High-Loading-Dose Colistin with Nebulized Administration for Carbapenem-Resistant Acinetobacter baumannii Pneumonia in Critically Ill Patients: A Retrospective Cohort Study

Carbapenem-resistant Acinetobacter baumannii (CRAB) infections pose a serious threat, with high morbidity and mortality rates. This retrospective cohort study, conducted at Nakornping Hospital between January 2015 and October 2022, aimed to evaluate the efficacy and safety of a high loading dose (LD) of colistin combined with nebulized colistin in critically ill patients with CRAB pneumonia. Of the 261 patients included, 95 received LD colistin, and 166 received LD colistin with nebulized colistin. Multivariate Cox regression analysis, adjusted for baseline covariates using inverse probability weighting, showed no significant difference in 30-day survival between patients who received LD colistin and those who received LD colistin with nebulized colistin (adjusted hazard ratio [aHR]: 1.17, 95% confidence interval [CI]: 0.80-1.72, p = 0.418). Likewise, there were no significant differences in clinical response (aHR: 0.93, 95% CI: 0.66-1.31, p = 0.688), microbiological response (aHR: 1.21, 95% CI: 0.85-1.73, p = 0.279), or nephrotoxicity (aHR: 1.14, 95% CI: 0.79-1.64, p = 0.492) between the two treatment groups. No significant adverse events related to nebulized colistin were reported. These findings suggest that the addition of nebulized colistin may not offer additional benefits in terms of 30-day survival, clinical or microbiological response, or nephrotoxicity in these patients.