of 45 µg/mL. Pefloxacin mesylate dihydrate exhibits antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Bacteroides fragilis with MIC90s of 0.12, 4, and 16 mg/L, respectively. Pefloxacin mesylate dihydrate has anti-Plasmodium yoelii infection activity. Pefloxacin mesylate dihydrate increase UVA-induced edema and immunesuppression. Pefloxacin mesylate dihydrate can be used for infection studies[1][2][3][4][5][6][7][8][9].