Impact of Antimicrobial Therapy on Mortality and Readmission in Multidrug-Resistant Pseudomonas Infections: A Retrospective Study at Dammam Medical Complex.

Multidrug-resistant (MDR) Pseudomonas aeruginosa presents a significant treatment challenge, necessitating effective antimicrobial options. This retrospective, single-center cohort study was conducted at Dammam Medical Complex and aimed to evaluate the comparative effectiveness and safety of ceftazidime-avibactam (CAZ-AVI), ceftolozane-tazobactam (C-T), and meropenem and colistin in treating MDR P. aeruginosa infections. The study included 250 patients (n = 250, 100%) admitted between January 2022 and November 2024, who were treated with one of the three antimicrobials. The primary outcomes assessed were clinical cure, 30-day mortality, and all-cause in-hospital mortality. Secondary outcomes included readmission rates within 30 days and the rate of uncontrolled infection by day 14 (n = 40, 16%). The patient cohort consisted of a mix of ICU admissions (n = 138, 55.2%), mechanically ventilated patients (n = 140, 56%), and those requiring vasopressors (n = 100, 40%). Most patients were elderly with multiple pre-existing medical conditions, such as diabetes (n = 175, 70%), hypertension (n = 88, 35.2%), and chronic kidney disease (n = 63, 25.2%). Results demonstrated that ceftazidime-avibactam was associated with a statistically significant higher clinical cure rate (n = 180, 72%) compared to ceftolozane-tazobactam (n = 44, 59%) and meropenem and colistin (n = 24, 48%) (P < 0.05). Similarly, patients treated with CAZ-AVI had significantly lower readmission rates within 30 days compared to those on C-T or meropenem and colistin. The overall in-hospital mortality was highest among patients treated with meropenem and colistin (n = 19, 38%), followed by C-T (n = 24, 32%), and lowest with CAZ-AVI (n = 30, 24%) (P < 0.05). The findings suggest that ceftazidime-avibactam is more effective in achieving clinical cure and reducing readmission rates compared to ceftolozane-tazobactam and meropenem and colistin in patients with MDR P. aeruginosa infections. Meropenem and colistin were primarily used when supply constraints limited the availability of other agents, highlighting the need for improved access to preferred antimicrobials. These results underscore the importance of optimized antimicrobial stewardship in the management of MDR P. aeruginosa to improve patient outcomes.