MECHANISM OF TETRACYCLINE RESISTANCE IN STAPHYLOCOCCUS AUREUS

I. INDUCIBLE RESISTANCE TO TETRACYCLINE

Abstract

This paper deals with kinetic studies on the induction of resistance to tetracycline (TC) in Staphylococcus aureus. It was found that TC-resistance is inducible and TC is an active inducer. Cell populations acquired high resistance to TC after prior exposure to subinhibitory concentrations of the drug, but the resistance of induced populations was lost when the cells were grown in the absence of inducer. Induction of TC-resistance did not take place when protein synthesis of bacteria was inhibited by addition of chloramphenicol or actinomycin D, and by histidine starvation in a histidine auxotroph. The acquisition of resistance to tetracycline was paralleled by a decrease in the accumulation of the drug in bacterial cells, resulting from a decrease in their permeability for tetracycline.