BackgroundCeftolozane/tazobactam is a novel cephalosporin and β-lactamase inhibitor antibiotic that has shown to have potent activity against Pseudomonas aeruginosa including strains exhibiting multi-drug resistance (MDR). The purpose of this study was to evaluate ceftolozane/tazobactam efficacy in MDR P. aeruginosa pneumonia compared with historical standard of care.MethodsThis was a retrospective cohort study of patients hospitalized across AdventHealth Central Florida campuses with MDR P. aeruginosa pneumonia from January 1, 2017 through December 31, 2018. This study included patients ≥ 18 years of age with a diagnosis of pneumonia and a positive respiratory culture with MDR P. aeruginosa. The primary outcome of this study was the rate of clinical cure by day 14 of definitive therapy. Secondary outcomes included 30-day readmission rate, average hospital length of stay (LOS), cost of admission, average ICU LOS after initiation of definitive antibiotic, and total days of antibiotic exposure for pneumonia. Data were analyzed with statistical computer software utilizing independent samples t-test and chi square tests of independence as appropriate.ResultsA total of 115 patients were included in the final analysis, 62 patients treated with ceftolozane/tazobactam and 53 patients treated with historical standard of care. Rate of clinical cure was similar between patients treated with ceftolozane/tazobactam, 72.6% (n = 45), and those treated with historical standard of care, 67.9% (n = 36), {X2 (1) = 0.297, p = 0.683}. Other outcomes assessed were also similar between groups except for average hospital length of stay (42.7 days vs. 30.3 days t(113) = 2.054, p = 0.042), and cost of admission ($78,550 vs. $47,681, t(113) = 2.458, p = 0.016), which were significantly greater in the ceftolozane/tazobactam treatment group.ConclusionIn patients diagnosed with MDR P. aeruginosa pneumonia, clinical cure rates were not significantly different between those treated with ceftolozane/tazobactam compared with historical standard of care. Significantly greater hospital length of stay and cost of admission was associated with use of ceftolozane/tazobactam, although many patient factors may have influenced these results.Disclosures All authors: No reported disclosures.