P-14. Unmasking the Enemy: Clinical and Microbiological Insights into P. aeruginosa Bacteremia

Abstract Background P. aeruginosa bacteremia presents significant treatment challenges due to resistance patterns and high mortality. This study aimed to characterize the clinical features, antimicrobial therapy, and outcomes associated with P. aeruginosa bacteremia and identify predictors of in-hospital mortality Methods This retrospective cohort study included all inpatients with an initial episode of P. aeruginosa bacteremia at UK HealthCare between July 2022 and December 2024. Of 970 patients with positive blood cultures for monomicrobial Gram-negative bacteria, 91 (9.4%) had P. aeruginosa bacteremia. Data were obtained through structured chart review and the Center for Clinical and Translational Science. Univariate analysis using SPSS identified mortality predictors. Results Median (IQR) age was 66 yrs (50, 74); 87.9% were White. Comorbidities included chronic kidney disease (46.2%), peripheral vascular disease (44.0%), COPD (37.4%), and diabetes (24.2%). Infections were hospital-acquired in 51.6%, and 56.0% required ICU admission. In-hospital mortality was 30.8%, and 47.3% were readmitted within 90 days. Median hospital and ICU stays were 17 (8, 32) and 7.0 days (4.1, 14.3), respectively. Initial empiric therapy included cefepime (CFP, 48.3%), piperacillin/tazobactam (PTZ, 27.5%), meropenem (MER, 9.9%), ceftolozane/tazobactam (C/T, 2.2%), and miscellaneous agents (12.1%). Definitive therapy reflected similar trends: CFP (44.0%), PTZ, MER, and miscellaneous (16.5% each), and C/T (6.5%). Carbapenem resistance was 15%. ID consultation occurred in 57.1% of cases, with no difference between ICU and non-ICU patients (54.9% vs 60.0%, p=NS). Mortality was associated with ICU admission (p=0.004), qPITT (p=0.006), SOFA (p=0.011), hospital-acquired infection (p=0.039), and indwelling catheter (p=0.046). Conclusion Among patients with Gram-negative bacteremia, P. aeruginosa accounted for 9.4% of cases and was associated with high mortality, frequent ICU admission, and prolonged hospitalization. CFP and PTZ were the most common therapies; novel agent use was limited. Mortality was linked to critical illness and nosocomial acquisition. Findings support timely risk assessment, ID consultation, and optimized therapy. Disclosures All Authors: No reported disclosures