Intro to antimicrobial drugs Flashcards
principles antimicrobial chemotherapy
drugs should be toxic to invading microorganisks but not to the host
need to exploit biochemical differences between pathogen & host
gram positive bacteria easily treated by antibiotics
bacterial metabolism have 3 main stages of metabolism that we can target:
class 1 AND CLASS 2 AND CLASS 3
Class 1 reaction:
produce ATP & simple carbon compounds
class 2 reactions:
use energy & class 1 compounds to make small molecules
class 3 reactions
convert small molecules into macromolecules
antibiotics that target class 1 reactions: characteristics
similar to host reactions, multiple pathways to produce energy
-kill the host instead of the bacteria
antibiotics that target class 2 reactions: characteristics
folate biosynthetic pathway
antibiotics that target class 3 reactions: characteristics
particularly good target as differ between bacteria & host
antibiotics mostly target what class of reactions?
3
folate is essential for making?
DNA
folate to thymidylate for making DNA (process)
Foltate converted into dihydrofolate, which is reduced into tetrahydrofolate which is a cofactor to make thymidylate
why cant bacteriaget folate from their diet?
dont have any folate transporters, but they still need it
synthesis of folate is a very good target for antibiotics why?
because every bacteria needs to make folate.
If we hit synthesis with sulphonamide, that will hurt the bacteria but not the human
The enzyme, dihydrofolate reductase is structurally different in bacteria & in humans. therefore?
drug sensitivity to drug binding may be different
antibiotic trimethoprim
inhibits the bacterial form of the enzyme & not the human form
bacteria static
bacteria can’t make DNA, therefore they stop growing
broad spectrum antibiotic target
many different types of bacteria (gram positive &negative)
-but can cause antibiotic resistant bacteria
why are sulphonamides used very rarely?
have side effects that cause a lot of severe skin reactions
sulphonamides + trimethoprim can be used for a super folate inhibition in very severe infections such as:
pneumocytis (type of lung infection that you can get in HIV patients)
role of pepidoglycans:
Make up cell wall, which forms a ‘string bag’ around bacterial cells
Supports underlying plasma membrane
Together comprise the bacteria envelope
structure of peptidogylcan
- tetrapeptide side chains & peptide cross-links
- linking is catalysed by these enzymes called transpeptidase and carboxypeptidase
penicilin is a really good antibiotic against? (what bacteria?
gram-positive bacteria
class 3 reaction example
peptidodylcans & protein synthesis
cell wall provides?
mechanical strength that allows bacteria to survive environmental conditions that alter osmotic pressures
