Impact of institutional treatment guidance on the management and outcomes of Stenotrophomonas maltophilia and carbapenem-resistant Acinetobacter baumannii infections.

Objective: To evaluate the impact of a guidance document on treatment decisions and clinical outcomes for infections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) and Stenotrophomonas maltophilia. Design: This was a single-center, retrospective, quasi-experimental, pre- and post-intervention study. The primary outcome was adherence to antibiotic selection and dosing as recommended by the guidance document. Secondary outcomes included clinical efficacy, readmission within 90 days, all-cause 30-day mortality, 90-day microbiologic recurrence, and antibiotic-associated adverse effects. Setting: The study was conducted at a large, academic medical center in the Southeastern United States. Participants: The study included adult patients who were admitted to our institution from November 2018 to June 2024 who grew CRAB or S. maltophilia from any culture and were definitively treated. Intervention: This study included an institution specific treatment algorithm for the treatment of infections caused by resistant gram-negative organisms published on June 1st, 2022, on our institution's antimicrobial stewardship website. Results: Twenty-two patients with CRAB (14 pre- and 8 post-intervention) and 150 with S. maltophilia (75 pre- and 75 post-intervention) were evaluated. For CRAB, 0 (0%) patients in the pre-intervention group and 5 (62.5%) in the post-intervention group met the primary outcome (P < .001). For S. maltophilia, 21 (28%) patients in the pre-intervention group compared to 38 (50.7%) in the post-intervention group met the primary outcome (P < .004). Secondary outcomes did not differ significantly pre- and post-intervention. Conclusions: These findings demonstrate that implementing a local treatment guideline based on IDSA guidance may increase the utilization of evidence-based directed antimicrobial therapy for CRAB and S. maltophilia.