Antibiotics (Exam V)

Question 1

What color do gram + bacteria stain with? Why is this?

Answer 1

• Purple-Blue (Techoic acid stains to the peptidoglycan)

Question 2

What makes up the cell wall in bacteria?
In which bacteria is this cell wall much bigger?

Answer 2

• Peptidoglycan
• Gram+ bacteria

Question 3

What color do gram - bacteria stain with?
What characteristics do gram- bacteria have?

Answer 3

• Reddish-orange
• Second outer membrane on top of a thinner cell wall
• Gram - bacteria have lipopolysaccharides in their outer membrane.

Question 4

What occurs if too many gram - bacteria are killed off too quickly?
Why is this?

Answer 4

• Endotoxic Shock Syndrome
• Massive release of lipopolysaccharides that are converted into endotoxin.

Question 5

What shape do gram + bacteria often have?
What about gram - bacteria?

Answer 5

• Gram + = spherical (cocci)
• Gram - = rods (everything else)

Question 6

Differentiate bactericidal & bacteriostatic.

Answer 6

Bactericidal = kills bacteria
Bacteriostatic = prevents replication/growth

Question 7

What is the most broad spectrum antibiotic class?
Why are these safer for humans?

Answer 7

• Ribosome Protein Synthesis Inhibitors
• Inhibit ribosomes 50S & 30S that humans don’t have.

Question 8

What types of ribosomes do bacteria have?

Answer 8

• 50S & 30S (& 70S)

Question 9

What types of ribosomes do humans have?

Answer 9

• 40S, 60S, & 80S

Question 10

What structure is highlighted in red below?

Answer 10

β-lactam ring

Question 11

How do β-lactam containing ABX’s inhibit cell wall synthesis?

Answer 11

• The β-lactam ring binds & blocks the enzymes that cross link the peptidoglycans that form the wall.

Question 12

What drug is indicated by 1 on the figure below?

Answer 12

Penicillin

Question 13

What drug is indicated by 2 on the figure below?

Answer 13

Cephalosporin

Question 14

What type of bacteria do cell wall inhibitors work best on?

Answer 14

Gram +

Question 15

What type of bacteria do cell membrane disruptors work best on?

Answer 15

Gram -

Question 16

What is the most common drug allergy that exists?

Answer 16

• Penicillin allergy (urticaria, redness, etc.)

Question 17

What are carbapenems useful for?
What are they the drug of choice for?

Answer 17

• β-lactamase bacteria & when CNS penetration is needed.
• Enterobacter (drug of choice)

Question 18

What drug is good for penicillin resistant gram + bacteria (MRSA)?
How does it work?

Answer 18

• Vancomycin
• Binds to amino acids & prevents cross-linking of peptidoglycans.

Question 19

What adverse reactions can occur from vancomycin?

Answer 19

• “Red-neck” Syndrome - neck flushing from histamine release
• Ototoxicity
• Nephrotoxicity
• Chills/fever

Question 20

How do cell membrane disruptors work?

Answer 20

• Act as detergents essentially. Bind to phospholipids in membrane & create pores.

Question 21

Can Polymixin be used systemically to treat infections? Why or why not?

Answer 21

• Last resort for resistant gram - strains
• Very neuro & nephro toxic

Question 22

What drug classes are protein synthesis inhibitors?

Answer 22

• Tetracyclines
• Macrolides
• Aminoglycosides
• etc.

Question 23

What kind of structure do tetracyclines have?
Are they bacteriostatic or bactericidal?

Answer 23

• 4-ring structure
• Bacteriostatic

Question 24

What is the biggest side effect of tetracyclines when used with adults?
Why is this?

Answer 24

• N/V/D & gastric upset.
• Very broad spectrum & can destroy normal intestinal microbiota

Question 25

Why are tetracyclines not given to children?

Answer 25

- Abnormal bone development

Question 26

Name the two macrolides discussed in lecture. What advantage does one have over the other?

Answer 26

- Erythromycin - Azithromycin (short course, 4-5 days)

Question 27

What drug, discussed in lecture, binds to bacterial RNA polymerase?

Answer 27

- Rifamycin

Question 28

How do Fluoroquinolones work? What characteristics do these drugs have?

Answer 28

- Inhibition of DNA gyrase - Excellent gram - activity - Good gram + activity

Question 29

Which drugs are bacterial DNA/RNA synthesis inhibitors?

Answer 29

- Rifamycin - Fluoroquinolones (Cipro, Levaquin, & floxins)

Question 30

Which drugs are inhibitors of folic acid synthesis?

Answer 30

- Sulfonamides - Trimethoprim

Question 31

What is the mechanism of action of bacterial folic acid synthesis inhibitors?

Answer 31

- Prevent conversion of PABA into DHF (dihydrofolic acid) → → folic acid.

Question 32

What are sulfonamides often used for? What are they often used with?

Answer 32

- Pneumocystitis & toxoplasmosis - Often paired with Trimethoprim

Question 33

What antifungals need to be known?

Answer 33

- Imidazole - Amphotericin - Lamisil

Question 34

What three antiprotozoan agents need to be known?

Answer 34

- Quinine - Hydroxychloroquine - Metronidazole (Flagyl)

Question 35

What is metronidazole used for?

Answer 35

Giardia & trichomoniasis

Question 36

What are the side effects of metronidazole?

Answer 36

- **Black "hairy" tongue** (can last a year) - Birth defects - Cancer

Question 37

What drug is used to treat river blindness roundworm?

Answer 37

- Ivermectin

Question 38

How does bacterial antibiotic resistance develop? Describe extrachromosomal mutation.

Answer 38

- Chromosomal mutation - Extrachromosomal mutation (f-plasmid forms f-pilli with another bacteria thus transferring its resistance.

Question 39

How does premature termination of antibiotics propagate antibiotic resistance?

Answer 39

- Highly resistant bacteria take longer to be killed by antibiotic so if stopped early then the highly resistant ones are the only ones left that can reproduce.

Question 40

What can be used for a horrible C-diff infection to restore normal intestinal flora?

Answer 40

- Fecal Transplant.