Editorial Commentary: Optimal Usage of Colistin: Are We Any Closer?

(See the Major Article by Dalfino et al on pages 1771–7.) Despite being the mainstay of treatment for carbapenem-resistant gram-negative bacilli for more than a decade, optimal strategies for dosing and administration of colistin remain unclear. Colistin dosing regimens vary considerably throughout the world. In some instances, the total daily dose delivered varies 2-fold depending on geography. Compounding the issue is the fact that the majority of dosing strategies currently utilized were developed in the absence of accurate pharmacokinetic and pharmacodynamic data. Further complicating the issue of colistin dosing is the issue of nephrotoxicity, which often limits the dose and duration of therapy. Although many risk factors for acute kidney injury (AKI) with colistin have been identified, data supporting protective factors mitigating this dose-limiting side effect are lacking. In 2011, Garonzik and colleagues published interim results from a pharmacokinetic study that described colistin exposures in critically ill patients and, for the first time, provided pharmacokinetically based dosing recommendations [1]. The authors demonstrated the need for a loading dose and developed a dosing equation for colistin. In this issue of Clinical Infectious Diseases, Dalfino and colleagues describe their experience using this dosing algorithm and its impact on the incidence of AKI [2].