Acute kidney injury occurred in 11% of TMP-SMX recipients but nearly always resolved after drug discontinuation.

Trimethoprim-sulfamethoxazole (TMP-SMX) is widely used to treat urinary tract and soft-tissue infections. Despite anecdotal reports indicating the possibility of TMP-SMX–associated renal toxicity, systematic investigation has been lacking.

To remedy this situation, researchers in Texas reviewed the records of consecutive male inpatients at a Veterans Affairs Medical Center who, during a 3-year period, had received TMP-SMX for ≥6 days to treat urinary tract or soft-tissue infections. All had blood urea nitrogen (BUN) and serum creatinine levels measured both ≤7 days before starting and ≤3 days after completing therapy.

Among 573 patients, 64 (11%) had increases in both BUN and serum creatinine levels that met predetermined criteria for acute kidney injury. The kidney injury was classified as probably caused by TMP-SMX in 33 patients (6%), possibly caused by TMP-SMX in 28 (5%), and probably unrelated to the drug in 3.

No relation was found between the dose of TMP-SMX — or the duration of treatment — and the likelihood of acute kidney injury. On multivariate analysis, hypertension and diabetes were the only independent risk factors for such injury. Fifty-four of the 64 patients with kidney injury had follow-up testing ≤1 month after TMP-SMX discontinuation; in 52 (93%), renal function had returned to baseline. One patient required dialysis.

Comment: TMP-SMX–associated renal toxicity seems to occur more often than previously thought. Although this effect appears to be transient, regular monitoring of renal function is warranted during and immediately after TMP-SMX therapy.

—Thomas Glück, MD

Published in Journal Watch Infectious Diseases April 4, 2012

CITATION(S):

Fraser TN et al. Acute kidney injury associated with trimethoprim/sulfamethoxazole. J Antimicrob Chemother 2012 Feb 20; [e-pub ahead of print]. [Medline® Abstract]