Resistência Natural ou intrinseca à colistina:
The pathogenic Neisseria spp., Moraxella catarrhalis, Helicobacter pylori, Proteus mirabilis, Serratia marcescens, Morganella morganii, Chromobacterium and Brucella species are naturally resistant to colistin. In Proteus mirabilis, Burkholderia cepacia and Chromobacterium violaceum, polymyxin resistance has been associated with the changes in lipid A.