662. Recurrence of Infection and Emergence of Drug Resistance After Treatment with Meropenem/Vaborbactam Compared with Ceftazidime/Avibactam in Carbapenem-Resistant Enterobacteriaceae Infections

BACKGROUND: Options for treatment of carbapenem-resistant Enterobacteriaceae (CRE) infections were historically limited to antibiotics with limited efficacy and significant toxicities. Ceftazidime/avibactam (CA) and meropenem/vaborbactam (MV) are superior to older regimens; however, a direct comparison of the agents is lacking. This study compared clinical outcomes including recurrence of infection and emergence of drug resistance in patients who received CA vs. MV for CRE infections. METHODS: This was a multicenter, retrospective cohort study of adults with CRE infections who received CA or MV for ≥72 hours from February 2015 to October 2018. Patients with localized urinary tract infection were excluded. The primary endpoint was clinical success (30-day survival, resolution of signs and symptoms of infection, sterilization of blood cultures within 7 days in patients with bacteremia, absence of recurrent infection). Secondary endpoints included 30- and 90-day mortality, adverse events (AE), recurrent CRE infection within 90 days, and development of resistance in patients with recurrent infection. We conducted a post hoc subgroup analysis in patients with recurrence to compare development of resistance in those who received CA monotherapy, CA combination therapy, and MV monotherapy. RESULTS: 131 patients were included (CA: 105 patients, MV: 26 patients), 40% had bacteremia. No statistical difference in clinical success was observed between groups (62% vs. 69%, respectively, P = 0.49). Patients in the CA arm received combination therapy more often than patients in the MV arm (61% vs. 15%, P < 0.01). No difference in 30- and 90-day mortality resulted among groups, but numerically higher rates of AE were observed in the CA group (38% vs. 23%, P = 0.17). In patients with recurrent infection, development of resistance occurred more often with CA monotherapy, though not statistically significant (Table 1). One case of MV resistance was observed in a patient who had received 4 prior courses of MV, but this episode was outside of the study period. CONCLUSION: Clinical success was similar between the groups despite MV being used more often as monotherapy. Development of resistance and rates of AE were higher in the CA group compared with MV therapy. [Image: see text] DISCLOSURES: All authors: No reported disclosures.