Lecture 5: Antibiotic Resistance + Genetic Transfer Flashcards
how do bacteria become genetically resistant?
spread of resistant genes through genetic transfer acts
what is competence?
free DNA is taken up by the cell from the environment and assimilated into genome
what are 2 ways cells can become competent?
naturally, and by exposure
what is conjugation?
transfer of genes from one prokaryotic cell to another through direct contact
conjugation is very ___ and __
fast and efficient
Lederberg & Tatum discovered ___ in 1946
bacteria share DNA
how did Lederberg and Tatum show that bacteria share DNA?
two separate broths in minimum media would not grow colonies, byt when mixed together, they were able to form colonies
how was it proved that cells need to touch to share DNA by conjugation?
U-tube with filter that wouldnt let bacteria through: no sharing even if DNA could get through
genes can be transferred laterally through ___
viruses
how does lateral transfer of DNA work?
viruses package DNA from one cell and insert it into another
a bacteriophage inserts __ into a bacteria and begins
its own phage DNA; replicating itself and using the resources of the bacterial cell
phages will package new phages and sometimes accidentally incorporate ___ into them
bacterial DNA
an infected bacterial strain can make its own __
tryptophan
what is transduction?
transfer of DNA by bacteriophage
mutation in ribosome genes results in ___ not being effective
protein synthesis inhibitors
mutations in DNA gyrase prevents __ from working, meaning ___ will happen slower
fluoroquinolones; unwinding and replication of DNA
what is MRSA
methicilin resistant stapphylococcus aureus
MRSA is methicilin resistant because__
resistant cassettes in genome caused by competence/conjugation
what is combination therapy?
treatment with multiple antibiotics to reduce occurrence of near lethal exposure
why is combination therapy more likely to work than a single antibiotic?
it is less likely to have 2 independent mutations in the same host in a short time. If one mutation happens, the second AB should maintain efficacy
before a combination therapy is given, what must happen first?
patient lab isolates to test that the combination and sensitivity will work
why is vancomycin resistant entercocci so dangerous?
just throwing their DNA around, naturally competent with many conjugative plasmids. Hard to clear infection and often results in death
what are the dangers of MTB (XDR) in terms of spreading?
latent phase = carriers unaware, airborne
what new drug was developed by Jansen Pharma?
Bedaquiline (TMC 207)
what is the mechanism of Bedaquiline?
targets ATP synthase in MTB bacteria
what are resistance cassettes?
packages of genes that cause resistance by competence / conjugation
why has the market for drugs shifted more towards lifestyle drugs?
because we cant keep up with pathogens, they evolve to the anti-biotic before is can be mass produced. Lifestyle also have return customers
