Molecular Badis Antibiotic Resistance Flashcards
Greatest use of antibiotics?
Growth promotion in agriculture
What’s the biggest way bacteria become resistant?
By transfer of genetic info
Become resistant by mutation
What is the chance of a bacteria becoming resistant to 2 antibiotics?
(Adaptive)
10 power -8
What do integrons do?
Collect many different resistance genes on 1 chromosome
What can move from 1 bacteria to another?
Plasmids
What is a plasmid?
Circular pieces of DNA (but smaller than circular bacterial chromosome)
Encodes genes that can make a pilis- stretches out to another bacteria & DNA (including resistance) is transferred. The resistance still remains in original bacteria.
What carries out Transduction?
Why are they not as good as ICE & plasmids at transferring resistance?
Bacteriophages
These are v specific and only transfer between same strain (unlike plasmids which can transfer between 2 diff types)
What is equally as good as plasmids (pilli) at transferring DNA?
ICE (another genetic vehicle)
What do transponsons do?
1) destroy genes & stop function
2) jump in front of a gene and increase it’s expression
Name a particular type of transposing (jumping gene)
Insertion elements
What can insertion elements do?
Sit either side of a gene & delete it
Lose info
What can add genes?
ICE…..
What is the scientific name for ‘jumping genes’
Transposons
What is an integron?
A collection of genes
As many as 6
Each gene can give resistance to a diff antibiotic
What is the difference between environmental & clinical bacteria?
E doesn’t cause disease
C does
What can collect several intergrons together & increase resistance?
ISRI??
What does ICE stand for?
Integrated Conjugated elements
What are the 2 types of antibiotic resistance?
Intrinsic- already resistant (some clinical, more environment)
Acquired
Examples of naturally resistant bacteria (intrinsic)
B lactamases
SHV (klebsiella)
CMY-2 (citribacter)
Quinolone
Acquired resistance bacterium egs:
SHV
MRSA & VRE (gram +ve)
3 mechanisms how bacteria become resistant:
1) Destroy drug
2) Prevention of drug penetration
3) Alteration of target
What outer membrane mutation cause bacterial resistance?
Porin inactivation
What does MRSA stand for?
Methicillin resistant staph aureus
Via what does MRSA resistance spread?
By bacteria rather than DNA
How do drugs destroy B lactamase?
Open it’s B lactam ring
What are the 3 main types of B lactamase (ESBLs)?
1) SHV & TEM
2) CTXM
3) amp C
What bacteria causes the most blood stream infections?
E. coli
