抄録
Electron-microscopic and biochemical studies on motphological changes in Staplrylococcus aureus following exposure to protein synthesis inhibitory agents such as lineomycin (LCM), clindamycin (CLM), eiythromycin (EM), and spiramycin (SP) are presented in this paper. It was demonstrated that bacterial cell walls beeanne extremly thickened usually with the formation of multilayers, when exposed to eaeh of the ahove-mentioned antibiotics. Furthermorc. electron density of the cytoplasm was higher in thosc cells exposed to drugs than in intact control cells. Incorporations of 41C-labeled L lysine into the cell-wall fraction and the protein fraction were measured for biochemical elucidation of these phenomena. Labeled lysine was selectively incorporated into the cell-wall fraetion when the test organism was exposed to the respective antibiotics. Uptake at 15min after exposure was about twice as large as that of intact control cells. SP and CLM inhibited protein synthesis while they stimulated cell-wall synthcsis. The evidences for thickening of, and formation of multilaycrs in the bacterial cell walls following exposure to drugs were elosely related to the slimulating action of these antibiotics on the cell-wall synthesizing system. Morphology of resistant clinical isolates following such antibiotic exposure was also investigated using two staphyloeoccal strains, one resistant to EM alone and the other completcly cross-resistant to all the macrolides.
