Source Control in Pseudomonas aeruginosa Bloodstream Infections: An Overlooked Pillar in Reducing 30-Day All-Cause Mortality

Background: Appropriate antibiotic therapy is a key determinant of outcomes in Pseudomonas aeruginosa bloodstream infection (BSI), but the impact of adequate source control on prognosis has not been well defined in large cohorts. Methods: We conducted a retrospective multicenter study including hospitalized patients with P. aeruginosa BSI across 14 Italian hospitals between January 2021 and December 2022. Results: Overall, 639 BSI episodes were analyzed. The most frequent sources were an unknown source (31.8%), central venous catheter BSI (22.5%), hospital-acquired/ventilator-associated pneumonia (20.3%), urinary tract infections (11.4%), and intra-abdominal infections (6.9%). Source control was required in 34.0% of cases and was achieved early and adequately in 49.3% of these. The 30-day all-cause mortality rate was 23.9%. Mortality was significantly lower in patients who received early adequate source control (6.5%) compared with those without early adequate source control (23.6%) or in whom it was deemed unnecessary (28.4%) (P < .0001). In multivariable analysis, age, corticosteroid therapy, and septic shock were independently associated with increased mortality, whereas prior P. aeruginosa colonization, early adequate source control, and appropriate antibiotic therapy were protective. A propensity score–matched analysis confirmed the association between early adequate source control and reduced 30-day mortality (adjusted hazard ratio 0.15; P = .0024). Conclusions: Early adequate source control is a critical determinant of survival in P. aeruginosa BSI. Outcomes are optimized by a combined approach integrating timely source control with appropriate antibiotic therapy.