Antimicrobial Drugs

Question 1

Broad vs narrow

4 groups

Answer 1

Gram+, gram -, mycobacterium, chlymidia/rickettsia

Broad: used for unknowns and superdrugs

Narrow: less likely to disrupt flora, used when target known,

Sometimes don’t know cause of infection…
Often difficult or costly or timely to determine cause.

Question 2

How is the anti microbial drugs administered?

Answer 2

Systemic: body wide
Topically: placed on skin
Locally: in specific area
Orally: taken by mouth
   Is it of absorbed or digested?

Question 3

List 5 ways antimicrobials work?

Answer 3

Affect cell wall synthesis
Affect protein synthesis 
Act on plasma membrain
Inhibit metabolic pathways
Inhibit nucleic acid synthesis

Question 4

Antimicrobials that effect cell wall

Answer 4

More effective on gram+
Beta-lactam rings prevent cross links in peptidoglycan
Drug resistance cause by genes for lactamase( breaks down beta-lactamase ring)

Penicillin, vancomycin, bacitracin (topical drug)

*ideal target as only effects bacteria and no eukaryote cells

Question 5

Antimicrobials that affect protein synthesis

Answer 5

Broad spectrum drug
Affect 70s ribosome as it’s different than eukaryote 80s ribosome
2 sub units in ribosome that can be targeted

Can be difficult to use as eukaryote have 70s ribosomes in mitochondria inside the cell

Tetracycline, chloramphenicol

Question 6

Antimicrobials that effect plasma membrains

Answer 6

Not often used because. Our plasma membranes are similar to prokarcates.

Amphotracin B (drug)
Polymixin  found in antibiotic ointment

Question 7

Antimicrobials that inhibit metabolism

Answer 7

Stop making essential components.
Sulfa drugs stop folic acid pathway (we do not make this so doesn’t effect us)
These often work as competitive inhibitors

Question 8

Antimicrobials that inhibit nucleic acids

Answer 8

Only affect prokaryotes or fungi
Rifampin (used to treat TB and Nesseria menigitidis)
Can cause body fluids to turn orange or red
Possibly prevent virus attachment

Question 9

How do you choose what drug to use? 8 things to consider

Answer 9

1. Availability
2. Inexpensive
3. Chemicals stable (need refrigeration)
4. Easily administered
5. Non toxic
6. Non allergic
7. Selectively toxic to the organism you want dead
8. Efficacy ( MIC testing or Kerry Bauer for fingering out concentration)

Question 10

Drug resistance

Answer 10

Drug resistance happens because of evolution and natural selection.
Microbes multiply rapidly and can have billions in a small area

Resistance Occurs by

1. new mutations (random)
2. Horizontal transfer

Question 11

5 mechanism of antimicrobials resistance

Answer 11

1. Make a protein to break down drug (beta lactamase)
2. Cell membrane changes so drug can not enter cell
3. Cell changes receptors so drug can’t bind
4. Cell changes or alters metabolic pathway
5. Cell pumps drug out of cell

Question 12

How to slow down antimicrobial resistant bacteria

Answer 12

1. Use enough drug for long enough
2. Use two or more drugs to promote synergism
   ( must be careful with this as antagonism can happen)
3. Use only when needed (70% of antimicrobial not for infections)
4. Develop new ones

Question 13

Superbugs

Answer 13

MSRA: methicillin resistant staphylococcus aureus
VISA: vancomycin intermediate resistance S. Aureus

VRE: vancomycin resistance enterococcus
From fecal contamination or gut surgery

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