Question

Please describe 6 ways that antimicrobial drugs can target pathogens.

Answer 1

There are 5 ways in which antimicrobial drugs can target pathogens which are:

1. Inhibition of cell wall synthesis

i) beta lactams- inhibtion of peptidoglycan synthesis.

ii) vancomycin - disrupts peptidoglycan linkage.

iii) bacitracin - disrupts movement of peptidoglycan precursors only have topical use.

iv) antimycobacterial agents - prevents mycolic acid and aminoglycan synthesis.

2. Inhibition of proteins synthesis

30 S ribosomal site

i) aminoglycosides - irreversibly binds 30 S ribosomal proteins.

ii)tetracyclins - blocks tRNA binding to ribosome mRNA complex.

50S ribosomal site

i) Chloramphenicol -Binds peptidyl transferase component of 50S ribosome, blocking peptide elongation

ii) Macrolides - Reversibly bind 50S ribosome, block peptide elongation.

iii)Clindamycin -Binds 50S ribosome, blocks peptide elongation; Inhibits peptidyl transferase by interfering with binding of amino acid-acyl-tRNA complex. l

3. Alteration of Cell Membranes

i) Polymyxins (topical) - Cationic detergent-like activity (topical use)

ii)Bacitracin (topical) - Disrupt cytoplasmic membranes

4. Inhibition of Nucleic Acid Synthesis

DNA effects

i)Quinolones - Inhibit DNA gyrases or topoisomerases required for supercoiling of DNA; bind to alpha subunit

ii) Metronidazole - Metabolic cytotoxic byproducts disrupt DNA

RNA effects(Transcription)

i) Rifampin - Binds to DNA-dependent RNA polymerase inhibiting initiation & Rifabutin of RNA synthesis

ii) Bacitracin (topical) ---> Inhibits RNA transcription.

5.Antimetabolite Activity

i) Sulfonamides & Dapsone - Compete with p-aminobenzoic acid (PABA) preventing synthesis of folic acid

ii)Trimethoprim - Inhibit dihydrofolate reductase preventing synthesis of folic acid