Sulfonamides, Trimethoprim and Quinolones

Question 1

Sulfonamides tend to be much more soluble at what pH?

Answer 1

Alkaline

Question 2

What enzyme is inhibited by sulfonamide?

Answer 2

Dihyrdopteroate synthase

Question 3

What mechanism is used by sulfonamide for its action against susceptible microorganisms?

Answer 3

Competitive inhibition

Question 4

What drug inhibits dihydrofolate reductase?

Answer 4

Trimethoprim or pyrimethamine

Question 5

Combination or sulfonamide and trimethoprim provides what kind of activity against microorganisms?

Answer 5

Synergistic activity

Question 6

How do you classify sulfonamides?

Answer 6

1. oral, absorbable
2. oral, non-absorbable
3. Topical

Question 7

How do you classify oral, absorbable sulfonamides?

Answer 7

1. short-acting
2. intermediate-acting
3. long-acting

Question 8

What is the drug of choice for Pneumocystiis Jiroveci pneumonia?

Answer 8

Trimethoprim-sulfamethoxazole

Question 9

Sulfisoxazole and sulfamethoxazole is used almost exclusively to treat what?

Answer 9

UTI

Question 10

What is the first line therapy for the treatment of acute toxoplasmosis?

Answer 10

Sulfadiazine in combination with pyrimethamine

Question 11

When giving sulfadiazine with pyrimethamine, you should also administer Folinic acid. Why is that?

Answer 11

To minimize bone marrow suppression

Question 12

What drug is used for ulcerative colitis, enteritis and other inflammatory disease?

Answer 12

Sulfasalazine

Question 13

Mafenide acetate, a sulfonamide used topically for burn sites causes metabolilc acidosis, how?

Answer 13

Inhibition of Carbonic Anhydrase

Question 14

What is the uncommon yet serious adverse reaction of Sulfonamides?

Answer 14

Stevens-Johnson syndrome

Question 15

Sulfadiazine when given in large doses and when fluid intakes is poor can cause crystalluria. How do you treat crystalluria?

Answer 15

Administration of sodium bicarbonate to alkalinize the urine and fluids to increase urine flow

Question 16

What is the mechanism of action of trimethoprim?

Answer 16

Inhibition of bacterial dihydrofolate reductase

Question 17

Is sulfonamide alone bacteriostatic or bactericidal?

Answer 17

Bacteriostatic

Question 18

Is trimethoprim-sulfonamide bacteriostatic or bactericidal?

Answer 18

Bactericidal

Question 19

What causes resistance to trimethoprim?

Answer 19

1. Reduced cell permiability
2. Overproduction of dihydrofolate reductase
3. Production of an altered reductase with reduced drug binding

Question 20

Which is more lipid soluble, therefore larger volume of distribution between sulfamethoxazole and trimethoprim?

Answer 20

Trimethoprim

Question 21

Trimethoprim has more antimicrobial activity in prostatic and vaginal fluids than many other antimicrobial drugs, why?

Answer 21

Trimethorpim is a weak base and concentrates in prostatic and vaginal fluid

Question 22

What are the adverse effects of trimethoprim?

Answer 22

Megaloblastic anemia, leukopenia and granulocytopenia

Question 23

What is the mechanism of action of quinolones?

Answer 23

Inhibition of bacterial topoisomerase I (DNA gyrase) and topoisomerase IV

Question 24

Fluoroquinolones have excellent activity against what organisms?

Answer 24

Gram-negative aerobic

Question 25

Sulfonamides are not given to patiens with G6PD deficiency, why?

Answer 25

Results in acute hemolysis

Question 26

What are the drugs that interact with sulfonamides?

Answer 26

Warfarin and Methotrexate

Question 27

What generation of fluoroquinolone has the highest gram, negative coverage?

Answer 27

2nd generation

Question 28

When do you take fluoroquinolone?

Answer 28

2 before or 4 hours after taking products that contain divalent and trivalent cations

Question 29

What is the drug of choice for prophylaxis and treatment of anthrax?

Answer 29

Ciprofloxacin

Question 30

What is the serious adverse reaction of fluoroquinolones?

Answer 30

Tendonitis and tendon rupture

Question 31

What are the drug interactions of fluoroquinolones?

Answer 31

Theophylline and other methylxanthines

Question 32

What drug has the most activity against microorganisms associated with community-acquired pneumonia?

Answer 32

Levofloxacin

Question 33

What quinolone drugs has the widest specturm of activity?

Answer 33

Gemifloxacin and Moxifloxacin

Question 34

Which drug exhibits postantibiotic effects?

Answer 34

Fluoroquinolones

Question 35

What is postantibiotic effect?

Answer 35

Bacterial growth continues to be inhibited even after the plasma concentration of the drug has fallen below the mean inhibitory concentrations

Question 36

What is the gene in gonococci that causes resistance to quinolones?

Answer 36

gyrA gene