Antibiotics resistance and misuse Flashcards
What are antibiotics?
Chemicals used to kill bacteria
Produced by bacteria or fungi
Not bacterisins
In low concentration used by bacteria in communication
What role does Darwins theory of evolution play in resistance?
Most pragmatic example of survival of the fittest
As use of antibiotics increases, so does resistance as stonger selection pressure exerted
Process of resistance
- Accumulation of resistant bacteria
- Mutant selection
- Spread of resistance via HGT
- Spread of resistant strains
What two types of selection pressures act on bacterial population?
Those that act on DNA level
Those that act on how the bacteria is spread
Examples of selection pressures that act on a DNA scale
Antibiotic use
Environmental antibiotic exposure
Exposure to heavy metals
Other factors like age and class
Examples of selection pressure that act on how bacteria is spread
Crowding
Travel
Poor hygiene
Animals
Mechanisms of resistance that bacteria use
- Efflux pump
- Antibiotic degradation and alteration
- Change gene expression of target proteins
How does the bacteria cause antibiotic degradation or alteration?
Gene produces protein that detoxifies the antibiotic via cleaving or conjugating
How does the efflux pump make the bacteria resitant?
Protein is encoded by gene that inserts itself into the membrane
This protein exports antibiotics from the inside of the cell to the outside
Decreases the intracellular concentration of the antibiotic
What are the two types of resistance the bacteria can acquire?
Intrinsic
Acquired
What is intrinsic resistance?
Naturally occuring trait of an organism
Species or genus specific
Examples of intrinsic resistance
Impermeable to the antibiotic
No receptor for the antibiotic to bind
How does changing the gene expression of targeted proteins confer resistance?
As antibodies only target one specific protein, changing its expression will render the antibiotic useless
The protein may change shape
The protein may be overproduced so the antibiotic becomes oversaturated
What are amalgam restorations
Fillings put on your teeth
Made of copper, tin, silver and mercury
Do bacteria gain resistance to amalgam restorations?
Yes, via genes on mobile genetic elements to other resistances
How are the resistance genes transferred between bacteria?
- Transformation
- Transduction
- Conjugation
What does transformation entail?
Transfer of free DNA from dead host and living recipient
when bacterial cells die and lyse, they release their contents into the environment
Their DNA is taken up by competent cells
DNA is incorporated into their genome and resistance will be expressed
What does conjugation entail?
Between live donor and recipient
ATP dependent mechanism whereby there is a tranfer of plasmid or conjugative transposon containing the resistance gene
What is a conjugative transposon?
Transposons are small pieces of DNA that insert themselves into another locus on a genome
What does transduction entail?
Uses bacteriophages
VIral delivery system whereby phages invade bacteria and cause them to lyse.
During their replication, phages have inserted genome from the bacteria into phage particles
When the bacteria lyse and release these phages, they are now free to invade other cells and integrates the genome containing the resistant gene into the new hosts
What are nanotubes?
Way in which bacteria become interconnected and transmit information through channels built between them
Pilli-like structures
Speculations
What is the feature of developing a solution for antibiotic resistance?
Bury bacteria in soil to look for natural antibiotics
Stewardship
How was Teixobactin discovered?
Bury bacteria underground to see if there are natural antibodies in the soil that can combat them
Teixobactin is a soil antibiotic against gram positive bacteria
What is Stewardship?
Doctors have to be careful when prescribing pills
40% of GPs admit to feeling pressured to prescribe antibiotics
30% admit to falling under pressure and giving antibiotics
How is antibiotic use in the present day?
By 200 days of life, 70% of infants have been subjected to antibiotics
By age 8, 97% of children have been subjected to antibiotics
