1109. A multicenter, observational study to compare the effectiveness of C eftazidime- A vibactam versus C eftolozane- T azobactam for multidrug-resistant Pseudomonas aeruginosa infections in the U nited S tates (CACTUS)

Abstract

Background. Ceftolozane-tazobactam (C/T) and ceftazidime-avibactam (CZA) are preferred treatment options for multidrug-resistant (MDR) Pseudomonas aeruginosa infections; however, real-world comparative-effectiveness studies are lacking. Methods. To compare the efficacy of C/T and CZA, adult patients with MDR P. aeruginosa pneumonia or bacteremia treated with C/T or CZA for >48 hours were enrolled. Patients were matched 1:1 by study site, severity of illness, time to treatment initiation, and infection type. The primary outcome was clinical success at day 30. Findings. 420 patients were enrolled from 28 study sites; 83% and 17% had pneumonia and bacteremia, respectively. Baseline demographics, comorbidities, and severity of illness indicators were all similar between groups. Upon treatment initiation 80% (336/420) of patients were in the intensive care unit, 70% (296/420) received mechanical ventilation, and 40% (168/420) required vasopressor support. Clinical success was achieved in 61% (128/210) and 52% (109/210) of patients treated with C/T and CZA, respectively (P=0.05). By conditional logistic regression analysis, the adjusted odds ratio (aOR) of success following treatment with C/T compared to CZA was 1·97 [95% CI:1·10–3·53]. Corresponding rates of success for patients with pneumonia were 63% (110/175) and 51% (89/175), respectively (aOR=2·23 [95% CI:1·17–4·26]). There were no differences in 30- or 90-day mortality rates. Resistance developed in 22% (38/173) and 23% (40/177) of patients treated with C/T and CZA, respectively. Interpretation. Treatment with C/T resulted in higher rates of clinical success comp