[Relationship between bacterial envelope barrier and resistance of E. coli, S. aureus to rifamdine].

The Rifamdine (RFD) resistant strains were obtained from wild types of S. aureus NCTC 6571, E. coli NCTC 10418 and Proteus vulgaris by drug concentration gradient plate. The experiment indicated that the growth inhibition of resistant cells induced by synergism of EDTA acting with RFD. Such results did not occur effectively if EDTA or RFD was added separately. The amount of 3H-RFD incorporated into cells of susceptible and resistant strains of E. coli and S. aureus was compared. The amount of 3H-RFD incorporated into susceptible cells was much greater than that of the resistant strains in E. coli cells. Ultrastructure comparison of sensitive and resistant cells showed that the surface of resistant cells was coarser and shorter, the outer membrane thickened and electron density increased. These results have shown that there is a close relationship between the resistance of bacteria induced by RFD and the decrease in the permeability of cell envelope barrier to the drug.