Antibacterial Agents Flashcards
What are the three types of antibacterial agents?
- Antibiotics: Natural products (e.g., Penicillin). 2. Semisynthetic agents: Modified natural compounds (e.g., Cephalosporins). 3. Synthetic agents: Fully laboratory-produced (e.g., Quinolones).
Name two examples of semisynthetic antibacterial agents.
Cephalosporins and Carbapenems.
What does selective toxicity in antibacterial therapy mean?
It targets microorganisms without harming human tissues.
What is the difference between bactericidal and bacteriostatic drugs?
Bactericidal: Kills bacteria (e.g., Beta-lactams). Bacteriostatic: Inhibits bacterial growth, allowing the immune system to act (e.g., Tetracyclines).
Which bacteria produce β-lactamases that degrade β-lactam antibiotics?
Enteric bacteria like E. coli, Klebsiella, and Proteus.
What is the mechanism of resistance for Methicillin-resistant Staphylococcus aureus (MRSA)?
It produces PBP2A through the mecA gene, conferring resistance to β-lactam antibiotics.
What is the main treatment for MRSA?
Vancomycin.
What are the main inhibitors of cell wall synthesis?
Beta-lactams (e.g., Penicillins, Cephalosporins) and Vancomycin.
Which enzyme is inhibited by Quinolones, affecting DNA synthesis?
DNA gyrase (topoisomerase).
What is the action mechanism of Rifampicin?
It inhibits RNA synthesis by binding to DNA-dependent RNA polymerase.
What is co-trimoxazole?
A combination of Sulfonamide and Trimethoprim, inhibiting folic acid synthesis.
How does Vancomycin resistance occur in some bacteria?
By changing the peptidoglycan component from D-alanyl-D-alanine to D-alanine-D-lactate.
What causes multi-resistance in bacteria?
Resistance to more than two antibacterial families through different mechanisms.
Which tests are used for antibiotic sensitivity testing (AST)?
- Tube dilution test (determines MIC). 2. Disk diffusion test (Kirby-Bauer method).
