Tolerability of low-dose sulfamethoxazole/trimethoprim for Pneumocystis jirovecii pneumonia prophylaxis in kidney transplant recipients.

Background- Pneumocystis jirovecii pneumonia (PCP) is an opportunistic infection seen in immunosuppressed patients, including solid-organ transplant recipients. Sulfamethoxazole/trimethoprim (SMX/TMP) has long been considered first-line therapy for PCP prophylaxis. Optimal dosing regimens in solid-organ transplant recipients have not been fully defined. Objective-To examine the tolerability of a 1-year, 3-times weekly, prophylactic regimen of a single-strength SMX/TMP tablet. Study Design-Single-center, retrospective cohort study. Setting-A tertiary-care medical center, including inpatient hospitalizations and outpatient transplant clinic visits. Patients-Adult patients who received a kidney transplant between December 1, 2010, and November 30, 2012, at Hartford Hospital. Patients receiving a concurrent extrarenal transplant were excluded. Patients' charts were reviewed for up to 1 year after transplant. Results-A total of 88 patients were included in the analysis. Sixty-seven patients finished a full year of SMX/TMP after transplant, 10 patients discontinued SMX/TMP less than 1 year after transplant, and 11 patients started taking atovaquone instead of SMX/TMP after transplant. Documented reasons for discontinuation included hyperkalemia, leukopenia, diarrhea, and simplification of medication regimen. Patients without a documented reason for discontinuation did not have any obvious anomalies in laboratory values that would account for the discontinuation. Patients who received atovaquone for PCP prophylaxis had higher rates of recurrent urinary tract infections than did patients who received SMX/TMP for prophylaxis (33% vs 7%, P = .02). A longer postoperative stay (median [interquartile range, IQR] 13 [8.25-26] days vs 7 [6-9.5] days, P = .02), higher rates of delayed graft function (50% vs 10%, P = .004), as well as higher serum creatinine levels on postoperative day 7 (6.25 [2.4-10.1] mg/dL vs 1.8 [1.2-4.2] mg/dL, P= .01), postoperative month 1 (1.9 [0.8] mg/dL vs 1.4 [0.5] mg/dL, P = .002), and postoperative month 12 (1.6 [0.5] mg/dL vs 1.3 [0.3] mg/dL, P = .04) were associated with early SMX/TMP discontinuation. Conclusion-A low-dose prophylactic SMX/TMP regimen of 1 single-strength tablet 3 times weekly is well tolerated. Discontinuation rates were lower than other rates reported for higher-dose regimens.