Lower risk of urinary tract infection with low-dose trimethoprim/sulfamethoxazole compared to dapsone prophylaxis in older renal transplant patients on a rapid steroid-withdrawal immunosuppression regimen.

BACKGROUND: Urinary tract infections (UTI) are common in renal transplant recipients. Trimethoprim/sulfamethoxazole (TMP/SMZ) in moderate to high daily doses prevents Pneumocystis jiroveci (PCP) and reduces the risk of UTI in renal transplant patients. Low-dose TMP/SMZ also reduces the risk of PCP, although its ability to reduce the risk of UTI is uncertain.
DESIGN: Retrospective review of 158 patients who received a renal transplant without corticosteroids for maintenance immunosuppression.
RESULTS: Forty percent of patients initially prescribed TMP/SMZ ultimately stopped this medication early because of an adverse reaction. Urinary infection occurred in 16% without a significant difference in the risk of UTI between those treated with dapsone vs. those treated with TMP/SMZ (HR [95%CI]: 1.7 [0.75, 3.9], p = 0.2). In the subset of patients who were older than age 47 yr (mean age for this cohort, SD ± 6.2 yr), those treated with dapsone originally or who switched from TMP/SMZ to dapsone had a greater risk of UTI compared to patients who remained on TMP/SMZ (HR [95%CI]: 4.3 [1.2, 15.5], p = 0.024).
CONCLUSIONS: For renal transplant recipients over the age of 47 yr, treated without long-term glucocorticoids, our retrospective data suggest that low-dose TMP/SMZ is associated with a lower risk of UTI compared to dapsone prophylaxis.