2254. Multicenter Evaluation of Ceftazidime–Avibactam for Multidrug-Resistant Pseudomonas aeruginosa Infections

BACKGROUND: Ceftazidime–avibactam (CZA) is a novel cephalosporin/β-lactamase inhibitor with activity against carbapenem-resistant Enterobacteriaceae (CRE) and multidrug-resistant (MDR) Pseudomonas aeruginosa (PA). Real-world experience with CZA for CRE infections is accumulating but data on its use for MDR PA infections remains limited. METHODS: Retrospective, multicenter cohort study describing the clinical characteristics and outcomes of patients treated with CZA (≥ 72 hours) for MDR PA infections between 2015 and 2018. RESULTS: Fifty-one patients were included. The median (IQR) age was 61 (43, 71) years. Most patients had MDR risk factors including recent hospitalization (74.5%), recent antimicrobial exposure (84.3%), and/or previous infection or colonization with an MDR pathogen (58.8%). The median Charlson Comorbidity score was 4 (2, 6) and the median APACHE II score was 20 (12, 29). Infections were predominantly (68.6%) hospital-acquired and 52.9% of patients were in the ICU at infection onset. The common sources were respiratory tract (60.8%), osteoarticular (11.8%) and skin and soft tissue (11.8%). Two patients had positive blood cultures. PA antibiotic susceptibilities were as follows: ceftazidime 52.6% (n = 51), CZA 92.0% (n = 25), ciprofloxacin 10% (n = 30), meropenem 19.6% (n = 46), piperacillin–tazobactam 30.4% (n = 4) and tobramycin 72.9% (n = 48). Most (60.8%) infections were polymicrobial including 15 (29.4) CRE co-infections. CZA was started 97 (50, 170) hours after culture collection and continued for 9 (7, 14) days. Only 8 patients (15.7%) received active antibiotic therapy before CZA. Combination CZA therapy was used 35.3%, most often an aminoglycoside (8/18, 44.4%). Clinical cure or improvement was achieved in 40 patients (78.4%), and 42 (82.4%) were discharged alive. Among patients with repeat cultures (n = 11), CZA resistance development was not detected. Three patients (5.9%) experienced infection recurrence within 30 days of completing therapy. CONCLUSION: The use of CZA was associated with high rates of favorable outcomes in complex patients with MDR PA infections. Future studies evaluating long-term outcomes and comparative studies are needed to more precisely define the role of CZA for MDR PA infections. DISCLOSURES: All authors: No reported disclosures.