Efficacy and safety of intravenous combined with aerosolized colistimethate sodium for carbapenem-resistant organism-induced pneumonia: a retrospective study

Polymyxins are regarded as the last-resort antibiotics for treating resistant Gram-negative bacteria. Colistimethate sodium (CMS) is commonly used for carbapenem-resistant organism (CRO)-induced pulmonary infection. However, the polycationic/hydrophilic structure of intravenous injection (IV-CMS) limits its penetration into lung parenchyma, whereas aerosol inhalation (AER-CMS) has high alveolar penetration and minimal systemic dispersion. Currently, post-marketing monitoring of the clinical efficacy and safety of IV + AER CMS is limited. We aimed to evaluate the efficacy and safety of IV + AER CMS (Tianyun ® ; Chiatai Tianqing Pharma Jiangsu, China) in the treatment of CRO-induced pulmonary infections. This is a multi-center retrospective study. Patients with CRO-induced pulmonary infection who received IV + AER CMS/IV-CMS alone between 2021 and 2023 were enrolled. The primary endpoint was clinical response rate, and secondary endpoints included clinical cure rate, length of stay, mortality, and incidence of adverse events (pigmentation, hypersensitivity, renal toxicity, neurotoxicity, and bronchospasm). There were 101 patients in IV + AER CMS group and 108 patients in IV-CMS group. The clinical response rate in IV + AER CMS group was significantly higher than that in IV-CMS group (78.57% vs. 60.00%, p = 0.017). There were no significant differences in clinical cure rate, length of stay and 28-day all-cause mortality between two groups. No significant differences in the incidence of adverse events were observed between two groups. The clinical response rate of IV + AER CMS for CRO-induced pulmonary infection is higher than that of IV-CMS and no increased risk of renal toxicity, demonstrating good tolerability of AER-CMS in clinical practice.