Sulfonamide Antimicrobial Agents Flashcards Preview

Pharmacology Test #2 > Sulfonamide Antimicrobial Agents > Flashcards

Flashcards in Sulfonamide Antimicrobial Agents Deck (25)
Loading flashcards...
1

What is inhibited competitively by the sulfonamides?

the incorporation of p-aminobenzoic acid (PABA) into the folic acid nucleus

2

The sulfonamides inhibit?

dihydropteroate synthase

3

Why do sulfonamides have selective toxicity for bacterial cells as opposed to mammalian cells

mammalian cells utilize preformed folates in the diet and some bacterial cells are required to make their own folic acid

4

How can the antibiotic activity of sulfonamides be reversed?

by adding large quantities of PABA to the diet

5

Sulfonamides in general inhibit?

gram (+) and gram (-) bacteria
nocardia
Chlamydia trachomatis
some protozoa and fungi
enteric bacteria such as E. coli, Klebsiella, salmonella, shigella and enterobacter

6

Why are sulfonamides usually used in combination

the resistance factors are too widespread for these drugs to be used in a single drug therapy

7

What is the antifungal activity of trimethoprim-sulfamethoxazole important for?

the treatment of AIDS-infected patients that have developed Pneumocystis carinii (jiroveci)

8

What does trimethoprim inhibit?

dihydrofolate reductase
(so combination with sulfamethoxazole inhibits sequential steps in the biosynthesis of tetrahydrofolic acid)

9

Most popular sulfonamide

sulfisoxazole (broad spectrum antibiotic activity)

10

Sulfisoxazole and sulfamethoxazole are mainly used to treat

simple urinary tract infections

11

used as a cream to treat vaginal infections by Gardnerella vaginalis

1:1:1 combination of sulfabenzamide, sulfacetamide, and sulfathiazole (triple sulfas)

12

Triple sulfas-phenylpropanolamine-pheniramine is also used to treat

used orally in tablet/suspension to treat sinus and throat infections

13

What is sulfasalizine used to treat

ulcerative colitis and Crohn's disease

14

Direct administration of salicylates, including 5-aminosalicyclic acid is?

irritating to the gastric mucosa

15

What is sulfadoxine?

long-acting sulfonamide used with pyrimethamine to prevent and treat malaria

16

What is pyrimethamine

inhibitor of Plasmodium falciparum dihydrofolate reductase

17

first-line chemotherapy to treat acute toxoplasmosis

sulfadiazine in combination with pyrimethamine

18

All sulfonamides and their derivatives are?

cross-allergenic

19

sulfonamide derivates in use include

carbonic anhydrase inhibitors, thiazides, furosemide, sulfonylurea hypoglycemic agents etc

20

Most common adverse reactions of sulfonamides

allergic reactions - present as rash, photosensitivity, and drug fever

21

potentially fatal adverse reaction of sulfonamides

Stevens-Johnson syndrome: rare skin and mucous membrane rash tha tis potentially fata

22

Other adverse reactions of sulfonamides

crystalluria and hematopoietic disturbances: asplasmic anemia, granulocytopenia, and thrombocytopenia
anorexia, nausea, and vomiting occurs in 1-2%

23

Resistance to sulfonamides occurs through the following mechanisms

1. mutations that cause overproduction of PABA
2. mutations in dihydropteroate synthase that decreases its affinity for the sulfonamides
3. mutations that result in a decrease in cell permeability to the sulfonamides

24

Why do you always give sulfonamides in combination

resistance is very common
resistance to combination therapy targeting two enzymes in highly reduced since the microorganism wold have to carry mutations in two enzymes

25

What happens when the dihydrofolate reductase (DHFR) gene is mutated

enables the expressed enzyme to be active in the presence of drug through a decreased binding affinity of trimethoprim