Effectiveness of imipenem-relebactam for multidrug-resistant <i>Pseudomonas aeruginosa</i> in pneumonia and bloodstream infections in the United States (MIRAGE)

Imipenem-relebactam demonstrates <i>in vitro</i> activity against multidrug-resistant (MDR) <i>Pseudomonas aeruginosa</i>, but real-world effectiveness data are limited. MIRAGE was a multicenter, retrospective, observational study of imipenem-relebactam for MDR <i>P. aeruginosa</i> pneumonia and bacteremia. Patients were included if they received imipenem-relebactam for >48 h within 7 days of index <i>P. aeruginosa</i> culture. The primary outcome was clinical success at day 30, defined as survival, resolution of signs and symptoms of infection, completion of intended treatment course, and absence of recurrent infection. Secondary outcomes included 30- and 90-day mortality, infection recurrence, and development of non-susceptibility. Sixty-three patients were included. Median (IQR) age was 61 (51-70) years, and the median Charlson Comorbidity Index was 5 (3-6). Forty-six percent of patients had an immunocompromising condition, 79% were in the intensive care unit, 76% were receiving mechanical ventilation, and 48% required vasopressors. Median SOFA score was 7 (5-12). Forty percent of index isolates that were tested displayed non-susceptibility to both ceftolozane-tazobactam and ceftazidime-avibactam. Fifty-six percent of patients achieved clinical success at day 30. All-cause 30- and 90-day mortality rates were 18% and 29%, respectively. Recurrent infections were documented in 37% of patients within 90 days, and resistance developed in 39% (16/41) of evaluable patients. Clinical outcomes following imipenem-relebactam for treatment of MDR <i>P. aeruginosa</i> were comparable to those reported in real-world studies for other novel β-lactam agents. Our data suggests that imipenem-relebactam has a role in the treatment of patients infected with MDR <i>P. aeruginosa</i>.