Polymyxin B2, a significant component of polymyxin B, is an antibiotic cationic lipopeptide initially derived from B. polymyxa. This compound effectively inhibits P. aeruginosa, A. baumannii, K. pneumoniae, and E. cloacae strains, exhibiting minimum inhibitory concentrations (MICs) of 1-2, 0.5-1, 0.25-0.5, and 0.25-1 µg/ml, respectively. Notably, in a mouse model of P. aeruginosa bloodstream infection, administration of polymyxin B2 at a dosage of 4 mg/kg has been shown to decrease the number of colony-forming units (CFUs) in the blood.