Antibiotics

Question 1

What are the Mechanisms of Action

Answer 1

Inhibit/interfere with cell wall synthesis
Inhibit protein synthesis
Disrupt unique components of cytoplasmic membrane
Inhibit metabolic pathways
Inhibit nucleic acid synthesis

Question 2

Why can we inhibit protein synthesis?

Answer 2

we have different ribosomes

Question 3

B-Lactam Antibiotics

Answer 3

cephalosporin, monobactams, carbapenems
Inhibits peptidoglycan synthesis
bactericidal

Question 4

Bacteria can produce b-lactamase, makes antibody resistant. What is the B-lactamase inhibitor that can overcome this resistance?

Answer 4

clavulanic acid

Question 5

Glycopeptide Antibiotics

Answer 5

bactericidal
Vancomycin,
Prevents addition of new subunits of PD (peptidoglycan) to a growing cell wall

Question 6

Linezolid

Answer 6

acts on initiation stage, Prevent formation of initiation complex

Question 7

Tetracycline and Tigecycline

Answer 7

block the A site on the ribosome, preventing the binding of amino acids

Question 8

Aminoglycosides

Answer 8

Interfere with proof reading

leads to increase rate of error in synthesis with premature termination

Question 9

Chloramphenicol

Answer 9

Block peptide transfer step of elongation on 50S subunit in bacteria and mitochondria

Question 10

Adverse affects of Chloramphenicol

Answer 10

Aplastic anemia, bone marrow suppression, leukemia, neurotoxicity

Question 11

Benefit of Chloramphenicol

Answer 11

crosses blood brain barrier, if you get meningitis you need something that will cross

Question 12

Macrolides, Clindamycin, and Amino Glycosides inhibit what?

Answer 12

ribosomal translocation

Question 13

Daptomycin and Polymyxins

Answer 13

disrupt cell membrane

Polymixins: interact with phospholipids, poking holes in the cell MB

Question 14

Inhibit Metabolic Pathways

Answer 14

Antifolates
Pyrimidine analogues
Purine analogues

Question 15

Antifolates

Answer 15

we get them from our diet, we don’t make them

impair the function of folic acid leading to disruption in DNA/RNA production

Question 16

Pyrimidine

Answer 16

disrupt their formation and DNA/RNA synthesis

Question 17

Purine

Answer 17

disrupts nucleic acid production

Question 18

Inhibit Nucleic Acid Synthesis: Rifampin

Answer 18

Bind to RNA polymerase, gets the transcript, blocks this at DNA level, Block RNA synthesis

Question 19

Inhibit Nucleic Acid Synthesis: Quinolones

Answer 19

inhibit DNA Synthesis,
Nalidixic acid
Ciprofloxacin

Question 20

Narrow spectrum drugs

Answer 20

limited, good for specific families of bacteria

can be gram negative OR positive

Question 21

Broad spectrum drug

Answer 21

kills everything, ex: amoxicillin
can be BOTH gram -/+
good for drug resistant bacteria that do not respond to each other

Question 22

Why have a broad spectrum?

Answer 22

If you don’t know what to kill, it kills everything (Bad and good)

Question 23

Efficacy: Diffusion susceptibility test (Kirby Test)

Answer 23

Susceptible- Antibiotic works

• Resistant, doesn’t care that antibiotic is there, the bacteria will grow right up to the disk, does not work
• Zone of Inhibition

Question 24

Minimum Inhibitory Concentration:

MIC

Answer 24

Minimum amount we need to inhibit the bacteria (minimum bactericidal)

• Tubes
• eTest

Question 25

MBC: Minimal bactericidal concentration

Answer 25

Topical (superficial infections) - Oral (lower drugs concentrations - IM (intramuscular) - Intravenous IV (highest conc) need to be shot straight into vessel

Question 26

Safety and Side-Effects of MIC and MBC

Answer 26

Toxicity Polymixins & aminogylcocides : can be fatal on kidneys Metronidazole- Black Hairy tongue Tetracycline: complex w/ calcium and get incorporated into growing bone/teeth (white spots on teeth) Allergies: .1% of Americans have anaphylaxis to penicillin

Question 27

What is bacterial transformation

Answer 27

Bacteria that happens to have a resistant gene. And this bacteria is dying, letting its parts out Other bacteria is swimming around and incorporates the bad genes from the environment

Question 28

What is bacterial transduction

Answer 28

Has to do with a virus, phagocytic virus transfers resistance

Question 29

What is bacterial conjugation

Answer 29

Bacteria sex, is it has a pili and the other bacteria is capable to hooking up to the pili they can spread resistance gene (makes copy first) Bacteria to bacteria

Question 30

What is horizontal gene transfer

Answer 30

transfer of genes with the same generation