Reversible Hypokalemia and Bartter-Like Syndrome during Prolonged Systemic Therapy with Colistimethate Sodium in an Adult Patient

We present the case of a 58-year-old woman who developed hypokalaemia and metabolic alkalosis 2 weeks after therapy with colistimethate sodium for the treatment of chronic lower limb ulcer infection by extensively drug-resistant (XDR) Pseudomonas aeruginosa. The metabolic changes observed resembled Bartter syndrome, a group of congenital disorders affecting the distal segments of the renal tubules. The metabolic abnormalities reversed spontaneously 6 days after drug discontinuation. Acquired forms of Bartter syndrome have been reported during courses of antibiotic therapy; however, to our knowledge, this is the first documented case associated with colistimethate therapy in an adult.