Reversible neurotoxicity associated with polymyxin B: a case report

Abstract

Polymyxin B is a potent antibiotic used against multidrug-resistant Gram-negative infections such as Acinetobacter baumannii and Pseudomonas aeruginosa. It acts by disrupting the bacterial outer membrane, leading to cell death. Despite its effectiveness, its use is limited by a narrow safety margin and notable toxicities. The most common adverse effects are kidney injury and neurotoxicity, while symptoms such as fever, rash, headache, or chest tightness occur less often. Neurotoxic effects can range from mild paresthesia to severe neuromuscular impairment. This case describes a 60-year-old patient who developed perioral numbness, chest tightness, and headache shortly after receiving polymyxin B, highlighting the need for close monitoring even at therapeutic doses. This case is distinctive because the constellation of perioral numbness, chest tightness, and headache occurred in the absence of renal dysfunction, and symptoms resolved promptly with discontinuation of polymyxin B and supportive diuretic therapy. Such a presentation has not been widely described in prior reports, underscoring the need for vigilance even when dosing is within therapeutic ranges. Polymyxin B remains an important therapeutic agent for multidrug-resistant Gram-negative infections; however, its neurotoxic potential necessitates close observation during treatment. In our case, the patient developed transient neurological symptoms that improved following discontinuation of polymyxin B and supportive management with diuretics, including furosemide (Lasix). This highlights the importance of early recognition and prompt intervention to prevent serious toxicity while maintaining therapeutic efficacy.