Lipid alterations in cell envelopes of polymyxin-resistant Pseudomonas aeruginosa isolates.
The lipid composition of cells of Pseudomonas aeruginosa strains resistant to polymyxin was compared with the lipid composition of cells of polymyxin-sensitive strains as to their content of readily extractable lipids (RELs), acid-extractable lipids, the fatty acid composition of RELs, and the contents of various phospholipids in the REL fraction. The polymyxin-resistant strains had an increased content of RELs, but a decreased phospholipid content. The REL fraction from the polymyxin-resistant strains had an increased content of unsaturated fatty acids accompanied by a decreased content of cyclopropane fatty acids as compared with the fatty acid composition of RELs from polymyxin-sensitive strains. The phosphatidylethanolamine content was greatly reduced in the polymyxin-resistant strains, whereas the content of an unidentified lipid, thought to be a neutral lipid lacking either a phosphate, free amino, or choline moiety, was greatly increased. Cell envelopes of the polymyxin-resistant strains contained reduced concentrations of Mg2+ and Ca2+ as compared with the cell envelopes of polymyxin-sensitive strains. It appears that polymyxin resistance in these strains is associated with a significant alteration in the lipid composition and divalent cation content of the cell envelope.
D004352:Drug Resistance, Microbial; D005227:Fatty Acids / Q000032:analysis; D005231:Fatty Acids, Unsaturated / Q000032:analysis; D008563:Membrane Lipids / Q000032:analysis*; D010743:Phospholipids / Q000032:analysis; D011112:Polymyxin B / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000032:analysis* / Q000187:drug effects
D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008563:Membrane Lipids; D010743:Phospholipids; D011113:Polymyxins; D011112:Polymyxin B