Old Polymyxins Are Back: Is Resistance Close?

Abstract

TOTHE EDITOR—Recently, there has been substantial rekindled interest in polymyxins (mainly polymyxin B and colistin; colistin will be used as the representative in this letter), which were replaced in the 1970s by antibiotics that were believed to be less toxic [1]. Significant, worldwide medical concern regarding multidrug-resistant, gram-negative “superbugs”—in particular, Pseudomonas aeruginosa and Acinetobacter baumannii—and a dry antibiotic development pipeline have highlighted the urgent need for novel antibiotics [2, 3]. We are fortunate to have this “reserved” old class of polymyxin antibiotics available to use as salvage therapy. Recent clinical reports have demonstrated the effectiveness and acceptable safety of this last-line antibiotic [4–6]. However, because of the lack of pharmacokinetic and pharmacodynamic data, the dosage regimens being used are potentially suboptimal. For this reason, it may not be too early to ask: how far away is widespread resistance to colistin?