Risk factors for 30-Day mortality and the role of empirical therapy in Pseudomonas aeruginosa bloodstream infections

Purpose: P. aeruginosa bloodstream infections (BSIs) represent one of the most common conditions associated with increased healthcare costs, prolonged hospitalization and high attributable mortality. The primary objective of our study was to investigate all-cause 30-day mortality associated with P. aeruginosa BSIs. Methods: We conducted a multicenter, retrospective cohort study in 14 Italian hospitals, including all consecutive patients with P. aeruginosa BSIs from January 2021 to December 2022. We included all patients who were ≥ 18 years old with P. aeruginosa BSIs treated for at least 48 h with an anti-Pseudomonal antibiotic regimen that was sensitive in vitro. Results: Six hundred and thirty-nine P. aeruginosa BSIs were collected from participating centers. After applying the exclusion criteria, 511 BSIs remain. The median age was 68.0 (IQR 57.0–77.0). Three hundred and forty (66.5%) patients were male. One hundred eight (21.1%) patients experienced in-hospital 30-day mortality. Most BSIs were caused by susceptible strains of P. aeruginosa (474 isolates, 92.8%). At the multivariate logistic regression analysis, older age [1.03 (1.01–1.05), p = 0.003], presence of sepsis [OR 2.75 (1.43–5.27), p = 0.002], presence of septic shock [6.53 (3.33–12.80), p < 0.001] and high-risk infections [OR 2.74 (1.36–5.49), p = 0.005] were associated with the worst outcome. The combination of empirical therapy [OR 0.39 (0.16–0.96), p = 0.04] was the only variable associated with improved survival. Conclusion: Appropriate empirical therapy with two in vitro active molecules was beneficial in terms of all-cause 30-day mortality, especially in patients with severe clinical presentations, such as septic shock and high-risk infections.