Antibiotics 1 Flashcards
What is the beta-lactams’ mode of action?
Inhibit cell wall formation
Form covalent bonds with proteins, inhibiting cross linking in the formation of the peptidoglycan cell wall (of bacteria)
What is the quinolones’ mode of action?
Inhibit DNA gyrase
DNA gyrase (topisomerase II) is responsible for negative supercoiling of bacterial DNA.
What is the glycopeptides mechanism of action?
Inhibit cell wall synthesis
By inhibiting release of cell wall components from the cell membrane, the peptidoglycan chain cannot form.
What is the mode of action of metronidazole?
Inhibit DNA replication
Anaerobic bacteria are able to react with metronidazole, resulting in the reduced form, which covalently binds to the DNA, inhibiting nucleic acid synthesis.
What is the mode of action of rifampicin?
Inhibition of RNA polymerase
Binds to bacterial RNA polymerase, but not mammalian
What is the mode of action of macrolides?
Inhibit protein synthesis
Bind to 50S subunit of ribosome, inhibiting translocation
What is the mode of action of trimethoprim?
Inhibits dihydrofolate reductase
An enzyme involved in metabolism of folate, important for DNA synthesis, repair etc.
Extremely high affinity for bacterial enzyme, not mammalian.
What is the mode of action of tetracyclines?
Prevent protein synthesis
Binds to 30s subunit of ribosome, inhibiting binding of tRNA to mRNA-ribosome complex
What is the mode of action of sulfonamides?
Inhibit dihydrofolate sythetase
An enzyme involved in metabolism of folate, important for DNA synthesis, repair etc.
What is the mode of action of aminoglycosides?
Inhibit protein synthesis
Bind to 30S subunit of ribosome, and cause misreading of the codon, making a toxic peptide.
What is the mode of action of chloramphenicol?
Inhibits protein synthesis
Binds to 50S subunit of ribosome, preventing binding of amino acids to tRNA
What are the classes of beta-lactams?
Penicillins
Carbapenems
Cephalosporins
Name 2 glycopeptides, and what they can be used to treat
Teicoplanin
Vancomycin
Staphylococci (severe infection; MRSA)
C. dificile
Name 2 penicillins, and what they can be used to treat
Flucloxacillin
Staphylococci
Amoxicillin/ampicillin - broad spectrum. Strep pneumoniae; H. influenza; H. pylori; Enterococci
Benzylpenicillin - meningococcal disease; syphilis; gram +ve
Fi
Carbapenems and cephalosporins are used to treat
Broad spectrum antibiotics, used to treat staph, strep, klebsiella, E.coli, pseudomonas spp.
NB Cephalosporins have varying sensitivities to some bacteria
