Seven-day antibiotic therapy for Enterobacterales bacteremia in high-risk neutropenic patients: Toward a new paradigm

Purpose . Data on short courses of antibiotic therapy for Enterobacterales bacteremia in high-risk neutropenic patients are limited. The aim of the study was to describe and compare the frequency of bacteremia relapse, 30-day overall and infection-related mortality, Clostridiodes difficile infection and length of hospital stay since bacteremia among those who received antibiotic therapy for 7 or 14 days. Methods. This is a multicenter, prospective, observational cohort study in adult high-risk neutropenic patients with hematologic malignancies or hematopoietic stem cell transplant and monomicrobial Enterobacterales bacteremia. They received appropriate empirical antibiotic therapy, had a clinical response within 7 days, and infection source control. Clinical, epidemiological and outcomes variables were compared based on 7 or 14 days of AT. Results. Two hundred patients were included (100, 7-day antibiotic therapy; 100, 14-day antibiotic therapy). No differences were observed in baseline characteristics between both groups. Escherichia coli was the pathogen most frequently isolated (47.5%), followed by Klebsiella sp . (40.5%). Among those patients that received 7-day vs. 14-day antibiotic course, a clinical source of bacteremia was found in 54% vs. 57% (p=0.66), multidrug-resistant Enterobacterales isolates in 28% vs. 30% (p=0.75), and 40% vs. 47% (p=0.31) received combined empirical antibiotic therapy. Overall mortality was 3% vs. 1% (p=0.62), in no case related to infection; bacteremia relapse was 7% vs. 2% (p=0.17), and length of hospital stay since bacteremia had a median of 9 days (IQR: 7-15) vs. 14 days (IQR: 13-22) (p=<0.001). Conclusions. These data suggest that seven-day antibiotic therapy might be adequate for patients with high-risk neutropenia and Enterobacterales bacteremia, who receive appropriate empirical therapy, with clinical response and infection source control.