what is amoebic dysentery? Its Best Overview and More

what is amoebic dysentery?


  • Dysentery is a clinical condition of multiple etiology, characterized by the frequent passage of blood-stained, mucoid stools.
  • The two common types of dysentery are bacillary and amoebic.
  • The causative organism of amoebic dysentery is Enamecha fastolitica.
what is amoebic dysentery? Its Best Overview and More

Amoebic dysentery:-

Amoebiasis is an infection due to intestinal protozoan Entamoeba histolytica, usually, patients (90%) are asymptomatic whereas only 10% of patients are with symptoms ranging from dysentery to an amebic hepatic abscess.

Amoebic dysentery transmission and Life cycle:-

E. histolytica exists in 2 forms

  • Cyst for is is dormant form, found in the lumen, shed along with stool, and is responsible for Transmission of infection.
  • Trophozoite form is motile and found in the lumen as well as extraluminal sites like Porto hepatic circulation causing a Hepatic abscess.

E. histolytica enters the human body via the feco-oral route, due to ingestion of viable cysts in contaminated food, water, and hands. When cysts reach the small intestine, motile trophozoites are released by enzymatic action on cysts. Trophozoites mostly remain as commensals in the large intestine and after encystation, infectious cysts are again shed with stool.

Extraintestinal amoebiasis:-

The trophozoites of E. histolytica, after invading through the bloodstream, reaches to liver, lung, brain, etc. causing abscess formation. Commonest being the hepatic amoebiasis, clinically presented as shoulder pain (due to irritation of phrenic nerve) with tenderness in the right hypochondriac region accompanied by jaundice, nausea vomiting, fever, and also diarrhea with tenesmus alternating with constipation. Anchovy sauce appearance of blood from a hepatic abscess is seen in ultrasonography-guided drainage.

Amoebic dysentery symptoms:-

Symptoms can appear 10 days after exposure and infection by the parasite.

Clinical features of infection include:-

  1. Watery diarrhea with blood or mucus or both.
  2. Nausea or vomiting or both
  3. Abdominal pain
  4. Fever
  5. Chills
  6. Bleeding per rectum
  7. Loss of appetite

Laboratory diagnosis is made by finding E.hystolytica cysts shed in 2-3 samples of fresh stool.

Amoebic dysentery treatment and Drug used:-

Tab Metronidazole 400 mg 8 hourly x 7days
Tab Diloxanide Furoate 500 mg 8 hourly x 10 days
Tab Paracetamol 500 mgs S.O.S if Fever
Oral rehydration salt solution, one sachet to be dissolved in one liter of boiled andcooled water and to be taken within 24 hours

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WHO-recommended oral rehydration salts

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  • A Nitraimidazole derivative.
  • Rapidly absorbed orally but can be given as IV infusion or serious infection.
  • Oral bioavailability is 70-80% Food does not affect its absorption.
  • Metabolized mainly in the Liver, the Nitro group gets bioactivated by reduction to form reactive cytotoxic product.
  • Plasma 11/2 is 8 hrs, increased in patients with impaired renal and hepatic function.
  • It is excreted primarily by urine.

Mechanism of Action:-

  • Anaerobic protozoan parasites possess the enzyme Pyruvate-ferroan oxidoreductase, which is not found in mammalian cells. This enzyme is involved in energy production through the electron transfer chain.
  • The nitro group of Metronidazole serves as an electron acceptor and gets reduced.
  • Reduced Metronidazole is cytotoxic to anaerobic protozoa and bacteria by disrupting replication, transcription, and repair process of DNA that results in cell death.
  • In aerobic organisms, aerobic environment prevents the reduction of metronidazole, is seen against the aerobic organisms.
  • It is also effective against other anaerobic organisms.


  • Gradnerella, Gardenella vaginalis infection(ziarial vaginosis)
  • H. pylori-induced Peptic Uleer
  • Pseudomembranous colitis
  • Trichomoniasis
  • Amoebiasis
  • Also Anaerobic bacterial infections like Bacteroides
  • Oral infection
  • Pelvic inflammatory infection
Adverse effects:-
  • GI: nausea, vomiting, epigastric distress
  • Metallic taste
  • CNS: vertigo, dizziness, headache, numbness of extremities (less frequent), seizures in higher dose.
Drug Interaction(metronidazole and alcohol):-
  • Alcohol it Inhibits the Aldehyde Dehydrogenase enzyme, so shows a Disulfiram-like reaction.
  • Should be avoided during Pregnancy (Category B)and persons suffering from neurological complications.

Diloxanide Furoate:-

  • An effective Luminal Amoebicide, but not active against tissue trophozoites.
  • Effective in inild intestinal amoebiasis and asymptomatic cyst passers.
  • Kills luminal trophozoites that produces cysts.
  • Being Ester gets hydrolyzed in the gut to diloxanide and furoic acid.
  • About 80-90% of free Diloxanide gets absorbed systemically but has no systemic antiamoebic action and 10-20%, which remain unabsorbed in out, is a real antiamoebic substance.
  • Well tolerated and safe drug.
  • Diloxanide Turvate destroys trophozoites of F. histolytica and prevents amoebic cyst formation. The exact mechanism of diloxanide is unknown. It is structurally related to chloramphenicol and may act in a similar fashion by blocking protein synthesis.
Adverse Effect:-
  • Diloxanide generally has mild side effects. Side effects may include flatulence, vomiting, itchiness.
  • During pregnancy it is recommended after the first trimester.
Other drugs of Amochiasis:-
  • Paromomycin
  • Chloroquine
  • Tinidazole
  • Secnidazole

These drugs must be followed by luminal acaricide for 10-20 days to abolish the luminal cycle.

What is dysentery?

Dysentery is a clinical condition of multiple etiology, characterized by the frequent passage of blood-stained, mucoid stools.
The two common types of dysentery are bacillary and amoebic.
The causative organism of amoebic dysentery is Enamecha fastolitica.

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