Colistin for pneumonia involving multidrug-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex

Objectives: To investigate clinical and microbiological response, and 30-day mortality of pneumonia involving multidrug-resist ant (MDR) Acinetobacter calcoaceticusAcinetobacter baumannii (Acb) complex treated with colistin, and identify associated factors of these outcomes. Methods: A retrospective study of 183 adult patients with colistin treatment for at least 7 days between January 2014 and October 2017. Results: The mean age was 76.8 years, and mean Acute Physiology and Chronic Health Evaluation II score was 17.7. Eighteen (9.8%) and 128 (69.9%) patients had intravenous (IV) colistin alone and inhaled (IH) colistin alone, respectively. Thirty-seven patients had both IV and IH colistin, including 5 (2.7%) with concurrent, and 32 (17.5%) with non-concurrent use of IV and IH colistin. The 30-day mortality rate was 19.1% and 131 (71.6%) patients had clinical response. In the 175 patients with available data, 126 (72%) had microbiological eradication. The multivariate analyses revealed that IH colistin alone was an independent predictor for 30-day survival, clinical response, and microbiological eradication, and IV colistin alone was an independent predictor for clinical failure. Patients with IV colistin alone had a significantly higher nephrotoxicity rate than IH colistin alone (37.5% vs 6.1%, P = 0.001). Sub-group analysis of 52 patients with IV colistin for S 4 days revealed that 14 (26.9%) patients had inappropriate dose, and inappropriate dose was an independent predictor for 30-day mortality. Conclusions: IH colistin provided good outcomes with few side effects, and appropriate dosing of IV colistin was important to avoid excess mortality. Copyright (C) 2019, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC.