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Why can polymyxin antibiotics also be toxic to human cells?
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Polymyxin antibiotics, such as polymyxin B and polymyxin E (colistin), function by binding to phospholipids within the cell membrane of bacteria. This binding disrupts the membrane's role as a selective barrier, causing essential macromolecules to leak out and leading to the death of the bacterial cell.21
These antibiotics are toxic to human cells because human cells also contain similar or identical phospholipids in their own membranes. Consequently, polymyxins can interact with and damage human cell membranes, which may result in adverse effects such as kidney damage and neurotoxicity. Due to this lack of selective toxicity compared to other available treatments, the clinical use of polymyxins is often limited.21