Anti-microbials Flashcards
How do we classify antimicrobials?
By pathogen eg antibacterial, antifungal, antiviral or antiprotzoal
What are the types of resistance
Intrinsic- No target or access for the drug which is generally permanent.
Acquired- New mutations or genetic material acquired which is then permanent.
Adaptive- Organism adapts to stress and this is reversible.
What are the genetics of resistance
Chromosomal gene mutation
Horizontal gene transfer
How do we classify antibacterials?
Bacteriocidal or bacterio static Spectrum broad or narrow Target site (mechanism of action) Chemical structure
What makes an ideal antimicrobial?
Selective toxicity Few adverse effects Reaches the site of infection Oral and IV available Long Half life (better compliance) No interference with other meds
List different antibiotic mechanisms:
Cell wall synthesis
Cell membrane function
Protein synthesis
Nucleic acid synthesis
Name tow sub categories of cell wall synthesis targeting antibiotics.
Beta Lactams
Glycopeptides
What type of antibiotic are tetracycline?
protein synthesis targeting.
Give an example of nucleic acid synthesis targeting antibiotic.
Trimethoprim
How do penicillin and vancomycin differ?
They both effect cell wall synthesis.
Penecillin binds penecillin binding protein that normally crosslinks peptidoglycan chains.
Vancomycin blocks the penicillin binding proteins from binding.
How do fluoroquinolone work?
Bind enzymes and block DNA replication.
EG ciprofloxacin and trimethoprim.
Outline mechanisms of resistance:
Drug inactivating enzymes (Beta lactamases, amino glycoside enzymes) Altered Target (lowering the affinity of the target enzyme) Altered uptake (decreased permeability or increased flux)
How do fluoroquinolone work?
Bind enzymes, inhibit DNA gyrase and block DNA replication. Active giants Gram -ve, but risk C diff
EG ciprofloxacin and trimethoprim.
Describe disc sensitivity testing.
Culture a bacteria and apply filter paper discs that are impregnated with antimicrobials. Look at radial illimination to ascertain which one its most sensitive to.
What is minimum inhibitory concentration?
Used to get a quantitive value of dose needed for adequate response. Solution of bacteria spread into different test tubes with different concentrations of antibiotic- check what the west dose to eliminate the bacteria is.
