[Effect of magnesium ions on Staphylococcus aureus sensitivity to streptomycin]

The causes of the protective effect of magnesium ions on sensitivity of Staphylococcus aureus to aminoglycosides were studied. It was found that the cation effect on accumulation of the biomass in the presence of streptomycin was first of all due to a decrease in the capacity of the bacterial cells to accumulate the antibiotic because of blocking the antibiotic receptors on the cell wall surface. The nature of the receptors is discussed. Possible participation of the teichoic acid phosphate groups in streptomycin binding to the cell surface is suggested. The suggestion was confirmed by experiments on elimination of the polymers from the cell wall preparation.