Polymyxins

• Used topically - external otitis, eye infections, skin infections
• To sterilise gut

Examples

• Polymyxin B
• Colistin (Polymyxin E)

Mechanism of action

• insert into bacterial membranes
• produces increased cell permeability

Activity

• Gram negative

Resistant

• Gram positive - do not have outer membrane

Risks

• severe nephrotoxicity