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Classification of Antibiotics: Inhibitors of Bacterial Cell Wall Synthesis
- Beta Lactams
Classification of Antibiotics: Inhibitors of Protein Synthesis
- Pleuromutilins (Retapamulin)
Classification of Antibiotics: Inhibitors of Nucleic Acid Synthesis
Classification of Antibiotics: Disruptors of Cell Membrane Permeability
- Cyclic Lipopeptides
Classification of Antibiotics: Antifolates
Classification of Antibiotics: Antituberculosis Agents
Cross Resistance can be caused by what two mechanisms?
- overlapping targets
- active efflux
What is Co-Resistance?
- Multi-drug resistance
- when several mechanisms of resistance develop against the entire class of drugs
What is the difference between a gram-positive bacterial cell wall and the gram-negative bacterial cell wall?
- Gram-Positive Bacterial Cell Wall:
- Less developed biosynthetically.
- Simple cell wall.
- High internal osmolality.
- Very thick peptidoglycan layer.
- Antibiotic agents mostly active in gram positive!
- Gram-Negative Bacterial Cell Wall:
- Highly developed biosynthetically.
- Highly adaptive (more sophisticated cell wall).
- Complex; penetration of antibiotics is often restricted.
- Low internal osmolality.
- Very thin peptidoglycan layer.
What are other names for the peptidoglycan layer?
What alternating aminosugars make up the peptidoglycan layer in the bacterial cell wall?
- N-acetylglucosamine (NAG)
- N-acetylmuramicacid (NAM)
Antibiotics inhibit different steps in the synthesis of the peptidoglycan layer in the bacterial cell wall. What are the synthesis steps for peptidoglycan?
- 1) Peptidoglycan Monomers are formed: NAG & NAM
- 2) Alanine Racemase step: A pentapeptide is attached to NAM, and the last two amino acids on that pentapeptide, which are L-alanines, are converted to D-alanines via Alanine Racemase enzyme.
- 3) Bactoprenols Transport & Insert: Bactoprenols insert the monomers into the growing peptidoglycan wall.
- 4) Transglcosylation: Glycosidic bonds are formed between NAG and NAM in the peptidoglycan layer via the transglycosidase enzyme.
- 5) Transpeptidation or Cross-Linking: Peptide bonds are formed between the layers of peptidoglycan via transpeptidase enzymes. This cross-linking makes the peptidoglycan wall strong.
What steps of peptidoglycan synthesis do antibiotics block?
- 1) Inhibit the synthesis of peptidoglycan monomers: Fosfomycin
- 2) Inhibit the Alanine Rasinase Step: Cycloserine
- 3) Inhibit the Bactoprenols from Transportation & Insertion: Bacitracin
- 4) Inhibit the Transglycosylation Step:Vancomycin, Dalbavancin, Telavancin
- 5) Inhibit the Transpeptidation or Cross-Linking Step: b-Lactams, Vancomycin, Dalbavancin, Telavancin
What are the two bifunctional penicillin binding protein (PBP) domains called?
- glycosyltransferase (membrane bound): transglycosylation step
- transpeptidase (extracellular): transpeptidation or cross-linking step