Colistin is a polymyxin antibiotic discovered in 1947 from the bacterium Paenibacillus polymyxa var. colistinus (formerly Bacillus polymyxa), and it was introduced into clinical use in the late 1950s for the treatment of Gram-negative bacterial infections, particularly those caused by organisms like Pseudomonas aeruginosa. Initially valued for its strong activity against resistant bacteria, its use declined in the 1970s due to significant nephrotoxicity and neurotoxicity concerns, leading to the development of safer antibiotics. However, with the global rise of multidrug-resistant Gram-negative pathogens such as carbapenem-resistant Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas, colistin experienced a clinical revival in the 21st century as a last-resort therapeutic option, especially in intensive care settings.
