Colistimethate Products | Cleanchem - Colistimethate is an antibiotic used to treat infections caused by multidrug-resistant Gram-negative bacteria, particularly Pseudomonas aeruginosa. It works by disrupting the bacterial cell membrane, leading to cell death. Colistimethate is often used in hospital settings, particularly for treating infections in patients with cystic fibrosis or those in intensive care units. Potential side effects include nephrotoxicity (kidney damage) and neurotoxicity, including dizziness and tingling sensations.