Micro Lecture 13: Antimicrobial Drugs

Cell wall synthesis target

Prevents proper construction or cross-linking of peptidoglycan. Without cross linking, the cell becomes more susceptible to rupture.

Examples: penicillins, cephalosporins, vancomycin, bacitracin.

Protein synthesis target

Interferes with bacterial ribosomes and translation.

Examples: tetracyclines, aminoglycosides, macrolides, chloramphenicol.

Plasma membrane integrity target

Damages the membrane, disrupting its essential functions.

Example: polymyxin B.

Nucleic acid synthesis target

Blocks DNA replication or RNA transcription.

Examples: quinolones/fluoroquinolones, rifampin.

Metabolic pathways

Blocks the production of folic acid, which bacteria need to synthesize essential molecules.

Example: sulfonamides.

Specialized cell wall components pathways

Targets mycolic acid synthesis or incorporation in mycobacteria.

Examples: isoniazid and ethambutol.

What are two major disadvantages to natural penicillin?

It has a low spectrum, and is suscpetible to B-lactamases, which break down penicillin.

What are some of the advantages of cephalosporins?

They are effective against more gram-negative bacterium, are resistant to enzymes, and can cross the blood-brain barrier.

What is Bacitracin?

Bacitracin is found in Neosporin and is used topically.

Vancomycin is found in:

MRSA

What are Ethambutol and Isoniazid used for?

These two drugs are used for fighting certain mycobacterium.

What two drugs target 50S ribosomes?

Chloramphenicol (broad spectrum with severe bone marrow side effects) and macrolides (

Tetracycline

MUST KNOW: broadest spectrum drug in the lecture, and interferes with tRNA attachment.

Aminoglycosides

Initiation complex formation

Drugs that damage the plasma membrane

Polymyxin B. Is it BACTERICIDAL

Top DNA interfering drug?

Rifamycin, which actually blocks transcription (RNA polymerase)

What do quinolones and fluiroquinolones do?

They inhibit DNA gyrase

What do sulfanomides do?

Sulfanomides affect metabolism. They are broad spectrum, bacteriostatic, and inhibitors or folic acid. These specifically block the PABA pathway.

What are the three drugs that treat fungal infections?

Polyenes, azoles, echinocandins

Polyenes

Polyenes target the membrane of the cell

Azoles

Azoles inhibit ergosterol synthesis; ergosterol is

Echinocandins

These target the cell wall, and inhibit the synthesis of B-glucan