Background: The optimal duration of antimicrobial therapy for treatment of complicated intra-abdominal infections (cIAI) in critically ill surgical patients is unknown. Recent evidence suggests that a short (four-day) course of therapy may be effective, however data in severely critically ill patients are limited.
Patients and methods: A single-center, retrospective, cohort study was conducted at a tertiary academic medical center. Adult patients admitted to the surgical intensive care unit (SICU) with cIAI between December 2011 and July 2015 were enrolled. Patients undergoing transplantation and those with less than 24 h in the SICU were excluded. Patients were divided into two groups, short (≤ 7 d) and long (> 7 d) antimicrobial therapy. The primary outcome was treatment failure, which was defined as a composite of recurrent cIAI, secondary extra-abdominal infection, and/or in-hospital mortality from any cause. Categorical and continuous data were analyzed with χ2 and Mann-Whitney U tests, respectively. Binary logistic regression was performed to determine factors associated with treatment failure and mortality.
Results: Of 1,679 patients screened, 240 were included, 103 in the short and 137 in the long group. Patients in the short and long groups received a median of 5 and 14 d of therapy, respectively (p < 0.001). Treatment failure occurred less frequently with a short duration of therapy (39% versus 63%, p < 0.001) and it occurred two days sooner after source control in patients receiving the shorter courses of antimicrobial therapy (short, median 6 d, interquartile range [IQR] 3-9; long, 8 d, IQR 6-14; p < 0.001). Logistic regression demonstrated that a long duration of therapy was associated with treatment failure (odds ratio [OR] 2.186, 95% confidence interval [CI] 1.251-3.820, p = 0.006), but not with mortality (OR 0.738, 95% CI 0.329-1.655, p = 0.461).
Conclusions: In critically ill surgical patients with cIAI, a short duration of antimicrobial therapy after source control resulted in similar outcomes to previously published studies, providing support for the safety of this approach in critically ill patients.
Keywords: antibiotics; intensive care unit (ICU); intra-abdominal infection; surgery.