Neurotoxicity in patients treated with intravenous polymyxin B: Two case reports

Abstract

Two cases of reversible neurotoxicity associated with the administration of intravenous polymyxin B are described. In the first case, a 60-year-old, obese, white woman with a medical history of recurring urinary tract infections, nephrolithiasis, and chronic renal insufficiency was admitted for parenteral antibiotics for dysuria and hematuria despite outpatient management with oral antibiotics. Her urinalysis revealed pyuria and large blood content. The corresponding urine culture contained >or=100,000 colony-forming units/mL of multidrug-resistant (MDR) Klebsiella pneumoniae. The patient was treated with polymyxin B at 20,000 units/kg i.v. as a loading dose and then 10,000 units/kg i.v. daily based on her renal function. The patient experienced oral paresthesia that resolved upon discontinuation of the infusion with no further complications. In the second case, a 57-year-old white man with hypertension and ascending cholangitis was admitted. He required percutaneous drainage of an infected pancreatic cyst and received polymyxin B at 25,000 units/kg i.v. as a loading dose and then 15,000 units/kg i.v. daily in addition to imipenem-cilastatin based on the sensitivities of two organisms (Escherichia coli and MDR K. pneumoniae) isolated from the abdominal drainage. For his pancreatic abscess, the patient received a prolonged course of polymyxin B, which was well tolerated for the first four weeks. On day 30 of the polymyxin B, the patient reported oral and lower extremity paresthesias. The symptoms resolved upon discontinuation of the polymyxin B. Two patients developed symptoms of neurotoxicity after receiving intravenous polymyxin B for the treatment of MDR gram-negative infections.