Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis 0 S ·Cephalosporins R-C-NH-CH-CH CH2 0 O=C一N C-CH2-0-C 。2nd,3rd,and4h CH3 generations more COOH effective against Cephalosporin nucleus gram-negatives 0 S、/cH3 R-C-NH-CH-CH CH3 O=C一N一CH-COOH Penicillin nucleus Figure 20.9 • Cephalosporins • 2 nd, 3rd, and 4th generations more effective against gram-negatives Antibacterial Antibiotics Inhibitors of Cell Wall Synthesis Figure 20.9