Drug Resistance pt 1 Flashcards
What is intrinsic antibiotic resistance?
Microbe that has natural resistance to antibiotic
(lack cell walls, endospores)
What is acquired antibiotic resistance?
Microbe gains resistance to antibiotic it was previously susceptible to.
What are the types of acquired antibiotic resistance?
- Spontaneous mutation of chromosome
- Horizontal gene transfer
What are the methods of horizontal gene transfer?
- Conjugation
- Transformation
- Transduction
What is conjugation of acquired resistance?
(How does it work)
- Bacteria with resistant plasmid gene
- connects to susceptible bacteria by pilus
- Transfers plasmid
Are plasmid genes acquired by conjugation incorporated in chromosome?
NO
But daughter bacteria will have resistant plasmid
How does acquired resistance by transformation happen?
- Bacteria with resistant chromosomal gene lyses
- DNA goes into environment
- Another bacteria takes resistance gene and incorporates it
How does acquired resistance by transduction happen?
- Bacteriaphage infects resistant bacteria
- Takes resistant gene
- Bacteriaphage infects another bacteria and incorporates gene
How does this drug resistance mechanism work:
Enzyme that breakdown antibiotic
Microbe acquires gene that encode enzymes to inactivate drugs
What type of mechanism is this:
Beta-lactamase made by bacteria destroy the beta lactam ring of penicillin/cephalosporin.
Enzyme that break down antibiotic
How does this drug resistance mechanism work:
Enzyme that alters antibiotic
Secreted enzyme chemically alter antibiotic
What mechanism is this:
Chlorampehnicol is inactivated when bacteria add acetyl group to it.
Enzyme that alters bacteria
How does this drug resistance mechanism work:
Reduced drug uptake
- Amino acid mutation that changes receptor
- Drugs cannot bind receptor and enter
What type of mechanism is this:
Point mutation in outer membrane transport proteins causes bacterial resistance to aminoglycosides.
Reduced drug uptake
How does this drug resistance mechanism work:
Drug eliminated
- Bacteria have multidrug resistant pumps in cell membrane
- Active transport antibiotics out
How does this drug resistance mechanism work:
Binding site reduced/eliminated
Mutation alters the structure of bacteria that is target of bacteria.
What is this mechanism:
S. aureus become resistant to methicillin due to alteration in cell wall.
Binding site reduced/eliminated
How does this drug resistance mechanism work:
Metabolic pathway turned off
Bacteria turn off/use alternate pathway for metabolism that antibiotic inhibits.
What is this mechanism:
Bacteria use different pathway to produce folic acid when Sulfonamide blocks pathway.
Metabolic pathway turned off
How can antibiotics increase natural drug resistance?
- Naturally drug resistant microbes usually found in population.
- Usually in check by non-drug resistant
- When non-drug resistant killed off, can grow unchecked
How can antibiotics be harmful to your microbiome?
Kill off “good” bacteria that keep pathogenic bacteria in check
What causes viral resistance to occur?
Small genetic changes as virus replicates.
- Spontaneously
- During antiviral treatment
Why do most fungal drug resistances happen?
Antifungal use:
- Too little of a dose
- Not long enough in duration
How can fungi develop resistance?
- Mutates so antifungal does not recognize
- Use alternate metablic pathway drug targets
Where can biofilms form?
What makes them so harmful to treatment?
On any natural/implanted device
100x more resistant than unattached microbe
