GASTROENTEROLOGY ARTICLE OF THE WEEK
June 12, 2003
Haque R, Huston CD, Hughes M, et al. Amebiasis. N Engl J Med 2003;348:1565-1573.
1. Colonic amebiasis
a. the colon mucus layer protects against invasion by amebae
b. Gal/GalNac is required for colonization of the large intestine
c. chronic amebiasis rarely occurs as the immune response promptly kills the
amebae
d. Mucosal IgA response to Gal/GalNac may protect against subsequent
infections
2. Amebic liver abscess
a. is 10X more common in men than women
b. fever is a rare finding, when present, suspect bacterial abscess
c. normal alkaline phosphatase suggests an acute abscess
d. lesions are usually multiple and in both lobes
e. stool ameba antigen detection is positive in <50% f patients with amebic liver
abscess
f. cyst aspiration with microscopic examination of the fluid will usually reveal the
presence of amebae
3. Indications for cyst aspiration include
a. location in the right lobe
b. size >5 cm
c. lack of clinical response after 5-7 days of therapy
d. left lobe location
e. to detect the presence of amebae
4. Treatment of amebiasis
a. non-invasive infection can be treated with paromomycin
b. metronidazole is the drug of choice for invasive disease
c. 40% to 60% of patients treated with nitroimidazoles have persistent parasites
in the intestinal lumen
d. paromomycin should be initiated together with metronidazole when treating
invasive amebiasis
True or false
5. Fever associated with bloddy diarrhea are common presenting signs of colonic amebiasis
6. HIV increases the risk for invasive amebiasis
7. Asymptomatic carriage of Entamoeba hystolytica does not need to be treated.
8. Corticosteroids may increase the severity of intestinal amebiasis and predisposes to toxic megacolon.
9. The presence of serum antibodies against ameba is diagnostic of acute invasive intestinal amebiasis.