Polymyxin B for Urinary Tract Infections

Indications and Usage

Polymyxin B should be reserved for treating infections produced by bacteria showing resistance to all beta-lactams, fluoroquinolones, and other first-line agents 1
The Infectious Diseases Society of America recommends polymyxin B as a drug of last resort for carbapenem-resistant gram-negative bacterial (CRGNB) infections, including those causing UTIs 2

First-line antibiotics for uncomplicated UTIs include amoxicillin-clavulanic acid, nitrofurantoin, and sulfamethoxazole-trimethoprim, as recommended by the European Society of Clinical Microbiology and Infectious Diseases 3
For pyelonephritis and prostatitis, the American Urological Association recommends ciprofloxacin (if local resistance patterns allow), ceftriaxone, or cefotaxime 3

The recommended loading dose of polymyxin B is 2-2.5 mg/kg, with a maintenance dose of 1.5-3 mg/kg/day divided in two doses, according to the Intensive Care Medicine guidelines 4
No dosage adjustment is necessary for patients on continuous renal replacement therapy, as stated by the Intensive Care Medicine guidelines 4

The Journal of Urology recommends attempting treatment with first-line agents (nitrofurantoin, TMP-SMX, fosfomycin) before considering polymyxin B 5
The Journal of Microbiology, Immunology and Infection suggests reserving polymyxin B for UTIs caused by carbapenem-resistant gram-negative bacteria 2
Regular monitoring of renal function is recommended during polymyxin B therapy, as well as consideration of therapeutic drug monitoring where available, according to the Journal of Microbiology, Immunology and Infection 2