Classification(According to their mechanism of actions 1. Inhibit the biosynthesis of bacterial cell walls(b-lactam) 2. React with cell membrances(polymycin) 3. Disturber with the biosynthesis of protein(aminoglycosides) Inhibit the replication and transcription of nucleonic acid (Nalicixic acid)Classification (According to their mechanism of actions 1. Inhibit the biosynthesis of bacterial cell walls (β –Lactam) 2. React with cell membrances (Polymycin) 3. Disturber with the biosynthesis of protein (Aminoglycosides) 4. Inhibit the replication and transcription of nucleonic acid (Nalicixic acid)