Following statement is false regarding Colistin:

Option A: Colistin belongs to a group of antimicrobial agents known as Polymyxins, which were originally isolated from the spore-forming soil organism Paenibacillus polymyxa. Molecules in this group are polymyxins A, B, C, D & E, of which only polymyxin E (Colistin) and Polymyxin B are used clinically in humans. Option B: Colistin is a mixture of polymyxin E1 and E2, two bactericidal pentacationic lipopeptides. The mode of action of colistin is not fully elucidated but involves binding to lipopolysaccharides and phospholipids in the outer membrane of Gram-negative organisms, which results in membrane disruption and cell death. Option C: Colistin is active against a wide variety of Gram-negative bacteria and is not active against Gram-positive bacteria, which lack an outer membrane. Option D: Colistin is used in both human and veterinary medicine. In humans, colistin is generally used to treat infections with multidrug-resistant, extensively drug-resistant and pan drug-resistant Bacteria.