Anti-Bacterial Drugs

Examples of agents and their actions

       

a.   Sulfonamides  -  Metabolic Pathway 

1).  Inhibits synthesis folic acid by competitive inhibition

2).  Similar in structure to PABA – substrate for folic synthesis     3).        Sulfa drugs compete with PABA for active site on enzyme

4)   Sulfa drugs react with active site on enzyme

5).  Inhibits enzyme and folic acid synthesis

6).  Bacteriostatic

                                         

b.   Penicillin - Cell Wall Synthesis   

     1).   Binds to & inhibits enzyme – penicillin-binding proteins

2).  Inhibits formation peptide (amino acid) cross bridges

3).  Inhibits formation bond between amino acid & muramic acid

4).  Weakens cell wall ® lysis bacterial cell

5).  Bactericidal

                                         

c.   Erythromycin  –  Protein Synthesis 

1).  Binds to bacterial ribosome (protein)

2).  Inhibits translocase – catalyzes movement codons (mRNA) on active site ribosome

3).  “Freezes” mRNA on ribosome

4).  Stops synthesis of protein (enzymes)

5).  Bacteriostatic

                                         

D.  Tetracyclines  -  Protein Synthesis 

 1). Binds to bacterial ribosome

2).  Blocks attachment tRNA-amino acid to ribosome-mRNA

3).  Amino acid not added to a.a. chain(protein)

4).  Stops protein synthesis

5).  Bacteriostatic

e.   Chloramphenicol  -  Protein Synthesis  

      1).  Binds to bacterial ribosome – transferase

      2).  Prevents transfer of a.a on tRNA  to a.a. chain

3).  Stops protein synthesis

4).  Bacteriostatic

f.    Streptomycin  -  Protein synthesis

1).  Binds to active site on ribosome

2).  Distorts active site on ribosome ® misreading

3).  Wrong a.a. bonded together

4).  Nonsense protein (nonfunctional) protein produced

5).  Bactericidal

g.   Quinolones  -  DNA  Synthesis 

1).  Inhibits DNA gyrase (produced by prokaryotic cells)

2).  Prevents replication bacterial DNA

h.   Rifampin  -  RNA Synthesis

  1).        Inhibits RNA polymerase (produced by prokaryotic cells)

  2)         Prevents transcription (synthesis mRNA)