Pharmacology of GI Infections (Segars)

Question 1

What are the bacteria being discussed for treatment in this lecture?

Answer 1

• • Clostridioides (Clostridium) difficile
• • Campylobacter jejuni
• • Salmonella spp.
• • Shigella spp.

Question 2

What are the treatments used for C. diff?

Answer 2

• • Oral Vancomycin (treatment of choice)

- - Fidaxomicin

Question 3

What is used for C. diff if it is more severe and the patient clinically presents with hypotension or shock, ileum, and megacolon?

Answer 3

Combination of Vancomycin (oral) and Metronidazole

Question 4

What are the treatments for Campylobacter jejuni, Salmonella spp., and Shigella spp. (all the same)?

Answer 4

• • Ciprofloxacin (treatment of choice)

- - Azithromycin

Question 5

What type of antibiotic is Vancomycin?

Answer 5

Glycopeptide

Question 6

What type of antibiotic is Ciprofloxacin?

Answer 6

Fluoroquinolone

Question 7

What type of antibiotics are Fidaxomicin and Azithromycin?

Answer 7

Macrolides

Question 8

Anthelmintic Agents are divided into a _________ group and miscellaneous group.

Answer 8

Benzimidazole (BZA)

***Common ending is -bendazole!

Question 9

What drugs are in the Benzimidazole group of Anthelmintic Agents?

Answer 9

• • Albendazole (treatment of choice)
• • Mebendazole
• • Thiabendazole

Question 10

What drugs are in the Miscellaneous group of Anthelmintic Agents?

Answer 10

• • Ivermectin
• • Nitazoxanide
• • Praziquantel
• • Pyrantel pamoate

Question 11

This Benzimidazole is used cutaneously only due to its high toxicity.

Answer 11

Thiabendazole

Question 12

What is the mechanism of action for BZAs?

Answer 12

– Inhibition of microtubule polymerization via beta-tubulin binding, causing reduced glucose transport.

– Inhibition of mitochondrial fumarate reductase, resulting in immobilization and death.

***These things occur to the parasite!

Question 13

What is the mechanism of action for Ivermectin?

Answer 13

– Binds selectively, and with high affinity, to Glutamate-Gated Chloride ion channels.

– Induces a hyperpolarization resulting in a tonic paralysis of the worms’ nerves and musculature, resulting in immobilization and death.

Question 14

What is an example of what Ivermectin is used for?

Answer 14

Strongyloides stercoralis

Question 15

Ivermectin is used with _________ for lymphatic filariasis.

Answer 15

Albendazole

Question 16

What is the mechanism of action for Nitazoxanide?

Answer 16

Interferes with PFOR (pyruvate:ferredoxin oxidoreductase) enzyme-dependent electron transfer reaction. This is essential to anaerobic energy metabolism.

Question 17

What are examples of use for Nitazoxanide?

Answer 17

• • Cryptosporidium pavum
• • Giardia labmlia
• • Entamoeba histolytica

Question 18

What is the mechanism of action for Praziquantel?

Answer 18

– Increases cell membrane permeability resulting in loss of intracellular calcium, causing massive contractions ending in paralysis of musculature.

– Disintegration of schistosome tegument followed by attachment of phagocytes leading to death.

Question 19

What are examples of use for Praziquantel?

Answer 19

• • Schistosoma spp.
• • Echinococcus granulosus
• • Taenia spp.
• • Diphyllobothrium latum

Question 20

What is the only helminth that has to be used in combination with Albendazole when treated with Praziquantel?

Answer 20

Echinococcus granulosus

Question 21

What is the mechanism of action for Pyrantel pamoate?

Answer 21

– A depolarizing neuromuscular blocker.

– Opens non-selective cation channels and induces a marked, persistent activation of nicotinic-ACh receptors which stimulates release of ACh.

– Inhibits cholinesterase’s, resulting in spastic paralysis of the parasite.

Question 22

What are examples of use for Pyrantel pamoate?

Answer 22

• • Enterobius vermicularis
• • Ascaris lumbricoides
• • Ancylostoma spp.
• • Trichinella spiralis (adult form ONLY)

Question 23

What are the GI focused anti-protozoal agents?

