Antibiotic resistance
Antibiotics recap
Bacteriostatic: growth inhibition e.g., protein synthesis inhibitors such as tetracycline.
Bactericidal: cell killing e.g., beta lactams.
We target:
o Cell wall synthesis
o Protein synthesis
o Nucleic aid synthesis
o Metabolic pathways
General causes of resistance to antibiotics
Natural: become resistant without even having come into contact with the antibiotic
Sensitive bacteria develop resistance:
o Modification of the target
o Enzyme inactivation for the antibiotic
o Organism pumps out the antibiotic (efflux)
What is antibiotic resistance?
The acquired ability of a microorganism to resist the effects of a chemotherapeutic
agent which it is normally sensitive to.
Does not include naturally resistant bacteria.
Why does antibiotic resistance develop?
Mutation:
in their DNA which can confer resistance.
by altering the bacterial target.
This mutation can cause:
o Alter the target for the drug: so it can no longer bind.
o A metabolic bypass: the drug binds and is metabolised before it can have an
effect.
o The decreased influx and increased efflux of antibiotics.
o Drug modification: e.g., can develop beta-lactamases which degrade the drug
before it gets to the cell.
o Drug destruction.
Antibiotics recap
Bacteriostatic: growth inhibition e.g., protein synthesis inhibitors such as tetracycline.
Bactericidal: cell killing e.g., beta lactams.
We target:
o Cell wall synthesis
o Protein synthesis
o Nucleic aid synthesis
o Metabolic pathways
General causes of resistance to antibiotics
Natural: become resistant without even having come into contact with the antibiotic
Sensitive bacteria develop resistance:
o Modification of the target
o Enzyme inactivation for the antibiotic
o Organism pumps out the antibiotic (efflux)
What is antibiotic resistance?
The acquired ability of a microorganism to resist the effects of a chemotherapeutic
agent which it is normally sensitive to.
Does not include naturally resistant bacteria.
Why does antibiotic resistance develop?
Mutation:
in their DNA which can confer resistance.
by altering the bacterial target.
This mutation can cause:
o Alter the target for the drug: so it can no longer bind.
o A metabolic bypass: the drug binds and is metabolised before it can have an
effect.
o The decreased influx and increased efflux of antibiotics.
o Drug modification: e.g., can develop beta-lactamases which degrade the drug
before it gets to the cell.
o Drug destruction.
