Clinical Efficacy and Safety of the Combination of Colistin plus Vancomycin for the Treatment of Severe Infections Caused by Carbapenem-Resistant <b><i>Acinetobacter baumannii</i></b>

A potent synergy of a glycopeptide-colistin combination against <i>Acinetobacter baumannii</i> has recently been described. We set out to assess the efficacy and safety of this combination in a retrospective study including episodes of ventilator-associated pneumonia or bacteremia caused by carbapenem-resistant <i>A. baumannii.</i> We compared 29 patients (group I) treated with colistin plus vancomycin with 28 patients treated with colistin alone (group II). Group I received vancomycin (for empirical or targeted therapy) at the onset of colistin administration and both antimicrobials coincided for at least 5 days. Baseline characteristics, clinical cure, microbiological eradication, and mortality were similar in both groups but the rate of acute kidney injury was higher in group I (55.2 vs. 28%; p = 0.04). In critically ill patients with carbapenem-resistant <i>A. baumannii</i> infections, clinical outcomes do not differ in patients treated with colistin plus vancomycin from those receiving colistin without vancomycin. This combination significantly increases the risk of renal failure.