Purpose: Shortening the duration of antibiotic therapy (ABT) is a key measure in antimicrobial stewardship. The optimal duration of ABT for treatment of postoperative intra-abdominal infections (PIAI) in critically ill patients is unknown.
Methods: A multicentre prospective randomised trial conducted in 21 French intensive care units (ICU) between May 2011 and February 2015 compared the efficacy and safety of 8-day versus 15-day antibiotic therapy in critically ill patients with PIAI. Among 410 eligible patients (adequate source control and ABT on day 0), 249 patients were randomly assigned on day 8 to either stop ABT immediately (n = 126) or to continue ABT until day 15 (n = 123). The primary endpoint was the number of antibiotic-free days between randomization (day 8) and day 28. Secondary outcomes were death, ICU and hospital length of stay, emergence of multi drug-resistant (MDR) bacteria and re operation rate, with 45-day follow-up.
Results: Patients treated for 8 days had a higher median number of antibiotic-free days than those treated for 15 days (15 [6–20] vs 12 [6–13] days, respectively; P < 0.0001) (Wilcoxon rank difference 4.99 days [95% CI 2.99–6.00; P < 0.0001). Equivalence was established in terms of 45-day mortality (rate difference 0.038, 95% CI − 0.013 to 0.061). Treatments did not differ in terms of ICU and hospital length of stay, emergence of MDR bacteria or re-operation rate, while subsequent drainage between day 8 and day 45 were observed following short-course ABT (P= 0.041).
Conclusion: Short-course antibiotic therapy in critically ill ICU patients with PIAI reduces antibiotic exposure. Continuation of treatment until day 15 is not associated with any clinical benefit.