Antimicrobial peptides (APs) impose a threat to the survival of pathogens, and it is reasonable to postulate that bacteria have developed strategies to counteract them. Polymyxins are becoming the last resort to treat infections caused by multidrug-resistant Gram-negative bacteria and, similar to APs, they interact with the anionic lipopolysaccharide. Given that polymyxins and APs share the ini...

Escherichia coli Ec36 was recovered from a patient in Portugal after treatment with meropenem and colistin. Besides an IncF plasmid with Tn1441d-blaKPC-3, already reported in clinical strains in this country, E. coli Ec36 co-harbored an IncX4::mcr-1 gene. Results highlight emerging co-resistance to carbapenems and polymyxins after therapy with drugs from both classes.

In a recent article, Garonzik et al. (4) importantly advanced our knowledge of the pharmacokinetics (PK) of colistin methanesulfonate (CMS) and the active drug that it forms, colistin. In their elegant population PK study of critically ill patients, the authors demonstrated that creatinine clearance (CLCR) significantly affects the total body clearance of CMS and colistin (4). It is important t...