729. Real World Efficacy of Bezlotoxumab for Prevention of Clostridioides Difficile Recurrence in Immunosuppressed Patients

BACKGROUND: Bezlotoxumab has been shown to prevent recurrent episodes of C. difficile infection (CDI) in high risk patients. Current studies define therapeutic efficacy within the first 12 weeks when the risk of recurrence is greatest. However, the risk of recurrent CDI can occur beyond the 12-week window in the immunosuppressed population. Given that bezlotoxumab has detectable serum levels for up to 24 weeks after infusion, the primary endpoint is to determine overall efficacy in immunosuppressed patients with recurrent CDI at 4 weeks, 12 weeks, and 24 weeks after initial infusion. Secondary endpoints consist of risk factors for recurrent CDI, treatment of CDI, and antibiotics usage before and after bezlotoxumab. METHODS: This analysis included immunosuppressed patients at high risk for CDI recurrence who received bezlotoxumab from February 2017 to December 2019. Patients were excluded if they were not immunosuppressed, had no follow-up appointments, and/or without a C. difficile positive test. High risk antibiotics included fluoroquinolones, beta lactamase inhibitors, third generation cephalosporins, or carbapenems. RESULTS: Twenty-seven bezlotoxumab doses were given to 26 patients. Baseline characteristics for CDIs prior to bezlotoxumab is reported in Table 1. The overall CDI recurrence rate at all intervals after bezolotoxumab was 4 (15%), one recurrent CDIs occurred at < 4 weeks, two recurrent CDIs occurred at 5-12 weeks, and one recurrent CDI at 13-24 weeks. High risk antibiotics were given in 2/4 (50%) of CDIs recurrences and 22/75 (29%) in the non-recurrence group. Of the four CDI recurrences, all were mild to moderate in disease severity given no evidence of colitis was seen on CT scan and a median Zar score of 1 (range 0-1) due to age > 60 years. Table 1: Baseline Characteristics [Image: see text] CONCLUSION: In immunosuppressed patients with CDI, bezlotoxumab is effective at reducing CDI episodes up to 24 weeks. Additionally, this highly antibiotic exposed population continued to receive benefit up to 24 weeks after bezlotoxumab. DISCLOSURES: All Authors: No reported disclosures