Exam 5 Flashcards
What is antibiotic selection?
The survival of an antibiotic resistant population of cells within a large population of antibiotic sensitive cells
AKA Survival of the Fittest
Where can ABX selection occur?
Practically anywhere that bacteria and abx is present
A common use for abx selection in microbiological research.
When identifying a particular cell that contains the DNA of interest (e.g. plasma) you can isolate the one you care about.
Why does every plasmid used for scientific research contain an abx resistance marker?
so you can identify the cells that got the plasma
Imagine you have a sample of bacteria that is a mixture of ampicillin resistant cells & ampicillin sensitive cells. How could you isolate the resistant ones?
Plate them of a medium with ampicillin. The ones that grow or produce colonies are resistant
What antibiotic class do cells containing BLA marker become resistant to?
ampicillin (any penicillins)
What antibiotic class do cells containing AAC marker become resistant to?
Kanamycin (aminoglycosides)
What antibiotic class do cells containing CAT marker become resistant to?
chloramphenicol acetyl transferase
a typical inducer of tet ON/OFF
doxycycline (dox)
tet ON with TET
turns gene expression ON
Makes repressor leave the operator
tet ON without TET
repressor binds to the operator no transcription
tet OFF with TET
turns gene expression OFF
Makes TA & repressor leave the operator
tet OFF without TET
TA binds to repressor, allows transcription
Typical way to administer TET or DOX to an animal
add to drinking water
contrast regulation of ABX in countries
U.S.= Dr. prescribed, prescription, pharmacy Other= over the counter
Over the counter
Pro: cheaper
Con: could experience antibiotic resistance
Prescription
Pro: Correct course, take correct drug
Con: expensive
Most prevalent use of ABX worldwide
agriculture
Effects do ABX have when added to animal food?
- Increased growth promotion (gp)
2. reduced risk of diseases
What is meant by gp
- faster time to increase weight for the market
- use less to get more
- more protein to fat in meat
How did advent of ABX help modern industrial production?
It allowed for less risk of spreading infection, allowing higher density of animals in cities
Name a class abx not used in animals
chloramphenicol (detect residue) or Oxazolidone
Why is monesin considered safe abx in cattle/dairy?
there is no document of ABX resistance to it. its also not a clinical ABX
Mechanism of action of monesin
ionfore: typically a sodium pump crosses the cell membrane, which causes bacteria to not grow
What is the accepted mechanism for ABX permit gp
it surpasses gut microbes, they take the energy from food. so if you eliminate them, it allows more energy into the animal which can reduce inflammation
What evidence led scientist to believe gp abx affected gut bacteria rather than physiology of animal?
- use of an ABX that doesn’t enter the blood stream still works for growth promotion, the ABX is just limited to the gut
- use germ free animals- give them ABX and there is no growth promotion( have to have microbiota to see growth effects)
ABX GP downside?
risk of increased abx resistance because abx selection is happening
Actual develop/modify in resistance zoonotic organisms harming human health is extremely difficult to document/quantify. Why gov. take action to limit abx in animal production?
- rather be safe than sorry. lower the chance of ABX resistance. be proactive even if no evidence
- even if had to document/ ABX selection has to be happening
Under U.S. VFD 2 conditions abx is given to animals
To treat disease
To prevent disease