MOAs - antibiotics - basics Flashcards
What is the mechanism of action (MOA) of Penicillins?
Inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs) and preventing cross-linking of peptidoglycan, leading to osmotic lysis and bacterial death.
Example Drugs: Penicillin G, Penicillin V, Nafcillin, Oxacillin
Are Penicillins bactericidal or bacteriostatic?
Bactericidal
What are key resistance mechanisms for Penicillins?
- β-lactamase enzymes (degrade the β-lactam ring)
- Altered PBPs (e.g., mecA gene in MRSA)
What is the mechanism of action (MOA) of Aminopenicillins?
Same as penicillins (bind PBPs, inhibit peptidoglycan cross-linking) with expanded Gram-negative coverage.
Example Drugs: Amoxicillin, Ampicillin
Are Aminopenicillins bactericidal or bacteriostatic?
Bactericidal
What are key resistance mechanisms for Aminopenicillins?
- β-lactamase production (overcome with clavulanate or sulbactam)
- Porin mutations in Gram-negative bacteria
What are the generations of Cephalosporins?
- 1st Gen: Cefazolin, Cephalexin
- 2nd Gen: Cefuroxime, Cefoxitin
- 3rd Gen: Ceftriaxone, Ceftazidime
- 4th Gen: Cefepime
- 5th Gen: Ceftaroline
What is the mechanism of action (MOA) of Cephalosporins?
Same as penicillins (bind PBPs, inhibit peptidoglycan cross-linking) and more resistant to β-lactamases than penicillins.
Are Cephalosporins bactericidal or bacteriostatic?
Bactericidal
What are key resistance mechanisms for Cephalosporins?
- Extended-Spectrum β-lactamases (ESBLs) in resistant Gram-negative bacteria
- Altered PBPs (seen in MRSA, except ceftaroline)
What is the mechanism of action (MOA) of Carbapenems?
Same as penicillins (bind PBPs, inhibit peptidoglycan cross-linking) and have a very broad spectrum, including ESBL-producing Gram-negatives and anaerobes.
Example Drugs: Imipenem, Meropenem, Ertapenem
Are Carbapenems bactericidal or bacteriostatic?
Bactericidal
What are key resistance mechanisms for Carbapenems?
- Carbapenemases (KPC, NDM-1, OXA-48) in highly resistant bacteria
- Efflux pumps in some Pseudomonas strains
What is the mechanism of action (MOA) of Glycopeptides?
Inhibits bacterial cell wall synthesis by binding D-Ala-D-Ala residues of peptidoglycan precursors, preventing cross-linking and leading to cell death.
Example Drug: Vancomycin
Are Glycopeptides bactericidal or bacteriostatic?
Bactericidal
What are key resistance mechanisms for Glycopeptides?
VanA gene in VRE (Vancomycin-Resistant Enterococcus) changes D-Ala-D-Ala → D-Ala-D-Lac, preventing drug binding.
What is the mechanism of action (MOA) of Fluoroquinolones?
Inhibit DNA gyrase (Topoisomerase II) and Topoisomerase IV, preventing bacterial DNA replication, leading to DNA damage and cell death.
Example Drugs: Ciprofloxacin, Levofloxacin, Moxifloxacin
Are Fluoroquinolones bactericidal or bacteriostatic?
Bactericidal
What are key resistance mechanisms for Fluoroquinolones?
- Mutations in DNA gyrase or Topoisomerase IV prevent binding
- Efflux pumps remove the drug from bacterial cells
What is the mechanism of action (MOA) of Macrolides?
Bind to the 50S ribosomal subunit, blocking bacterial protein synthesis and preventing translocation of the ribosome.
Example Drugs: Azithromycin, Clarithromycin, Erythromycin
Are Macrolides bactericidal or bacteriostatic?
Bacteriostatic
What are key resistance mechanisms for Macrolides?
- Methylation of 50S ribosomal subunit (prevents drug binding)
- Efflux pumps remove the drug from the cell
What is the mechanism of action (MOA) of Tetracyclines?
Bind to the 30S ribosomal subunit, blocking tRNA attachment to the ribosome, inhibiting bacterial protein synthesis.
Example Drugs: Doxycycline, Minocycline, Tetracycline
