Drugs - Worksession Flashcards
How does Rifampicin work?
interacts with bacterial RNA polymerase (binds to beta subunit)
prevents phosphodiester bond formation
no transcription = no protein
cell death occurs due to lack of protein synthesis
How might resistance to Rifampicin?
mutation of beta subunit of RNA polymerase
some bacterial polymerases will be affected more than others
there may be mutations in the rpoB gene
What is conjugation?
A pillus can form between 2 bacteria and information can be transferred between genomes. This can pass on resistance to certain antibiotics.
What is Tetracycline?
An antibiotic that prevents protein synthesis in bacteria.
How does Tetracycline work?
binds to 30S subunit of bacterial ribosome
stops translation
tRNA cannot bind to ribosome therefore no protein synthesis
Which common problem is Tetracycline used to treat?
Acne
How is Tetracycline specific to bacteria?
Only binds to the 30S subunit of the 70S bacterial ribosomes. It cannot bind to the subunits of human 80S ribosomes.
How might bacteria have resistance to tetracycline?
they can pump it out efficiently via eflux pump
they may have an enzyme that can add acetyl groups to tetracycline to prevent it from working
Which drug stops cells from dividing rapidly?
Methotrexate
How does methotrexate work?
blocks the action and metabolism of folic acid
stops the synthesis of purines therefore stops DNA synthesis
by stopping the enzyme DHFR
What is folic acid?
A cofactor in amino acid/protein synthesis
How might bacteria be resistant to methotrexate?
they may have decreased uptake and retention of MTX
they may have a mutated form of DHFR so MTX doesn’t bind as well
increased lysosomal hydrolase that hydrolyses MTX
What are some of the side effects of MTX?
hair loss, nausea and immune resistance decreases
What is MTX used as a treatment for?
bacterial infections, cancer and autoimmune diseases
What is Rifampicin?
An antibiotic that inhibits bacterial transcription.
