Compare intravenous colistimethate sodium (CMS) with non-CMS antibiotics in combination with nebulized CMS for treating Carbapenem-resistant Gram-negative Bacilli (CR-GNB) pneumonia: a multicenter retrospective cohort study

This study aims to assess the effectiveness and safety of treatment by combining intravenous regimens containing colistimethate sodium (CMS) with nebulized CMS compared to that combination of intravenous non-CMS antibiotics with nebulized CMS. This multicenter retrospective study from 24 hospitals in China compared two regimens: intravenous (IV) colistimethate sodium (CMS) plus nebulized CMS (study group) vs. IV non-CMS antibiotics plus nebulized CMS (control group). Outcomes included clinical response rate, bacterial eradication rate, mortality, and adverse events. Propensity score matching (1:1) was applied for primary analysis. Multivariable logistic regression using entire cohort data was conducted as a supportive analysis for the effectiveness of the study regimen. Among 427 eligible patients (215 study and 212 control), 130 matched pairs were included in the primary analysis (median age 69 vs. 71 years; male 73.9% vs. 85.4%; no prior Gram-negative bacilli (CR-GNB) infection 86.9% vs. 88.5%). Predominant pathogens were CRAB (72.9% vs. 55.3%), CRKP (9.3% vs. 19.5%), and CRPA (7.8% vs. 12.2%). The study group demonstrated a shorter nebulized CMS duration (9 vs. 11 days, p = 0.02), higher clinical response rate (82.3% vs. 70.8%, p = 0.03), and better eradication (80.6% vs. 68.5%, p = 0.03) in matched analysis. Results from entire data further supported the effectiveness with an adjusted OR 2.60 (95%CI:1.48–4.57, p = 0.001) for clinical response after controlling for potential confounding factors. Mortality and kidney injury showed no significant difference between groups. IV CMS with nebulized CMS is associated with improved clinical response against CR-GNB pneumonia versus IV non-CMS alternatives, without additional safety concerns.