Antibiotics

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

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

Answer 10

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

Question 11

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

Answer 11

Gram +

Question 12

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

Answer 12

Gram -

Question 13

What is the most common drug allergy that exists?

Answer 13

Penicillin allergy (urticaria, redness, etc.)

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

What adverse reactions can occur from vancomycin?

Answer 16

“Red-neck” Syndrome - neck flushing from histamine release - irritating to tissues
10% adverse reactions
Ototoxicity
Nephrotoxicity
Chills/fever

Question 17

How do cell membrane disruptors work?

Answer 17

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

best action: Gram (-)

Question 18

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

Answer 18

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

Question 19

What drug classes are protein synthesis inhibitors?

Answer 19

Tetracyclines
Macrolides
Aminoglycosides
etc.

Question 20

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

Answer 20

4-ring structure
Bacteriostatic

Question 21

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

Answer 21

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

Question 22

Why are tetracyclines not given to children?

Answer 22

Abnormal bone development

Question 23

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

Answer 23

Erythromycin
Azithromycin (short course, 4-5 days)

Question 24

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

Answer 24

Rifamycin

Question 25

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

Answer 25

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

Question 26

Which drugs are bacterial DNA/RNA synthesis inhibitors?

Answer 26

Rifamycin Fluoroquinolones (Cipro, Levaquin, & floxins)

Question 27

Which drugs are inhibitors of folic acid synthesis?

Answer 27

Sulfonamides Trimethoprim

Question 28

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

Answer 28

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

Question 29

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

Answer 29

Pneumocystitis & toxoplasmosis Often paired with Trimethoprim

Question 30

What antifungals need to be known?

Answer 30

Imidazole (ketoconazole) & Lamisil

Question 31

What 2 antiprotozoan agents need to be known?

Answer 31

Hydroxychloroquine & Metronidazole (Flagyl)

Question 32

What is metronidazole used for?

Answer 32

Giardia & trichomoniasis

Question 33

What are the side effects of metronidazole?

Answer 33

Black “hairy” tongue (can last a year) Birth defects Cancer

Question 34

What drug is used to treat river blindness roundworm?

Answer 34

Ivermectin can also treat COVID19?

Question 35

How does bacterial antibiotic resistance develop? Describe extrachromosomal mutation.

Answer 35

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

Question 36

How does premature termination of antibiotics propagate antibiotic resistance?

Answer 36

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 37

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

Answer 37

Fecal Transplant.

Question 38

Penicillin, ampicillin, amoxicillin target?

Answer 38

cell wall

Question 39

cephalosporin target?

Answer 39

cell wall

Question 40

polymyxin & Daptomycin target?

Answer 40

Cell membrane

Question 41

neomycin target?

Answer 41

protein synthesis

Question 42

what classification is ketoconazole?

Answer 42

anti-fungal

Question 43

niclosamide & permethrin target?

Answer 43

parasitic worms Permethrin - LICE Niclosamide - tapeworm

Question 44

Polymysins are considered?

Answer 44

polypeptide antibiotics and act like detergent, bind to phospholipids, effective against gram-negative bacteria

Question 45

cephalosporins

Answer 45

more resistant to B-lactamase broader spectrum first generation: better gram + activity uses: UTI, Staph, alternative to PCN (less allergy)