Antibiotics and Anti-fungals Flashcards
Important step in production of bacterial DNA synthesis
Production of tetrahydofolate
Important first step in production of THF
Paraaminobenzoate-> dihydropteroate
Enzyme for conversion of PABA to DHOp
DHOp synthase
Intermediate between DHOp and THF
Dihydrofolate
Enzyme in conversion of DHF to THF
DHF reductase
Important enzyme in bacterial DNA replication
DNA gyrase ( like our topoisomerase as releases tension)
Enzyme in bacterial synthesis
RNA polymerase- is different to ours but still does same job of producing RNA from DNA template
How is bacterial ribosome different to ours
Smaller
5 antibiotic classes for intracellular mechanisms
Sulphonamides Trimethoprim Fluoroquinolones Rifamycins Macrolides
MOA of sulphonamides
Targets DHOp synthase
MOA of trimethoprim
Targets DHF reductase
MOA of fluoroquinolones
Targets DNA gyrase
MOA of rifamycins
Targets bacterial RNA polymerase
MOA of macrolides
Inhibit bacterial ribosomes
Peptidoglycan synthesis
Pentapeptide added to NAM which associates with NAG to form PtG
How is PtG transported across membrane to form cell wall
bactoprenol
What forms links between PtG pentapeptides
Transpeptidases
5 drug classes targeting bacterial wall synthesis
Glycopeptides Bacitracin Beta-lactams Lipoproteins Polymyxins
MOA of glycopeptides
Binds to pentapeptides preventing PtG synthesis
MOA of bacitracin
Inhibits bactoprenol regeneration
MOA of beta lactams
Bind covalently to transpeptidases inhibiting PtG incorporation
MOA of lipopeptide
Disrupt Gram +ve cell walls
MOA of polymyxins
Bind to LPS and dsirupt gram -ve cell membranes
Causes of antibiotic resistance
Overprescription
Livestock farming
Lack of regulation in some areas in world
lack of development in antibiotic
5 methods of resistance
Production of destruction enzymes
Producing different target to drug that is resistant to action of drug
Altering the enzyme targeted by the drug which drug is ineffective to
Alterations in drug permeation to cell
Increase the amount of enzymes to decrease efficacy of the drug
Example of production of destruction enzymes
Beta-lactamase can hydrolyse the C-N bond of beta lactam ring
Can all penicillins fight against all bacteria
No there is variation amongst the classification in their efficacy against gram -ve and +ve
Example of producing different target to drug that is resistant to action of drug
Ecoli produce different DHF reductase that is resistant to trimethoprim
Example of altered enzyme
S aureus has mutation in ParC region of topoisomerase IV which is resistant to quinalones
Example of alterations in drug permeation
Reduction in aquaporins and increased efflux systems
What bacteria is alterations in drug permeations more relevant
Gram -ve
Example of hyperproduction of the target enzyme
E coli increase amount of DHF reductase making trimethoprin less effective
4 classifications of fungal infections
Superficial
Dermatophyte
Subcutaneous
Systemic
2 types of antifungals
Azoles
Polyenes
MOA of azoles
Inhibit P-450 dependent enzymes involved in membrane sterol synthesis
MOA of polyenes
Interact with cell membrane sterols forming membrane channels
