Determination by LC-MS/MS of colistins A and B in plasma and ultrafiltrate from critically ill patients undergoing continuous venovenous hemodiafiltration.

Background:Colistin is a 50-year-old antibiotic, the use of which was ceased in the 70s and recently resumed as a “salvage therapy” against multidrug-resistant gram-negative bacteria, such as Pseudomonas aeruginosa and Acinetobacterbaumannii. The narrow therapeutic range of colistin makes the choice