Antibiotics And Antimicrobials Flashcards
Outline a classification of antimicrobials (4)
- bactericida (kills) or bacteriostatic (inhibits)
- spectrum> broad vs narrow
- target site (mechanism of action)
- chemical structure of antibiotic
every class of Antibacterials have their own mechanism of actions,
Describe the mechanism of action of the main groups of antimicrobials and guv eexamples.
Describe the principles of antimicrobial resistance and its impact on antimicrobial prescribing.
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Describe the concept of antimicrobial stewardship
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Outline measures to take to ensure the appropriate use of antimicrobials
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what is an antimicrobial?
an agent that is active against small microbes, either protozoa, antifungal, anti viral,
what is an antibiotic?
an agent derived from another living creature.
ex: penicillin is developed from the mould penicillium.
what r the ideal features of antimicrobial agents?
- selective toxicity (we want it to be more toxic to the microbe than the host)
- few side effects
- reach infection site (ex: meningitis, we want it to get to csf.)
- oral/IV
- longer half life
- doesn’t interfere with other drugs -
EVERY drug has some kind of degree of toxicity on the HOST cell too lil 2asaf ;(
so we try to find a drug that would to be more toxic to the microbe than the host
where do we want to target the drug when treating meningitis?
CSF
types of resistance
- intrinsic: if the bacterium has no target for the drug, or the drug can’t get into the bacterium.
- acquired the microbe changes genetically either by mutation or acquires a new genetic material (look at ur notes alaa)
- adaptive
what is trimethoprim? describe its mechanism of action
“Try me”😎
treatment of UTI, it interferes w/ folic acid synthesis, which is responsible in NUCLEIC ACID synthesis.
**A potent inhibitor of bacterial dihydrofolate reductase. Leading to a decreased availability of the tetrahydrofolate cofactors required for purine, pyrimidine, and amino acid synthesis
describe the cell wall synthesis in bacteria
NAM and NAG from the peptidoglycan layer peptidoglycans r cross linked together via PBP (transpeptidase)
Mechanism of action of Flouroquiolones
it interferes with nucleic acid synthesis.
works by inhibiting 2 of the enzymes involved in dna replication,
-DNA Gyrase -Topoimerase that r involved with supercoiling
what r the 3 mechanisms of bacterial resistance?
-Enzymes bacteria can make enzymes that can inhibit the drug! ex: B lactamases will inactive the B lactam ring in the drug (ur notes alaa) - Altered target Ex: MR SA a bacteria which is resistance to Metacillin. -Altered uptake 1) LOW permeability>> drug can’t get inside the organ 2) EFFLUX pump>>drug can get in, BUTT an efflux pump developed to push the drug out!
describe the genetic basis of antibiotic resistance
1) chromosomal gene mutation During bacterial division, by chance, there has been a mutation, and the plasmid carries a ‘RESISTANT GENE” in the presence of an antibiotic, all the susepitble ones r killed, but the one that had the mutation survived IT BECOME THE DOMINANT STRAIN! and that organism is now resistance. it has been selected by the us of antibiotics. 2) Horizontal gene transfer -conjugation (sex pili) -transduction (injected in bacteria via bacteriophage) -transformation
what is a spore?
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how can u measure antibiotic activity?
via disk sensitivity testing. -grow the organism on an agar plate -put a little paper filtered disk that has antibiotic. -antiobiotic diffuses into the agar **if antibiotic is effective, it won’t grow in that area (clear space)
which group does Flucloxacillin fall into? what is it active against?
Penicillin **staph and Strep cocci
which group does ceftriaxone fall into? give example of when we administer it
Cephalosporins, Sepsis