Pharm: L25: Penicillins Flashcards
*Know the MOA, (What she covers in lecture is what we need to know). *MOA for all of them. Route of Administration, Adverse Effects, (Broad spectrum, etc) *If she says something more than a couple of times, then KNOW IT!
1
Q
Inhibitors of Cell Wall Synthesis
- What structure gives the bacterial cell wall rigidity and resistance to osmotic lysis in G+ and G- bacteria?
a. What are the major proteins involved in the synthesis of this cell wall structure?
b. What targets these major proteins?
c. What is this structure made of?
A
- PEPTIDOGLYCAN
a. Penicillin Binding Proteins (PBPs)
b. B-Lactam Antibiotics
c. Backbone of NAD and NAM (sugars that alternate); They have a chain of 4 AAs that extend down the backbones and a PEPTIDE Bride forms b/w them (cross-links the Peptide Chains)
2
Q
Cell Wall/Peptidoglycan
- Major difference b/w Bacterial and Mammalian cells is the presence in bacteria of what?
- The Cell Wall protects bacterial cells from what?
- In G+, Peptidoglycan is what?
- What about G- ?
A
- Rigid Cell Wall External to the cell membrane
- Osmotic Rupture
- it’s the ONLY layered structure External to the Cell Membrane and is THICK (20-80 nm)
- There’s an outer membrane external to a thin Peptidoglycan Layer (1 nm)
3
Q
Peptidoglycan formation
- Inhibition of any stage of the SYNTHESIS, Export, or assembly of the Peptidoglycan lead to what?
- How is Peptidoglycan formed?
- Where do B-LACTAMS act?
A
- Inhibition of Bacterial Cell Growth, and usually in CELL DEATH!
- Add Subunits (sugar w/5 AAs) that are made in the Cytoplasm. Transport thru cytoplasmic membrane to the cell surface, and Cross-linking occurs that cleaves the Terminal Stem-peptide AA.
- On the Peptidoglycan cell wall!
4
Q
Peptidoglycan Synthesis
- Transglycosylation
a. Formed by what Proteins? - Transpeptidation
a. Formed by what proteins? - Where does B-Lactams affect this process?
A
- Joining NAM-NAG
a. PBPs - Cross Links Pentapeptides
a. PBPs - They Bind to the PBPs
5
Q
- What do Glycopeptides do?
a. What is the name of one of them? - What do B-Lactam Antibiotics do?
a. Name the B-Lactam classes (4)
b. What inactivates them?
A
- Steric Inhibition of adding subunits to the Peptidoglycan Backbone
a. VANCOMYCIN - Prevent Cross-Linking (TRANSPEPTIDATION)
a. Penicillins, Cephalosporins, Carbapenems, and Monobactams
b. Penicillinases and B-Lactamases (Hydrolyze B-Lactam ring thus inactivating the antibiotic)
6
Q
Lysis and Autolysins (*Know this stuff…she talked about this quite a bit)
- What is the MOST IMPORTANT thing to know about killing bacterium with B-Lactams? (what state do they have to be in)
- Which antibiotics that inhibit bacterial cell-wall synthesis are Bactericidal?
- What is the main cause of Lysis of the Bacterium?
a. How does this happen? - What PREVENTS the action of Cell Wall Synthesis Inhibitors?
a. What drug?
A
- Have to be in a STATE of GROWTH (if they are STATIC, then they will not work!!)
- Basically ALL OF THEM (cuz they lead to Osmotic Lysis)
- Lose cell-wall integrity due to their own Remodeling Enzymes (AUTOLYSINS): They cleave the Peptidoglycan bonds during normal cell growth.
a. When the antibiotics inhibit cell wall growth, AUTOLYSIS still occurs, leading to cell wall weakness and eventual lysis. - Protein Synthesis Inhibitors
a. Chloramphenicol
7
Q
What is difficult to treat?
A
- Pseudomonas Aeruginosa!
* Learn these by Groups…
* Bactericidal
8
Q
Inhibitors of Cell Wall Synthesis
- Agents that Affect the Cell wall? (2)
A
- B-Lactam Antibiotics and Other Antibiotics (Bacitracin, Vancomycin, and Daptomycin)
9
Q
Inhibitors of Cell Wall Synthesis
- B-Lactam Antibiotics do what?
A
- Inhibit Cell Wall Synthesis, thus they are BACTERICIDAL!!
Penicillins, Cephalosporins, Carbapenems, and Monobactams
10
Q
- What are the 4 B-Lactam Groups?
a. Why are they called B-Lactams? - What 4 are Not B-Lactams?
A
- Penicillins, Cephalosporins, Monobactams, and Carbapenems
a. They all have a B-Lactam Ring - Vancomycin, Phosphomycin, Bacitracin, and Cycloserine
11
Q
Penicillins
- Natural Penicillins (4)
- Penicillinase Resistant (3): NOM
- Extended Spectrum (AA)
- Antispeudomonal (PTC)
A
- PENICILLIN G; Pen V, Procain Pen G, Benzathine Pen
- NAFCILLIN, Oxacillin, and Methicillin
- AMPICILLIN, Amoxicillin
- PIPERACILLIN, Ticarcillin, Carbenicillin
12
Q
Penicillins: Chemistry
- What is the main structural requirement for their activity?
- Antibacterial Activity of Penicillin RESIDES in what?
a. What happens if this is destroyed?
b. What destroys it?
A
- Its nucleus
- in the INTACT B-LACTAM RING
a. Loss of ANTIBACTERIAL ACTION
b. B-LACATAMASE (PENICILLINASE)
13
Q
Natural Penicillins
- What are they again? (Name the 4)
- What is the BIG thing to remember about this group (Have the HIGHEST what?)
a. Not so good for what bacteria?
b. What is the trend to remember? - INACTIVATED BY what?
- ANTIPSEUDOMONAL Activity?
- How does the body get rid of them?
a. What can be TAKEN with them to help decrease elimination rates? - CNS penestration?
A
- Pen G, Pen V, Benzathine Pen, and Procaine Pen G
- HIGHEST antibacterial activity against G+ BACTERIA!! (even G+ Anaerobic Bacteria)
a. not so good for SOME G- Bacteria
b. As you go down the list of PENICILLINS that she listed, know that Natural Penicillins Have the HIGHEST G + activity, and lowest G- activity, and G+ activity decreases as G- activity Increases moving to the next groups. - PENICILLINASE (B-LACTAMASE)
- NONE!
- Active Transport in the Kidney
a. Probenicid - POOR
14
Q
Mechanism of Action of Penicillins
- Type of Antibiotics?
- What stage of Cell Wall Synthesis do they INHIBIT?
- When are they ONLY BACTERICIDAL?
A
- BACTERICIDAL
- FINAL STAGE (Cross-linking: Transpeptidation). Bind to PBPs. (PBPs catalyze the RxN that removes the Terminal Alanine to form a crosslink w/the nearby peptide)
- ONLY when bacteria are ACTIVELY GROWING and Synthesizing CELL WALLS
15
Q
Natural Penicillins: Route of Administration
- Pen G?
- Pen V
- Benzathine Pen
- Pro Pen G
A
- (IV, IM)
- Orally useful (tends to be Acid resistant)
- IM
- IM
* Works well agains Streptococcus Pneumoniae (but resistance to Pen G has occurred and is increasing); Good against SYPHILIS.