Answer 23

• • Paromomycin
• • Metronidazole
• • Tinidazole

Question 24

Paromomycin is from the _________ family of antibiotics.

Answer 24

Aminoglycoside

Question 25

What is the mechanism of action for Paromomycin?

Answer 25

Exact mechanism for protozoa unknown, but known to work similar to other aminoglycosides (30-S)

Question 26

What are examples of use for Paromomycin?

Answer 26

• • Entamoeba histolytica
• • Diphyllobothrium latum
• • Echinococcus granulosus
• • Taenia spp.
• • Schistosoma spp.

Question 27

These drugs have antibacterial and anti-protozoal activity.

Answer 27

• • Metronidazole

- - Tinidazole

Question 28

What is the mechanism of action for Metronidazole and Tinidazole?

Answer 28

Believed to serve as a pro-drug, activated by electron transfer process creating nitro-radicals which disrupts DNA, killing the organism.

Question 29

What are examples of use for Metronidazole and Tinidazole?

Answer 29

• • Entamoeba histolytica
• • Giardia lamblia
• • Costridioides (Clostridium) difficile

Question 30

Atovaquone-Proguanil are drugs taken together (called Malarone). What are their mechanisms of action?

Answer 30

Atovaquone = Selectively interferes with mitochondrial electron transport and ATP/pyrimidine biosynthesis

Proguanil = Selectively inhibits bifunctional dihydrofolate reductase-thymidylate synthetase enzyme of plasmodia resulting in inhibition of DNA synthesis and depletion of folate cofactors.

Question 31

What are examples of use for Atovaquone-Proguanil?

Answer 31

Plasmodium falciparum

Question 32

For Amebiasis, what organism would be the cause and how would we treat it?

Answer 32

Entamoeba histolytica

Treat with Metronidazole followed by a continued therapy of Paromomycin

Question 33

For Hookworm, what organism would be the cause and how would we treat it?

Answer 33

Ancylostoma spp.
Necator americanus

Treat with Albendazole (can also use Mebendazole)

Question 34

For Roundworm, what organism would be the cause and how would we treat it?

Answer 34

Ascaris lumbricoides

Treat with Albendazole (can also use Mebendazole)

Question 35

For Giardiasis, what organism would be the cause how would we treat it?

Answer 35

Giardia spp.

Treat with Metronidazole (can also use Tinidazole)

Question 36

For Tapeworms in Adult form, what organism would be the cause and how would we treat it?

Answer 36

Diphyllobothrium latum
Taenia spp. (including T. solium, except cysticercosis specific)

Treat with Praziquantel

Question 37

For Tapeworms in Larval forms, what organism would be the cause and how would we treat it?

Answer 37

Echinococcus granulosus – treat with Albendazole + Praziquantel

Taenia solium (Cysticercosis) – treat with Albendazole

Question 38

For Pinworms, what organism would be the cause and how would we treat it?

Answer 38

Enterobius vermicularis

Treat with Mebendazole (can also use Albendazole)

Question 39

For Schistosomiasis, what organism would be the cause and how would we treat it?

Answer 39

Schistosoma spp.

Treat with Praziquantel (+ steroids for neurological disease)

Question 40

For Threadworms, what organism would be the cause and how would we treat it?

Answer 40

Strongyloides stercoralis

Treat with Ivermectin

Question 41

For Whipworms, what organism would be the cause and how would we treat it?

Answer 41

Trichuris trichiura

Treat with Mebendazole (can also use Albendazole)

Question 42

For Trichinellosis, what organism would be the cause and how would we treat it?

Answer 42

Trichinella spp.

Treat with Albendazole (can also use Mebendazole) (+ steroids for severe disease)

Question 43

What is the treatment for Cryptosporidium spp.?

Answer 43

Nitazoxanide

Question 44

What is the treatment for Cyclospora cayetanensis?

Answer 44

Trimethoprim-Sulfamethoxazole (TMP-SMZ), but if patient is sulfa-allergic then use Ciprofloxacin