Aerosolized plus intravenous polymyxin B in comparison to intravenous polymyxin B alone for the management of HAP caused by carbapenem-resistant gram-negative bacteria: A prospective multicenter cohort study

•In patients with CRO pneumonia, the administration of aerosolized and intravenous polymyxin B therapy resulted in significant reductions in APACHE II scores and procalcitonin levels.•The combination treatment did not yield statistically significant improvements in clinical outcomes or bacterial eradication compared to intravenous polymyxin B alone in patients suffering from CRO pneumonia. This study aimed to evaluate the clinical effectiveness of combined aerosolized (AER) and intravenous (IV) polymyxin B in managing patients with hospital-acquired pneumonia (HAP) caused by carbapenem-resistant gram-negative organism (CRO). This multicenter prospective cohort study was conducted across six intensive care units in municipal and above-municipal hospitals in Shaanxi, China, from January 1, 2021 to December 31, 2022. Patients with CRO pneumonia were categorized into the intravenous group (IV polymyxin B alone) and the combination group (AER plus IV polymyxin B). Primary outcomes included ICU mortality, 28-day mortality and bacterial clearance, while secondary outcomes included the duration of mechanical ventilation and length of ICU stay. A total of 64 patients were included in the study, with 29 receiving AER plus IV polymyxin B and 35 receiving IV polymyxin B alone. On the seventh day of treatment, the combination group showed a significant reduction in the APACHE II score (17.86 ± 5.03 vs. 19.17 ± 11.02, P = 0.041) and procalcitonin levels (1.27 ± 0.20 vs. 3.18 ± 0.69, P < 0.001) compared to the intravenous group. Additionally, the combination group exhibited a higher bacterial eradication rate (62.1% vs. 42.9%), lower ICU mortality (27.6% vs. 37.1%), shorter duration of mechanical ventilation (371.39 ± 68.97 h vs. 563.94 ± 100.25 h), and reduced ICU stay (34.41 ± 17.87 d vs. 35.03 ± 21.66 d), although the differences were not statistically significant. In patients with CRO pneumonia, combination therapy resulted in significant reductions in APACHE II scores and procalcitonin, but did not lead to statistically significant improvements in clinical outcomes, compared to IV polymyxin B alone. [Display omitted]