Amebicidals and Entamoeba Histolytica Life Cycle
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Questions and Answers

Which of these is a clinical use for Diloxanide furoate?

  • In combination after treatment with metronidazole (correct)
  • Dysentery
  • Enteritis
  • Treatment for Amebiasis

    • What is the mechanism of action for Diloxanide furoate ?

  • Acts on the bacterial nucleus
  • Inhibit protein synthesis (correct)
  • Inhibits bacterial protein synthesis
  • Inhibits bacterial protein synthesis and nucleic acid synthesis

    • Which of these is a clinical use of Iodoquinol?

  • Asymptomatic Intestinal Amebiasis
  • In combination after treatment with metronidazole
  • T. vaginalis
  • Treatment for Amebiasis (correct)

    • What is the similarity between Iodoquinol and Diloxanide furoate?

    <p>Both are used to treat asymptomatic intestinal amebiasis (C)</p> Signup and view all the answers

    Iodoquinol is used to treat Amebiasis, but is also used to treat:

    <p>All of the above (D)</p> Signup and view all the answers

    Which adverse reaction can occur when combining metronidazole with disulfiram or disulfiram-like drugs?

    <p>Confusional and psychotic states (C)</p> Signup and view all the answers

    What is the primary clinical use of chloroquine?

    <p>Anti-malarial (C)</p> Signup and view all the answers

    Which pharmacological class does chloroquine belong to?

    <p>Aminoquinoline derivative (B)</p> Signup and view all the answers

    What mechanism of action does chloroquine utilize to inhibit the growth of organisms?

    <p>Increasing internal pH by concentrating within acid vesicles (C)</p> Signup and view all the answers

    What is the bioavailability range of chloroquine upon absorption?

    <p>52-100% (B)</p> Signup and view all the answers

    Which group of drugs could potentially lead to a disulfiram-like reaction when taken with chloroquine?

    <p>Cephalosporins (B)</p> Signup and view all the answers

    Which of the following does NOT describe the metabolism of chloroquine?

    <p>Excreted unchanged in urine (C)</p> Signup and view all the answers

    What percentage of chloroquine is bound to plasma proteins during distribution?

    <p>46-47% (D)</p> Signup and view all the answers

    Which of the following is the primary cause of amebiasis worldwide?

    <p>Entamoeba histolytica (C)</p> Signup and view all the answers

    What is the primary clinical manifestation of symptomatic amebiasis?

    <p>Fulminant Amebic Colitis (B)</p> Signup and view all the answers

    Which drug is classified as a luminal amebicide for treating amebiasis?

    <p>Iodoquinol (B)</p> Signup and view all the answers

    What percentage of the world's population is believed to be affected by amebiasis?

    <p>10% (A)</p> Signup and view all the answers

    Which amebicidal drug is primarily used for cerebral amebiasis?

    <p>Metronidazole (D)</p> Signup and view all the answers

    Which of the following statements about Entamoeba histolytica is incorrect?

    <p>It causes disease only in individuals with prior infections. (A)</p> Signup and view all the answers

    Which infections are effectively treated by histolytica?

    <p>Amebic Colitis and Giardiasis (B), Amebic Liver Abscess and Trichomoniasis (C)</p> Signup and view all the answers

    Which condition is most directly associated with amebic liver abscess?

    <p>Amebic Colitis (D)</p> Signup and view all the answers

    What type of bacteria does metronidazole show effective antibacterial properties against?

    <p>Anaerobic cocci (D)</p> Signup and view all the answers

    Which of the following is NOT a limitation of metronidazole?

    <p>Resistance to anaerobic gram-negative bacilli (A), Ineffective against anaerobic cocci (B)</p> Signup and view all the answers

    Which of the following groups is at greater risk for developing amebiasis?

    <p>People living in crowded conditions (C)</p> Signup and view all the answers

    Which group of bacteria is effectively treated by metronidazole?

    <p>Microaerophilic bacteria (A), Anaerobic spore-forming gram-positive bacilli (D)</p> Signup and view all the answers

    Which of the following conditions is metronidazole primarily ineffective against?

    <p>Aerobic bacterial infections (D)</p> Signup and view all the answers

    What types of infections are classified under extraluminal amebiasis?

    <p>Amebic Colitis and Amebic Liver Abscess (B)</p> Signup and view all the answers

    Which of the following microorganisms is NOT susceptible to metronidazole?

    <p>Staphylococcus spp. (C)</p> Signup and view all the answers

    Which of the following best describes the mode of action of metronidazole?

    <p>Disrupts DNA synthesis in anaerobic microorganisms (C)</p> Signup and view all the answers

    What is the primary mechanism of action for luminal amebicides?

    <p>Act on parasites in the bowel lumen (B)</p> Signup and view all the answers

    Which drug is rapidly hydrolyzed to its active metabolite Tizoxanide?

    <p>Nitazoxamide (C)</p> Signup and view all the answers

    What percentage of Nitazoxamide is bound to proteins?

