ANTIBACTERIAL DRUGS Flashcards
what are antimicrobials?
any natural or synthetic chemicals that kill or inhibit the growth of microorganisms
what are bactericidals?
antibiotics that kill bacteria
what does bacteriostatic mean?
Capable of inhibiting the growth or reproduction of bacteria.
what is the ‘selective toxicity of antimicrobials’?
they must be highly effective against the microbe but have minimal or no toxicity to humans.
what are the ideal properties of antimicrobials?
- have selective toxicity
- be bactericidal
- have slow emergence of resistance
- narrow spectrum of activity (be specific to a microbe)
what are the benefits of narrow-spectrum antibiotics?
they only kill the microbe not wanted, minimizing collateral damage on the microbiota and reduces the chance of resistance
what do antibiotics target?
- cell wall synthesis
- enzymes involved in metabolism
- protein synthesis
- nucleic acid synthesis
- cytoplasmic membrane function
how do beta lactams kill bacteria?
Act by inhibiting the synthesis of the peptidoglycan layer of bacterial cell walls by inhibiting the enzyme required for transpeptidation
how do glycopeptides kill bacteria?
inhibit cell wall synthesis by blocking new linkages of cell wall subunits
how do sulfonamides work?
they competitively iinhibit bacterial enzyme DPS in the folic acid synthesis pathway, blocking nucleic acid synthesis
describe the structure of eukaryotes ribosomes?
they have 40S and a 60S subunit
describe the structure of prokaryotes ribosomes?
they have 30S and 50S subunitys
how do aminoglycosides work?
they inhibit bacterial protein synthesis by binding to the 30S subunit
how do tetracyclines work?
they inhibit bacterial protein synthesis by binding to the 30S subunit
how do macrolides work?
they inhibit bacterial protein synthesis by binding to the 50S subunit
what are the 4 ways antibiotics can inhibit bacterial protein synthesis?
- inhibiting the 30S subunit
- inhibiting the 50S subunit
- inhibiting tRNA
- inhibiting EF-G elongation factor which is required for elongation of peptide synthesis
what can inhibit EF-G elongation factor?
fusidic acid
how do quinolones work?
They bind to the topoisomerase IV/DNA gyrase–DNA complexes and this results in the inhibition of DNA replication.
how do rifamycins work?
they block mRNA synthesis
how do polymyxins work?
they act like a detergent to inhibit cytoplasmic membrane functuon
why are polymyxins rarely used?
they are toxic and have severe side effects
what are some examples of broad spectrum antibiotics?
older penicillins
macrolides
vancomycin
what are some examples of narrow spectrum antibiotics?
aminoglycosides
2nd and 3rd generation cephalosporins
quinolones
some synthetic penicillins
what has antibiotic resistance risen?
misuse and overuse of antibiotics
not finishing the whole course of antibiotics
poor infection prevention
outline the mechanism of antibiotic resistance?
a mutation occurs causing resistance
use of antibiotic provides a selection pressure
more reistsant bacteria survive and reproduce to pass on their resistance allele by vertical and horizontal gene transmission
frequency of resistance allele increases in population
how can we prevent antibiotic resistance?
only using antibiotics when correctly prescribed and completing the full course
never sharing antibiotics or using left over prescriptions
regularly washing hands
preparing food hygeinically
avoiding close contact with sick people
practicing safer sex
getting vaccinated
