A COMPARISON OF THE INHIBITION OF TRANSLATION AND 50S-RIBOSOMAL-SUBUNIT FORMATION IN STAPHYLOCOCCUS-AUREUS CELLS BY 9 DIFFERENT MACROLIDE ANTIBIOTICS

Nine structurally similar macrolide antibiotics were tested at a conce ntration of 0.5 mu g/ml for their relative inhibitory effects on ribos ome functions in Staphylococcus aureus cells. Eight of the compounds e xamined inhibited protein synthesis at this concentration. Seven of th e nine compounds were also effective in blocking formation of the 50S ribosomal subunit. Roxithromycin and 14-hydroxy clarithromycin inhibit ed protein synthesis to a,greater extent than they affected 50S subuni t formation. Conversely, the compound 11,12-carbonate-3 deoxy-clarithr omycin affected 50S assembly mow than translation. Only clarithromycin had any effect on 30S ribosomal subunit assembly. The decline in grow th rate and cell number was proportional to the effect on ribosome for mation or function by each compound. These inhibitory activities can b e related to structural differences between these macrolide antibiotic s.