Entamoeba Histolytica: Diagnosis and Treatment

Ans. is ‘b’ i.e., Trophozoites in the pus

Ans. is ‘b’ i.e., Erythrophagocytosis

.  The presence of red blood cells in the cytoplasm (erythrophagocytosis) is diagnostic of E. histolytica as it is the only intestinal amoeba to exhibit this characteristic.

Ans. is ‘b’ i.e., Chloroquine

o Chloroquine kills trophozoites of E. histolytica (not cysts). Therefore, it is used in hepatic amoebiasis only.

o All other three drugs are luminal amoebicides – Drugs directly kills trophozites responsible for production of cysts (cysticidal effect).

Ans. is ‘b’ i.e., Diloxanide furoate

Drug therapy for Amoebiasis

1.       Asymptomatic carrier (asymtomatic cyst passers) —)Diloxanide furoate is the DOC.

2.       Invasive amoebiasis (acute colitis, extraintestinal amoebiasis. e.g. liver abscess)

Metronidazole or Tinidazole (DOC) Plus Diloxanide furoate.

Note – In invasive amebiasis, diloxanide furoate (luminal agent) is given to eradicate E. histolytica from the colon and to prevent carrier (cyst passing) state. ,

Ans. is “a’ i.e., Iodine 

• “Amoebic injection is spread by ingestion ref food or water contaminated with cysts. since an asymptomatic carrier may excrete upto 15 million cysts/day. Prevention of infection requires adequate sanitation and eradication of cyst carriage. In high risk areas infection can he minimized by avoidance of unpeeled fruits and the use of Bottled water

o Because cysts are resistant to readily attainable levels of chlorine, disinfection by iodination (Tetraglycine hyperiodide) is recomtnended.” – Harrison

Ans. is ‘c’ i.e., Mostly treated conservatively 

Ans. is ‘a’ i.e., Diloxanide furoate 

Diloxanide furoate is a highly effective luminal amoebicide but has no systemic antiamoebic activity. This is because the furoate ester is hydrolysed in the intestine and the released diloxanide is absorbed. Diloxanide is a weaker amoebicide then its furoate ester and no systemic antiamoebic activity is seen despite its absorption.

Ans. A: USG

It is rapid, inexpensive, and is only slightly less sensitive than CT scan (75-80% sensitivity vs 88-95% for CT scan). Ultrasonography simultaneously evaluates the gallbladder and avoids radiation exposure.

As opposed to scanning with technetium-99m, sonography often can distinguish an abscess from a tumor or other solid focal lesion.

The lesions tend to be round or oval, with well-defined margins, and hypoechoic.

• CT scan is sensitive but the findings are not specific.

The abscess typically appears low density with smooth margins and a contrast-enhancing peripheral rim. The use of injected contrast may differentiate hepatic abscesses from vascular tumors.

• MRI is sensitive, but the findings are not specific. This test provides information comparable with less expensive imaging procedures.
• Technetium-99m liver scanning is useful for differentiating an amebic liver abscess from a pyogenic abscess; however, it is not used as a first-line test.

Because amebic liver abscesses do not contain leukocytes, they appear as cold lesions on hepatic nuclear scanning, with a typical hot halo or a rim of radioactivity surrounding the abscess.

In contrast, pyogenic liver abscesses contain leukocytes and, therefore, typically appear as hot lesions on nuclear scanning.

• Gallium scanning is helpful in differentiating pyogenic abscess (similar to technetium-99m nuclear hepatic scanning) but requires delayed images, which makes the test less helpful.
• Hepatic angiography is only useful to differentiate liver abscesses from vascular lesions.
• Plain chest or abdominal films may show elevation and limitation of motion of the right diaphragm, basilar atelectasis, and right pleural effusion or gas within the abscess cavity.

None of the imaging tests can definitely differentiate a pyogenic liver abscess, an amebic abscess, or malignant disease. Clinical, epidemiological, and serological correlation is needed for diagnosis.

Ans. is ‘a’ i.e., ELISA

Diagnosis of amoebiasis

* Diagnosis is made by :‑

1) Stool examination

* For amoebic colitis definitive diagnosis is made by the demonstration of hematophagous trophozoites.

* Fecal findings are :-

 – A positive test for heme.

 – Paucity (lack) of neutrophils (pus cells).

 – Presence of amebic cysts or trophozoites

 – Charcot-Leyden crystals.

* Charcot-Leyden crystals are also seen in whipworm (trichuris), Ascaris pneumonia, and bronchial asthma.

2) Serological tests

* These tests are most useful for invasive amoebiasis (e.g. amoebic hepatitis/liver abscess).

* Most commonly used test is indirect hemagglutination (IHA). But ELISA is a best (sensitive and specific) test and now replacing IHA.

3) Exploratory technique

* Exploratory puncture is one of the most practical methods for confirming the diagnosis of amoebic liver abscess. The aspirated pus may be examined for the demonstration of trophic forms (trophozoites) of E. histolytica.

* Aspirations from the centre of amoebic liver abscess do not show trophozoites, while aspirates from the margins show trophozoites.