Difference Between Amoebic and Bacillary Dysentery

Main Difference – Amoebic vs Bacillary Dysentery

Amoebic Dysentery and Bacillary Dysentery are two medical conditions which affect the gastrointestinal system. These two terms are often used interchangeably if there is a lack of pathological and microbiological analysis, which is necessary in order to differentiate one from the other.

Dysentery, in general, is defined as an inflammatory disorder which affects the intestines, more specifically the colon, resulting in high fever, severe diarrhea, and abdominal pain. Lack of good hygiene and poor sanitation are two of the most significant causes behind the spread of dysentery, which is mainly a result of contaminated food and beverage consumption.

Both these conditions can be diagnosed by taking a proper history of the patient about the duration of symptoms, the severity, and a thorough physical examination.

A culture test of stool samples will be used to detect and identify the real causative agent, which will then confirm the diagnosis for a greater extent. In some patients, a sample of the mucus from the colon lining or a tissue sample of the colon will also be obtained for further evaluation.

Blood tests and serum electrolytes levels will be assessed to identify the risk of dehydration as a result of the on-going fluid loss. Additionally, other screening tests such as x-rays, CT scans, ultrasound examinations, and MRI can be used in some patients who are at a risk of developing complications associated with lungs or the liver, especially in the case of amoebic dysentery.

This article looks at,

1. What is Amoebic Dysentery? – Cause, Signs and Symptoms, Method of Diagnosis and Treatment 

2. What is Bacillary Dysentery? – Cause, Signs and Symptoms, Method of Diagnosis and Treatment 

3. What is the difference between Amoebic and Bacillary Dysentery?Difference Between Amoebic and Bacillary Dysentery - Comparison Summary

What is Amoebic Dysentery (Amoebiasis)

Amoebic Dysentery is  defined as a type of Dysentery caused by Amoebic organisms resulting in a great amount of fluid loss from the body. Entamoeba histolytica is the commonest ameba, causing amoebic dysentery; it enters the body in the form of a cyst via contaminated food or beverages. This cyst breaks into fragments after entering into the digestive tract and converts into an active organic form known as Trophozite. The disease arising this way would then invade the tissue linings of the colon or may even penetrate into the bloodstream, leading to severe conditions in lungs, liver and other important organs of the body. This invading process of Amoebic Dysentery is known as metastatic amebiasis.

The symptoms which develop slowly are characterized by diarrhea associated with blood mixed stools (blood dysentery). Rising of temperature will only be noted if complications such as liver abscesses are developed in the course of the disease.

Chronic amoebic dysentery can result in severe inflammation of the colon, referred to as necrotizing colitis and, an increased risk of colon rupture.

As far as the treatment for Amoebic dysentery is considered, it is important to start the treatment as soon the diagnosis. Antimicrobial drugs such as metronidazole (Flagyl), Diloxide (diloxanide furoate), and Iodoquinal, are the recommended therapeutic agents which are known to improve the symptoms. Severe amoebiasis is usually treated with Dehydroemetine.Difference Between Amoebic and Bacillary Dysentery

What is Bacillary Dysentery

This is a type of Dysentery caused by a group of bacteria of the genus, Shigella, which is why this condition is also known as Shigellosis or Shigella dysentery. The four major strains of bacteria under the genus Shigella include S. dysenteriae, S. boydii, S. sonnei, S. flexneri and all of them could cause dysentery.

The bacteria, invading the colon tissues will then secrete a harmful toxin, named Enterotoxin which attacks the intestinal lining of the colon, resulting in pain and diarrhea.

Patients with the condition will usually experience symptoms such as diarrhea with or without blood, tenesmus, mild to high fever, rectal pain and abdominal cramps which could last for weeks to months. Furthermore, chronic bacillary dysentery may cause severe conditions like hemolytic uremic syndrome which can result in kidney failure.

Bacillary dysentery is usually treated with antibiotics such as Ciprofloxacin, Trimethoprim-sulfamethoxazole, and Nalidixic acid. More importantly, Anti-diarrheal medications such as Diphenolate, Loperamide are strongly prohibited in these cases since they are known to exacerbate the situation.

Main Difference - Amoebic vs Bacillary Dysentery

Photomicrograph of Shigella sp. in a stool specimen

Difference Between Amoebic and Bacillary Dysentery


Amoebic dysentery (amoebiasis) is mainly caused by an invasive protozoa parasite called Entamoeba histolytica.

Bacillary Dysentery (Shigellosis) is a bacterial disease caused by a species of bacteria known as Shigella sp.

Signs and Symptoms

Amoebic dysenteric patients will suffer 6-8 episodes of loose motions per day.

Those with Bacillary type will have more than 10 episodes of bloody diarrhea.


In the case of amoebic dysentery, the amount of stool is relatively copious when compared with the amount of stool produced in bacillary dysentery.

Amoebic dysentery stools will be dark in color with an offensive odor.

In the case of Bacillary dysentery, the stools will have the color of fresh blood and is usually odorless.

Therefore, it is important to get a clear history about the color of stools and associated smell in order to come to a better clinical diagnosis.

Microscopic Examination

As far as the assessment of stools with the help of a microscope is concerned,

The ones in amoebic dysentery will indicate RBCs, clumped together with a reddish-yellow color, numerous eosinophils, few pus cells and macrophages. Furthermore, cell types known as Charcot-Leyden (C-L) crystals and Pyknotic bodies will be present only in Amoebic type.

The ones in bacillary dysentery will have discrete amounts of RBCs, which will often form rouleaux, fewer eosinophils, numerous pus cells, and macrophages. Further,  the bacillary type will only have ghost cells.

It is quite important to know these differences in order to come to an accurate microbiological diagnosis.


As far as the treatment is concerned, amoebic dysentery can be intervened with anti-protozoal drugs.

The bacillary dysentery can be treated effectively with antibiotics.

Both conditions should be managed with proper fluid replacement since they can result in severe dehydration, which can be life-threatening.

Image Courtesy:

“Amebiasis LifeCycle” By CDC (Public Domain) via Commons Wikimedia 

“Shigella stool” By Centers for Disease Control and Prevention Public Health Image Library – Centers for Disease Control and Prevention Publich Health Image Library, (Public Domain) via Commons Wikimedia

About the Author: Embogama

Embogama is a passionate freelance writer for several years. Her areas of interest include general medicine, clinical medicine, health and fitness, Ayurveda medicine, psychology, counseling and piano music