    <p>99% (B)</p> Signup and view all the answers

    Through which organ is the majority of luminal amebicides excreted?

    <p>Kidneys (B)</p> Signup and view all the answers

    Which of the following is NOT a common adverse effect associated with luminal amebicides?

    <p>Headache (D)</p> Signup and view all the answers

    Which drug listed is considered a prototype for its class?

    <p>Nitazoxamide (A)</p> Signup and view all the answers

    How long is the half-life of the luminal amebicide discussed?

    <p>7 hours (B)</p> Signup and view all the answers

    Which luminal amebicide is considered safe for use during pregnancy?

    <p>Paromomycin (B)</p> Signup and view all the answers

    What is the primary mechanism of action of Chloroquine?

    <p>Raising the pH of the bacterial cell (B)</p> Signup and view all the answers

    What happens to a cell if it cannot generate ATP?

    <p>It will experience ineffective protein transmission. (D)</p> Signup and view all the answers

    Which enzyme is critical for anaerobic metabolism and is affected by Diloxanide furoate's mechanism?

    <p>Pyruvate-ferredoxin oxidoreductase (PFOR) (A)</p> Signup and view all the answers

    What is a consequence of improper enzyme function in a cell?

    <p>Ineffective cellular function (C)</p> Signup and view all the answers

    What does the reduction of metronidazole facilitate?

    <p>Formation of a drug concentration gradient (A)</p> Signup and view all the answers

    Which of the following is true about the function of Emetine?

    <p>It is important for cellular growth. (B)</p> Signup and view all the answers

    What is a consequence of imbalanced pH in bacterial cells?

    <p>Cellular death (C)</p> Signup and view all the answers

    Which statement best describes the role of anaerobic metabolism?

    <p>It is essential for energy generation in the absence of oxygen. (B)</p> Signup and view all the answers

    Study Notes

    Amebicidals

    • Amebiasis affects about 10% of the world's population
    • It is a significant cause of morbidity and mortality due to its invasiveness.
    • It is the third leading parasitic cause of death in humans, after malaria and schistosomiasis
    • It is mostly seen in individuals living in poverty, crowding conditions, and areas with poor sanitation
    • Entamoeba histolytica is the most pathogenic species, capable of causing disease and humans are its only known host.

    Life Cycle of Entamoeba Histolytica

    • Infection begins when mature cysts are ingested.
    • Mature cysts enter the body via the fecal-oral route.
    • Cysts travel down the gastrointestinal tract.
    • They reach the ileum of the small intestine and transform into trophozoites.
    • During the chronic or fulminant stage, trophozoites are the parasitic form capable of invasion.
    • They can invade adjacent structures, such as the liver, lungs, and brain.
    • The trophozoites form cysts that are passed out in the stool.

    Clinical Manifestations

    • Asymptomatic Amebiasis: Infection present but mild or no symptoms
    • Symptomatic Amebiasis: Pathological disease:
      • Amebic Colitis: inflammation of the colon
      • Fulminant Amebic Colitis: severe form of amebic colitis, often life threatening
      • Ameboma: mass of inflammatory tissue
      • Amebic Liver Abscess: Infection of the liver
      • Pulmonary Amebiasis: Infection of the lungs
      • Cerebral Amebiasis (rare): Infection of the brain

    Anti-Amebic Drugs

    • Divided into two main categories:
      • Tissue Amebicides: Used for extraintestinal amebiasis (amebic colitis, liver abscess)
      • Luminal Amebicides: Used for intestinal amebiasis
    • Metronidazole: Effective against extraintestinal amebiasis.
    • Tinidazole: Related to metronidazole, similar activity
    • Emetine: Used for severe extraintestinal amebiasis (liver abscess).
    • Chloroquine: Used for extraintestinal amebiasis.

    Mechanism of Action

    • Metronidazole mechanism of action involves reactive reduction of a nitro group by anaerobic bacteria and sensitive protozoans, producing an active reduction product.

    Pharmacokinetics

    • Rapid absorption, penetrates most tissues, and metabolized by oxidation in the liver.
    • Half-life of around 8 hours, mostly eliminated in the urine.
    • Metronidazole has disulfiram-like effects, so patients should avoid alcohol during and for three days after use.
    • Lithium toxicity can occur with concurrent metronidazole use.
    • Various drugs may interact with each other.

    Adverse Effects

    • Common: Headaches, nausea, dry mouth, metallic taste.
    • Uncommon: Vomiting, diarrhea, abdominal distress
    • Rare: Dysuria, cystitis, sense of pelvic pressure
    • Neurotoxic effects (dizziness, vertigo, encephalopathy, convulsions, incoordination, ataxia, numbness, paresthesia).

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    MOD 18: Amebicidals PDF

    Description

    This quiz delves into the crucial aspects of amebicidals and the life cycle of Entamoeba histolytica. Discover the infection process, its implications on health, and the pathogenicity of this significant parasite affecting millions worldwide. Understand the real-world impact of amebiasis and its relation to sanitation and poverty.

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