Discussion Flashcards
(15 cards)
What is the mechanism/system used for stability in the plasmid?
The system is called for the plasmid addiction system. the mechanism kill plasmid free cells by to genes coding for a stable toxin and an antitoxin preventing the action of the toxin. when the cell no longer has the plasmid the antiode will break down to enzymes while the toxin is still stable and able to kill the cell ensuring that only plasmid bearing cells survive
For the ratios we had 1:1, 1:100 and 1:1000 what does this essentially mean?
wt:plasmid so we have less and less of the plasmid to see if the effect is concentration dependent
Why did we do the relative growth rate over again?
We did it over because of the big error bars and variation so we included more replicates
what can be an explanation for the MIC results?
It can be mutations, but we had two clones that were verified
Why did we do the cross-resistance?
to cover the basis
Why is there a debate about bactericidal and bacteriostatic
this is primarily based on in vitro measurements, such as MIC and MBC. But these may not consistently predict clinical outcomes as factors like drug concentration at the infection site, host immune response and the specific pathogen play significant roles
its not longer common to prescribe sxt and therefore not common to prescribe combination for uvi - but why?
In norway 20-25% of the e.coli isolates from urine resistant against trimethoprime-sulfamethoxazole. Thats why theres no need to prescribe the combination if the bacteria is resistant against one of the components. When there is UVIs you will often achieve treatment by just prescribing trimethoprime alone.
What happens with plasmids that are costly?
compensatory evolution can increase fitness and stability
whats the difference between fitness cost in plasmids vs in the chromosome?
Its more relevant in plasmids as they are extrachromosomal DNA which are more easily selected for than chromosomal change. A mutant needs to be selected against over generations because bacteria cant just lose a gene from its chromosome, while the plasmid strain can just drop the plasmid if its taking up too much energy and then replicate freely without it
why is plating assay limited?
is limited to how few colonies i get on each plate. with using fluorescently tagged strains and FACS, i could count thousand in a second and get more sensitive reults. on my project we decided to go old school du to time constrains and engineering clinical strains is much harder than lab strains. therefore we used selective/non-selective plating instead of tagged strains and FACS.
We conluded that there were no cross-resistance, but how do we know that and how would it look like if there were a cross-resistance?
The MIC would be higher than expected for more than one antibiotic in the same strain. if a strain is resistant to A due to a mechanism and that mechanism also affects antibiotic B, youd see increased MICs for both drugs.
If i could do this over how would i change or alter the opproach?
why does the relative growth rate look a bit weird for blembl?
Forgot to include the raw data in the appendix. had 3 biological and 3 technical replicates so in total 9 replicates, seen in the rawdata some outliers so by removing them the graph should look normal
What is so important about the MSC?
These are concentrations lower than the MIC so they dont inhibit growth but they can select for resistance. helps us explain how resistance grows even in the absence of anitbiotics and is relevant in wastewater, agriculture and gut microbiome.
