Lipid composition of Escherichia coli in relation to resistance to penicillin

Publisher Website
Google Scholar
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 the other fatty acids. Gas-chromatographic analysis of the polar-bound lipids showed an increase of the β-hydroxydecanoic acid in the resistant strains.By studying the uptake of 14C-labelled benzylpenicillin and the crypticity of the β-lactamase, evidence has been produced that a decreased permeability of resistant strains to penicillin cooperates with β-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.