Introduction: Hospital-acquired bloodstream infections (HA-BSIs) are severe and require antibiotic therapy. In non-complicated BSIs, shortened therapy reduces side effects without compromising efficacy. The impact of shortened antibiotic therapy in HA-BSI critically ill patients without indication of prolonged therapy requires further evaluation.

Methods: Using the international prospective EUROBACT-2 cohort, we compared shortened (7-10 days) versus long (14-21 days) treatment durations in ICU patients eligible for shortened therapy. Patients without antibiotic therapy within 3 days after HA-BSI occurrence or requiring prolonged therapy (due to infection source, microorganism, or clinical deterioration) were excluded. Treatment failure, defined as death, persistent infection, or subsequent infectious complications by Day 28, was assessed using an inverse-probability of treatment weighted (IPTW) logistic regression.

Results: Among 2600 patients, 550 were eligible for shortened treatment, 213 received short, and 337 received long treatment. The most common infection source was intravascular catheters (33%), most common microorganisms were Enterobacterales (39%). Patients with long treatment were more frequently infected with Staphylococcus aureus (11% vs. 5.6%, p = 0.025) or difficult-to-treat microorganisms (23% vs. 7%, p < 0.001), and received more commonly combination therapy (46% vs. 30%, p < 0.001). Short treatment was associated with reduced 28-day treatment failure (OR 0.64, 95% CI 0.44-0.93, p = 0.019), mainly due to reduction in subsequent infectious complications (OR 0.58, 95% CI 0.37-0.91, p = 0.018). Mortality (OR 0.92 [95% CI 0.59, 1.43], p = 0.7) and persistent infection rates (OR 0.47 [95% CI 0.17, 1.14], p = 0.12) were similar.

Conclusions: In selected ICU patients with HA-BSI, shortened antibiotic treatment might be considered. Eurobact2 was a prospective international cohort study, registered in ClinicalTrials.org (NCT03937245).