Antibiotic Resistance Flashcards
Examples of natural resistance:
Target not present (e.g. no cell wall)
Target not accessible (antibiotic can’t get in)
Developmental structure/state
What is a biofilm?
Organisms behaving as a multi-cellular community
More resistant to anti microbial agents and host defences
What is a persistor cell?
A metabolically inert cell - very slow growth, dormant or non-living
Unaffected by antibiotics
Increase in community
Spatial heterogeneity:
Range of different species each with their own function and properties
How do bacteria become resistant to an antibiotic?
Result of a change in bacterial DNA
Bacteriophage definition:
Viruses that effect bacteria
Bacterial transformation:
When bacteria die and the cells break apart, ‘free-floating’ DNA released into surrounding environment may be ‘scavenged’ by other bacteria and incorporated into DNA - the DNA may contain genes for antibiotic resistance
Bacterial conjugation:
Replication and transfer of plasmid DNA - plasmid DNA may contain genes for resistance
Bacterial transduction:
Bacterial DNA transferred from one bacterium to the other inside a bacteriophage
Altered binding site resistance:
A change in bacterial DNA can cause a change in the gene product which is the target of the antibiotic
Resistance: Destruction of antibiotic
Bacteria may possess genes which code for enzymes that chemically degrade or inactivate the antibiotic
How do β -lactamases destroy antibiotics?
β -lactamases and cephalosporinases target and disrupt the β-lactam ring of the antibiotics
Example of enzymes that destroys antibiotics:
ESBLs:
- Inactive almost all penicillins and
cephalosporins
- Produced by some Gram-negative bacteria
Resistance: Increased efflux
Pumps actively, exports antibiotics out of the bacterial cell
Genetic change may increase the rate of efflux - antibiotic pumped back out of the cell before it has time to act
Function of β -lactamases inhibitors:
Stop the degradation of β-lactam antibiotics
