A Comparative Study of High-Dose Colistin Administration for the Management of Multidrug-Resistant Gram-Negative Infections in the ICU

The aim of this study was to assess the clinical and microbiological efficacy and toxicity of different high-dose regimens of colistin in the ICU patients with colistin-sensitive MDR Gram-negative infections. In this prospective, open label, randomized clinical trial, patients with clinical features of infection and positive culture for MDR colistin-sensitive Gram-negative bacteria were randomly allocated to receive colistin, 3 or 9 million units every 8 and 24 hours, (groups A and B), respectively. For each dose regimen, clinical and microbiological response, the rates of nephrotoxicity, and its risk factors were analyzed. Forty-three patients were enrolled, and 35 completed the study protocol, of whom 30 (88.2%) had ventilator-associated pneumonia (VAP) and 5 (14%) had bacteremia. Although there were no statistically significant differences in the clinical or microbiological response between the study groups, the microbiological response favored the divided dose group numerically (p=0.40). Clinical response was achieved in 27 of 35 (77.1%) patients (p=0.999). Twelve (34.28%) patients developed AKI during colistin treatment, 4 and 8 in groups A and B, respectively (p value =0.193). Significant risk factors for nephrotoxicity related to colistin were age, hyperbilirubinemia, and coadministration of other nephrotoxic agents. In multivariate regression analysis, the only independent risk factor for CMS-associated AKI was hyperbilirubinemia (p value =0.008). Although the clinical and microbiological responses to colistin administration were not statistically different in two groups, the microbiological response favored the divided dose regimen group numerically. We did not observe any significant safety concerns with high-dose colistin administration in this population