Antibiotic Targets Flashcards
Where does Penicillin Act?
Acts on Penicillin Binding Enzymes that promote the synthesis of the pepdidogylcan wall. Bacteria constantly recycle this wall and as a consequence will be killed when they are unable to recycle
Where does vacomycin act
Acts by binding to the D-Ala-D-Ala petide link in the synthesis of the peptdoglycan wall. Reistance can emerge with enterococci which tey swap the last alanine for a D-Lac. VISA can arise yet not the same mechanisms
Where do the Aminoglycosides act?
Thy act on the 30S ribosome to impair accurate mRNA reading. Includes tobramycin, gentamycin, streptomycin and kanamycin. Mostly act in GNs
Where do Tetracylines act?
Include Doxycyline and tetracycline and works by a similar mechanism as aminoglycosides
Where do Macrolides act?
Translocation of peptide chain
Where do chromamphenicols act
Peptidyl transfer
Where does Amphotericin act
on ergosterol
where does trimethoprim act?
On folic acid synthesis
What are some mechanisms of Drug structure modification by bacteria
- Hydroolysis eg Beta lactams
- Covalent modification eg aminoglycosides and chloramphenocol
What are some mechanisms of Drug inactivation by bacteria by modifying the target in which antibiotics act
○ Modifiy the target to a less sensitive form eg B-lactam and vancomycin
○ Over-produce product eg vancomycin in VISA
What are some mechanisms of Drug inactivation by bacteria by modifying drug acess to drug target
○ Reduced entry into cell eg aminoglycosides
○ Increased efflux from cell eg aminoglycosides and tetracycline
What are some mechanisms of Drug inactivation by bacteria to prevent activation of prodrugs
○ Metronidazole and isoniazid
How does cluvanic acid work?
Is a Beta lactamase inhibitor
What is the specrtum of Amoxycillin/Ampicillin
Includes gram negative bacteria
Which drugs act to inhibit nucleic acid synthesis
- Quinolones, rafamycin and sulfonamides, trimethoprim
What three drugs are given as prodrugs
Metronidazole, isonazid and 5-flurocytosine
Example were two antibiotics act in synergy via - Inhibition of enzyme that degrades another antibiotic
○ Penicillin G + streptomycin in meningitis or Ampicillin and cluvanic acid in many Penicillin resistant organisms
Example were two antibiotics act in synergy via - - Blocking the DNA proudcution pathway yet at different steps
Sulphonymides and trimethoprim (DNA inhibition cotrimoxazole)
What is the mechanisms by which cephlosporins act
They act by inhibiting the PBP at the cell wall and inhibit peptidoglycan synthesis of the cell wall, they have wide spread action on many different bacteria of GN and GP. They are mostly resistant to the action of Beta lactamases
Antibiotics that act in synergy with increasing uptake in bacteria and in fungi
Flucytosine + amphotericin in fungi
Gentamicin and penicillin in bacteria
Drugs that act in synergy in targeting prostate cancer
Cisplatin to break DNA strands and etoposide to inhibit topisomerases
