Efficacy and safety of polymyxin B sulfate versus colistin sulfate in ICU patients with nosocomial pneumonia caused by carbapenem-resistant Acinetobacter baumannii: a multicenter, propensity score-matched, real-world cohort study.

Background: Despite the widespread use of colistin sulfate (CS) in clinical settings in China over recent years, supported by several studies demonstrating its clinical efficacy, there remains a lack of comparative data on the efficacy and safety of polymyxin B sulfate (PMB) versus CS, specifically for carbapenem-resistant Acinetobacter baumannii (CRAB)-caused nosocomial pneumonia.

Objective: To compare the efficacy and safety of PMB and CS in intensive care unit (ICU) patients with nosocomial pneumonia caused by CRAB.

Methods: We conducted a multicenter retrospective cohort study, including patients diagnosed with CRAB-caused nosocomial pneumonia and treated with intravenous PMB or CS in the ICU of the study hospitals between January 1, 2020, and June 30, 2024. Propensity score matching (PSM) was employed to adjust for potential baseline confounders between cohorts. Multivariate logistic regression analysis and Cox logistic regression analyses were performed to identify for factors potentially influencing the clinical outcomes and adverse events.

Results: Following matching, a total of 190 patients were analyzed. There was no statistical significance in the rates of clinical success, microbiological eradication and 28-day mortality between the PMB and CS cohorts. While the incidence of acute kidney injury (AKI) and hepatotoxicity were comparable in both cohorts, but dermal toxicity was significantly higher in patients receiving PMB compared to those receiving CS (18.9% vs. 0%, P < 0.05). Among all the patients, hypertension, baseline renal insufficiency, usage of vasoactive drugs and in combination with three or more antibiotics were independent risk factors associated with AKI; while age, duration of polymyxins ≤ 7 days and Sequential Organ Failure Assessment (SOFA) score were risk factors associated with 28-day all-cause mortality.

Conclusion: This study establishes that PMB and CS have similar efficacy in treating CRAB induced nosocomial pneumonia in the ICU settings. The incidence of AKI and hepatotoxicity of both polymyxins are comparable for both polymyxins, although PMB is associated with a significantly higher incidence of skin toxicity. Ensuring adequate therapy duration is key to better outcomes in the treatment of CRAB-induced nosocomial pneumonia in ICU patients, regardless of the type of polymyxins.