Susceptibility of Colistin-Resistant, Gram-Negative Bacteria to Antimicrobial Peptides and Ceragenins

ABSTRACT The susceptibility of colistin-resistant clinical isolates of Klebsiella pneumoniae to ceragenins and antimicrobial peptides (AMPs) suggests that there is little to no cross-resistance between colistin and ceragenins/AMPs and that lipid A modifications are found in bacteria with modest changes in susceptibility to ceragenins and with high levels of resistance to colistin. These results suggest that there are differences in the resistance mechanisms to colistin and ceragenins/AMPs.