P-1504. Propensity-Matched Comparison of Early vs. Late Antibiotic Therapy in <i>Stenotrophomonas maltophilia</i> Pneumonia: A Five-Hospital Study

Abstract Background Stenotrophomonas maltophilia is a leading drug-resistant nosocomial pathogen worldwide. First-line antibiotic therapy for S. maltophilia is not a routine part of empiric antibiotic coverage. This study aimed to evaluate clinical outcomes of patients receiving early versus late antibiotic therapy for S. maltophilia pneumonia (PNA).Table 1.Baseline and Clinical Course Characteristics aData are presented as “number (%)” or “median (interquartile range)”, as appropriate. Abbreviations: BMI, body mass index; CrCL, creatinine clearance; LTAC, long-term acute care; NH/LTC, nursing home/long-term care. Methods A retrospective, observational study was conducted at five hospitals within University of Kentucky HealthCare. Patients treated for S. maltophilia PNA between 1/1/2014 and 12/31/2023 receiving sulfamethoxazole/trimethoprim, minocycline or levofloxacin with reported in-vitro susceptibility were included. Patient and bacterial characteristics, all-cause mortality, and desirability of outcome ranking (DOOR) at 30 days were compared between patients receiving early (≤48 hours of culture collection) versus late ( &amp;gt;48 hours of culture collection) therapy (Table 1). Propensity-score matching (PSM) was used to adjust confounding. Subgroup and sensitivity analyses were used to verify the robustness of results.Table 2.Desirability of Outcome Ranking (DOOR) Results Median age of patients was 64 years (interquartile range [IQR] 52-71 years). The median Charlson Comorbidity Index and SOFA score were 4 (IQR 2-6) and 4 (2-7). At the time of index culture collection, 219/430 (50.9%) patients were in the intensive care unit, and 142/430 (33%) patients were on mechanical ventilation. Overall mortality at 30 days was 103/430 (24%). DOOR distribution of outcomes is shown in Figure 1. A randomly selected patient with early antibiotic administration had a 69% (95% CI 56%-79%, p&amp;lt; 0.001) likelihood of a better outcome as compared to a randomly selected patient receiving late antibiotic therapy.Figure 1.DOOR Analysis of All Patients with S. maltophilia Pneumonia Receiving Early vs. Late Antibiotic Therapy Conclusion S. maltophilia PNA is associated with poor outcomes, especially in patients receiving therapy with in-vitro activity &amp;gt;48 hours from index culture collection. Disclosures All Authors: No reported disclosures