Inhibit Folic Acid Metabolism

Question 1

What is the mechanism of action for Sulfamethoxazole?

Answer 1

Bacteriostatic; inhibits dihydropteroate synthetase in the folic acid synthesis pathway

Question 2

What is Trimethoprim’s mechanism of action and its effect when combined with Sulfamethoxazole?

Answer 2

Bacteriostatic; inhibits dihydrofolate reductase. Bactericidal when combined with Sulfamethoxazole as they block sequential steps in folic acid synthesis.

Question 3

What is the spectrum of activity for Sulfamethoxazole?

Answer 3

Broad-spectrum: works against both gram-positive and gram-negative cocci

Question 4

What are the common side effects of Sulfamethoxazole/Trimethoprim (Bactrim)?

Answer 4

Skin reactions, hyperkalemia, phototoxicity, urine crystals

Question 5

What is a contraindication for using Sulfamethoxazole/Trimethoprim during pregnancy?

Answer 5

Should be avoided especially in the first trimester due to teratogenic properties

Question 6

What infections is Sulfamethoxazole/Trimethoprim (Bactrim) used to treat?

Answer 6

Urinary tract infections, some gram-positive cocci infections including MRSA, Pneumocystis jirovecii pneumonia

Question 7

What are the common dosing instructions for Sulfamethoxazole/Trimethoprim (Bactrim) for adults?

Answer 7

Bactrim DS (Double Strength) 1 tablet orally twice a day for 3 to 7 days depending on the infection