CH2 | Cell Wall Inhibitors Flashcards
List beta-lactam antibiotics.
- Penicillins.
- Cephalosporins.
- Carbapenems.
- Monobactams.
What is the bacterial cell wall composed of?
Peptidoglycan strands (polymer of glycan units joined to each other by peptide cross-links).
What condition must bacteria meet for cell wall inhibitors to work?
Actively proliferating bacterial cells.
Gram-positive bacteria Vs. Gram-negative bacteria.
G+: Thick peptidoglycan layer.
G-: Thin peptidoglycan layer / Outer membrane with porins.
How do penicillins work?
Penicillins bind to PBPs, inhibiting transpeptidase enzymes needed for peptidoglycan cross-linking. This weakens the bacterial cell wall, leading to cell death.
Are cell wall inhibitors bacteriostatic or bactericidal?
Bactericidal.
What are the two natural penicillins?
- Penicillin V.
- Penicillin G.
Penicillin V is available…
Orally only.
Penicillin G is available…
Parenterally only.
Natural Penicillins Antibacterial Spectrum
- Gram+
- Gram-
- Spirochetes.
- Anaerobes.
All types of penicillins are facing increasing resistance due to…
Bacterial beta-lactamase production.
Natural penicillins are the drug of choice for…
- Gas gangrene (Clostridium perfringens).
- Syphilis (Treponema pallidum).
What are the two semisynthetic/amino/extended spectrum penicillins?
- Ampicillin.
- Amoxicillin.
Semisynthetic Penicillins Antibacterial Spectrum
- Gram+
- (((EXTENDED))) Gram-
- Spirochetes.
- Anaerobes.
Semisynthetic penicillins are the drug of choice for…
- Respiratory infections.
- Prevention of endocarditis in high-risk dental patients.
Semisynthetic penicillins must be administered with…
Beta-lactamase inhibitors:
- Clavulanic acid.
- Sulbactam.
What are the three antistaphylococcal penicillins?
- Methicillin.
- Nafcillin.
- Oxacillin.
Which type of penicillins is beta-lactamase resistant?
Antistaphylococcal penicillins (methicillin, naficillin, oxacillin).
Antistaphylococcal Penicillins Antibacterial Spectrum
- Restricted to gram-positive penicillinase producing staphylococci, including (((MSSA))).
- No activity against gram-positive organisms!!!
Antistaphylococcal penicillins are resistant to…
MRSA.
What is the only antipseudomonal penicillin?
Piperacillin.
Antipseudomonal Penicillins Antibacterial Spectrum
- Inherent antipseudomonal activity, especially against (Pseudomonas aeruginosa).
- Can be extended to include pencillinase-producing (Enterobacteriaceae) and (Bacteroides species) by using the beta-lactam inhibitor (tazobactam).
How can piperacillin’s spectrum be extended to include (Enterobacteriaceae) and (Bacteroides species)?
By coadministering it with the beta-lactamase inhibitor (tazobactam).
What are the three resistance mechanisms to penicillins?
- Beta-lactamase production.
- Decreased drug permeability.
- Modified PBPs.