Colistin treatment in carbapenem-resistant Acinetobacter baumannii pneumonia patients: Incidence of nephrotoxicity and outcomes

Colistimethate sodium (CMS) is increasingly used to treat multidrug-resistant Gram-negative bacilli infections. However, the incidence of CMS-associated nephrotoxicity has not been evaluated in patients with carbapenem-resistant Acinetobacter baumannii (CRAB) pneumonia. This retrospective study included 120 patients with CRAB pneumonia treated with intravenous CMS for ≥72 h. The objective of the study was to determine risk factors for CMS-induced nephrotoxicity and 30-day mortality in patients with CRAB pneumonia. Of the 120 patients with CRAB pneumonia, 61 (51%) developed nephrotoxicity. Multivariate analysis showed that dose per ideal body weight (IBW) [odds ratio (OR) = 1.28, 95% confidence interval (CI) 1.01-1.62; P = 0.04], Charlson co-morbidity index (OR = 1.31, 95% CI 1.06-1.60; P = 0.01) and septic shock (OR = 3.16, 95% CI 1.32-7.60; P = 0.01) were associated with CMS-associated nephrotoxicity. Thirty-day mortality was 33% (39/120). Multivariate analysis showed that higher daily doses of CMS per IBW [hazard ratio (HR) = 0.81, 95% CI 0.67-0.98; P = 0.03] and longer duration of CMS therapy (HR = 0.86, 95% CI 0.79-0.95; P = 0.002) were associated with increased survival. Septic shock (HR = 3.91, 95% CI 1.95-7.83; P < 0.001) and corticosteroid use (HR = 3.49, 95% CI 1.67-7.28; P = 0.001) were associated with decreased survival in patients with CRAB pneumonia. Higher daily doses of CMS per IBW, Charlson comorbidity index and septic shock were significant risk factors for CMS-associated nephrotoxicity. However, CMS-associated nephrotoxicity does not appear to have an impact on mortality.