Mechanism Of Action Of Antibiotics Flashcards
Name the different types of Antibiotics.
- β-lactam
- Quinolone
- Macrolide
- Aminoglycoside
- Tetracycline
How do β-lactam Antibiotics function?
- Inhibit Transpeptidase (similar structure to D-alanyl)
- Competitive inhibition
- Irreversible Binding
What are Quinolones?
Type: Bactericidal, Synthetic
Spectrum: Broad
Aim: Target Bacterial Enzymes needed for DNA replication (DNA Gyrase)
Structure:
- Bicyclic
- Quinoline backbone (Fusion of Benzene + Pyridine rings)
Examples:
- Ciprofloxacin
- Moxifloxacin
Uses: UTI, respiratory infections
What is the Quinolones Mechanism of Action?
Interfere with DNA supercoiling
- Bind to DNA Gyrase (Topoisomerase II)
- Also bind to Topoisomerase IV
- Controlled unwinding of supercoiled DNA prevented
- Forms Double stranded DNA Breaks
- Results in Cell Death
What Are Macrolides?
- Bacteriostatic Agents with Macrocyclic lactone ring
- Polyketides (Natural products)
What is the Spectrum of Activity of Macrolides?
- Against Gram+ cocci
- Staphylococci + Streptococci
Others:
- Mycobacteria
- Mycoplasmas
- Spirochetes
What is The Mechanism Of Action of Macrolides?
Antibacterial Action: Inhibit Protein Synthesis
- bind to 50s Ribosomal Unit
- inhibit translocation during elongation phase of protein synthesis
- Ribosome unable to advance along mRNA
- Peptide Chain Elongation halted
- Bacterial protein Synthesis Stopped
- bacterial Replication Blocked
Non-Antibiotic Actions:
- Disrupt bacterial communities
- Inhibit pro-inflammatory cytokines
- Reduce neutrophil recruitment to inflamed tissues
What are the Aminoglycosides?
- Bactericidal
- Amino sugars bonded by Glycosidic Bonds (Natural Products)
What is the Spectrum Of Activity of Aminoglycosides?
Gram Negative
- Streptomycin
- Kanamycin
- Tobramycin
- Gentamycin
- Neomycin
What Is The Mechanism Of Action of Aminoglycosides?
Disrupt Bacterial Protein Synthesis
- Irreversibly bind to 16S rRNA within the 30S Ribosomal subunit at A-Site
- Ribosome structure distorted, Mis-interprets mRNA codons
- Amino acids mis-incorporated in elongating peptides
- Incorporation of misfolded proteins causes membrane damage, increasing permeability, causing increased drug uptake
- Ribosome targeting and binding increases
- Causes Cell Death
What Are Tetracyclines?
- Bacteriostatic Antibac agents
- Natural products
What is The Spectrum Of Activity of Tetracyclines?
- Broad spectrum
- Work better against Gram+
Examples:
- Streptococcus pneumoniae
- Streptococcus pyogenes
- Staphylococcus aureus
What Is The Mechanism Of Action of Tetracyclines?
Inhibit Protein Synthesis
- Bind to 16S rRNA near A site
- Aminoacyl-tRNA binding to A site stopped
- tRNA unable to dock or add amino acids to growing polypeptide chain
- Elongation halted
- Bacterial Replication Arrested
