Low- versus high-dose trimethoprim-sulfamethoxazole for the treatment of Stenotrophomonas maltophilia pneumonia.

Objective: To compare outcomes of patients treated with low-dose (LD) versus high-dose (HD) trimethoprim-sulfamethoxazole (TMP-SMX) for Stenotrophomonas maltophilia pneumonia.

Design: Retrospective cohort study.

Setting: Large academic tertiary-care center.

Patients: Hospitalized adult patients who received at least 8 mg/kg/day of TMP-SMX for at least 96 hours for treatment of S. maltophilia pneumonia between October 2012 and September 2022. Patients were included if they were diagnosed with pneumonia based on clinical and radiographic findings at the time of initiation of antibiotics.

Methods: The primary outcome was clinical success at the end of therapy among patients treated with LD (8-12 mg/kg/day) versus HD (>12 mg/kg/day) TMP-SMX. Secondary outcomes included microbiological success, all-cause and infection-related inpatient mortality, infection recurrence, development of TMP-SMX resistance, and incidence of acute kidney injury (AKI) and hyperkalemia.

Results: 95 patients were included (LD, n = 20 versus HD, n = 75). There was no difference in the primary outcome of clinical success at the end of therapy between groups (LD 57% versus HD 65%, P = 0.53). Secondary outcomes, including inpatient infection-related mortality (P = 0.56), AKI (P = 0.61), and hyperkalemia (P = 0.34) also did not differ significantly between the LD and HD groups.

Conclusions: No differences in clinical success or adverse events were observed in patients with S. maltophilia pneumonia treated with either LD or HD TMP-SMX.