Specificity and Mechanism of Tetracycline Resistance in a Multiple Drug Resistant Strain of Escherichia coli

Izaki, Kazuo (University of Tokyo, Tokyo, Japan),Kan Kiuchi, and Kei Arima . Specificity and mechanism of tetracycline resistance in a multiple drug resistant strain ofEscherichia coli . J. Bacteriol.91: 628–633. 1966.—A decrease in the uptake of tetracycline occurred concurrently with a rise in the level of resistance of a multiple drug resistant strain ofEscherichia coli grown in the presence of tetracycline. Although the strain was also resistant to streptomycin and chloramphenicol, growth in the presence of these two antibiotics did not influence the uptake of tetracycline. The induction of resistance, or decreased uptake of tetracycline, was dependent on growth of the organism in the presence of the drug. Decreased uptake of tetracycline could not be induced in a sensitive strain of the same organism under conditions suitable for induction of the resistant strain. The decrease in accumulating power of the resistant organism cultured in the presence of tetracycline does not appear to be due to selection of a resistant strain from cultures containing both resistant and sensitive strains.