727 - Outcomes of Antibiotic Use in Ischemic Colitis

Background: Ischemic colitis (IC) is caused by inadequate blood flow to the colon. Most cases resolve with conservative management. Isolated right-sided colitis, peritonitis, shock, and vascular risk factors are predictors of severe disease which can be life-threatening and require surgery. Current guidelines recommend antibiotics for moderate/severe disease. This is based on results from animal models and concern for gut translocation of bacteria; there have been no comparative studies in humans. This study aims to evaluate whether there is benefit to antibiotic use in non-severe IC.

Methods: This is a single-center retrospective cohort study of adult patients hospitalized with IC from 2015-2018. Inclusion in the study required endoscopic, radiologic, operative, or histologic evidence of ischemic colitis. Patients were divided into mild/moderate and severe IC cohorts as per 2014 American College of Gastroenterology Guidelines. Primary outcomes were length of stay (LOS) and any adverse event, which is defined as a composite measure of pre-specified secondary outcomes including mortality, need for surgery, 1-year relapse, and bacteremia.

Results: Of 191 patients enrolled in the study, 130 had mild/moderate IC and 61 had severe IC. In mild/moderate IC groups there was no significant difference in total adverse events, although use of antibiotics was associated with a significant increase in LOS (Table 1). In the severe IC groups there was no significant difference in any primary outcomes, but mortality was lower at 3 and 6 months among patients who did not receive antibiotics.Table 1


Conclusion: Antibiotics did not improve outcomes in mild/moderate IC, suggesting that conservative management may be sufficient in this group. Antibiotic use was associated with increased LOS in mild/moderate IC and with increased mortality in severe IC; it is not clear whether these associations are true antibiotic-mediated adverse effects or whether they simply reflect a tendency to use antibiotics more frequently in patients who are more unstable. Future prospective research is needed to establish clear guidelines for antibiotic indications, agent selection, and optimal treatment duration.