Packet 2 Flashcards
What are some drugs in the beta-lactam group?
Penicillins (large group)
Cephalosporins
Carbapenems
Monobactams
What are some other cell wall synthesis inhibitors that are not beta-lactams?
Vancomycin Bacitracin Cycloserine Polymyxins Fosfomycin Daptomycin Telavancin
What are some beta-lactamase inhibitors?
Clavulanic acid
Sulbactam
Tazobactam
What do cell wall synthesis inhibitors do?
Kill bacteria (bactericidal) that are dividing and growing
What are the 3 classes of Penicillins?
- Natural penicillins (Penicillin G)
- Antistaphylococcal penicillins (Nafcillin)
- Extended spectrum penicillins (Ampicillin and the antipseudomonal penicillins)
What is the MOA of penicillins?
They inhibit the cross-linking step in the synthesis of bacterial cell walls. They inactivate a transpeptidase which is normally responsible for cross-linking the linear glycopeptide strands of bacterial cell walls. They are bactericidal causing cell lysis and death.
What type of organisms are needed in order for penicillins to work the best?
Rapidly growing organisms with a peptidoglycan cell wall.
-These organisms do NOT have these structures and therefore are inactive against these: Mycobacteria, fungi, protozoa, and viruses.
What are the 3 steps that are taken in the process of cell wall disruption by penicillins?
- Penicillins bind to enzymes involved in cell wall synthesis called Penicillin binding proteins (PBPs).
- Some PBPs are transpeptidases which help in the cross-linking of cell wall chains. When the penicillin binds to the transpeptidase it causes blocking of the cross-linking.
- Gram-positive cocci also produce degradative enzymes called autolysins that help in the remodeling of the cell wall if something goes wrong. Penicillins have also been found to bind to these autolysins, causing self-destruction.
Gram __(+/-)__ bacterial cell walls are easily transversed by penicillins.
Gram+
Why don’t penicillins affect gram negative bacteria?
Gram negative bacteria have an extra outer wall known as the LPS. This LPS layer blocks the penicillin from entering on its own. The lipid filled channels (porins) on the outer membrane are needed in order for penicillin to enter. This is why penicillins differ in their capability for entry between gram+ and gram- bacteria.
What are the natural penicillins?
Penicillin G and Penicillin V
What type of infections is penicillin G used for?
Treponemal and clostridium infections
What bacteria is penicillin G good to treat against (more general groups not specific names per say)?
Gram + cocci and gram+ bacilli, Gram- cocci and spirochetes. Also, many oral anaerobes are susceptible
T/F - Penicillin G is NOT susceptible to beta lactamases.
FALSE - Penicillin G IS susceptible to beta lactamases. They are also unstable at acidic pH and gastric environment inactivates it.
What is the drug of choice for gas gangrene usually due to Clostridium perfringens?
Penicillin G (in combination with Clindamycin)
What drug is used in diphtheria for acute and chronic carrier states?
Penicillin G
It is also used in anthrax, actinomycosis, and listeria infections.
What drug is highly active against Treponema palladium (syphilis) with no resistance?
Penicillin
If a patient was to have syphilis and was penicillin allergic, what would be the drug of choice (hint: more than one drug)?
Benzathine penicillin and doxycycline