7 Antibacterial Resistance Flashcards
Define antibiotic resistance.
A situation where a type of bacterium (species or strain) is not susceptible to the active concentration of the antimicrobial agent
What are the two routes which bacterial resistance can result from?
Intrinsic properties and acquired characteristics
What does intrinsic resistance allow the bacterium to do? And what does this mean?
Function as normal which means the bacterium isn’t affected by the presence of the antibiotic
The bacterium can switch some genes on, what does this provide? Give an example.
Leads to synthesis of constituents which function to protect the cell which means the antibiotic cannot have full effect
An example is capsule formation
In what sort of bacteria is the intrinsic resistance protection method seen in and why?
Gram negative bacteria bue to complex cell wall (lipopolysaccharide (LPS) wall)
How does the lipopolysaccharide layer create antibiotic resistance?
LPS is hydrophobic which inhibits the entry of hydrophilic compounds - like antimicrobials
What does the LPS layer contain and what are they?
Porins- barrelled shaped proteins that act as channels (pores) to allow molecules to cross towards the cell
What sort of molecules do porins allow?
Small (up to 600 Daltons), hydrophilic molecules into the periplasm
Large molecules are unable to cross using this route
What does the lack of the LPS layer cause in Gram positive?
They do not have the same blockage of molecules which allows the passage through peptidoglycan of antimicrobials of up to 30 kDa
What does the secretion of exopolysaccharides do? And in what sort of bacteria?
Help to produce a biofilm which gives intrinsic resistance in both Gram positive and Gram negative
How does a biofilm matrix protect the cell?
Antimicrobials are generally unable to penetrate the biofilm matrix therefore antimicrobials do not reach the bacteria
What can some bacteria produce to degrade antimicrobials?
Enzymes
What does acquired resistance entail?
Bacterial cells altering their genetic material
What are the two routes of acquired resistance?
Mutations following antimicrobial exposure
Acquisition of new genes (HGT/LGT)
What is chromosomal mutation and what are the types that can occur?
Changes to the genetic material of the cells
Types that can occur are insertions, deletions, inversions and point substitutions
