title: Lipid composition of Escherichia coli in relation to resistance to penicillin.
abstract: Clinical isolates of Escherichia coli sensitive and resistant to penicillin were compared in lipid composition and 14C-labelled penicillin uptake, as possible factors in resistance. Except for a slight increase in the triglyceride fraction in sensitive strains there were no qualitative or quantitative differences in the classes of extractable lipids present. Gas-liquid chromatography of the phospholipid and triglyceride fatty acids of the polar and non-polar fatty acids of the bound lipids showed that the same kinds of fatty acids were present. There was an increase of myristate in the chloroform-methanol extractable lipids of highly resistant strains accompanied by a rather general decrease of other fatty acids. Gas-chromatographic analysis  of the polar-bound lipids showed an increase of the beta-hydroxydecanoic acid in the resistant strains. By studying the uptake of 14C-labelled benzylpenicillin and the crypticity of the beta-lactamase, evidence has been produced that a decreased permeability of resistant strains to penicillin cooperates with beta-lactamase to induce a high level of resistance. The altered lipid metabolism may reflect the special architectural changes in the cell wall which cause decreased permeability.
mesh_terms: D002463:Cell Membrane Permeability; D002509:Cephaloridine / Q000494:pharmacology; D004926:Escherichia coli / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis; D008055:Lipids / Q000032:analysis*; D010400:Penicillin G / Q000378:metabolism; D010403:Penicillin Resistance; D010405:Penicillinase / Q000096:biosynthesis; D010406:Penicillins / Q000494:pharmacology; D013045:Species Specificity
chemical_list: D005227:Fatty Acids; D008055:Lipids; D010406:Penicillins; D010405:Penicillinase; D002509:Cephaloridine; D010400:Penicillin G