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 [Image: see text] 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. DISCLOSURES: All Authors: No reported disclosures