Survival of carbapenem-resistant Acinetobacter baumannii bacteremia: colistin monotherapy versus colistin plus meropenem

OBJECTIVE: The aim of this study was to compare clinical outcomes between patients with carbapenem-resistant Acinetobacter baumannii (CRAB) bacteremia treated with colistin monotherapy and those treated with colistin plus meropenem. METHODS: We retrospectively evaluated data from 71 patients with CRAB bacteremia treated from November 2006 to February 2018. Predictors of 14-day mortality were determined through logistic regression analysis. RESULTS: Our study cohort included 40 bacteremia patients (44.6 %) treated with colistin monotherapy and 31 (55.4 %) treated with colistin plus meropenem. Overall 14-day mortality tended to be higher with monotherapy rather than combination therapy (47.5% vs 25.8%). The latter also showed a tendency for higher clinical success rate compared with monotherapy (61.3% vs 40.0%). Logistic regression analysis showed that Pitt bacteremia score, pneumonia, and combination therapy were significantly associated with mortality. In patients with higher Pitt bacteremia score (≥4), mortality was significantly higher with monotherapy compared with combination therapy (66.7% vs 27.8%). In patients with lower Pitt bacteremia score (≤3), mortality was similar between the two treatment groups (26.3% vs 23.1%). CONCLUSION: Treatment with colistin plus meropenem improves survival in critically-ill patients with CRAB.