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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor= {{YD}} (Reviewed by  {{YD}})
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Microbiology
|MainCategory=Microbiology
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|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Gastrointestinal
|SubCategory=Gastrointestinal
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
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|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Gastrointestinal
|SubCategory=Gastrointestinal
|Prompt=A 25 year old Caucasian male patient presents to the emergency department with bloody diarrhea. He recently arrived to USA from an underprivileged town abroad. Following initial work-up, further investigations reveal multiple flask-shaped ulcers with grey-colored base around the colonic mucosa. Stool analysis and examination reveal the following organism as seen in the image below. What is the best available treatment for this patient?
|Prompt=A 25-year-old man presents to the emergency department with abdominal pain and several episodes of bloody diarrhea. He recently arrived to the USA from an under-served town in Mexico. The patient undergoes GI endoscopy and is found to have multiple flask-shaped ulcers surrounded by a grey-colored base around the colonic mucosa. Stool analysis and examination reveal the following organism as shown in the image below. What is the optimal pharmacological therapy to eradicate the intestinal cysts associated with this patient's condition?
 
[[Image:WBR Entamoeba histolytica.png]]
|Explanation=[[Entamoeba histolytica]] is a parasite that causes bloody diarrhea.  E. histolytica is usually seen in regions with poor sanitation.  Cysts are able to survive in food, in water, and on land.  Cysts are swallowed.  The pathogenic [[trophozoite]] stage develops in the GI tract and exists only in the host and in feces.  [[E. histolytica]] causes characteristic colonic flask-shaped ulcers.  [[E. histolytica]] infections can be complicated by formation of liver abscess, called “amebic liver abscess” that has an “anchovy paste” exudate.  Treatment for [[E. histolytica]] dysentery is [[metronidazole]].
 
Educational Objective:
[[Entamoeba histolytica]] is a parasite that causes dysentery.  It is common in areas with poor sanitation.  It causes typical flask-shaped ulcer in colonic mucosa.  First line treatment for [[E. histolytica]] dysentery is metronidazole.


Reference:
[[Image:WBR0406.png|400px]]
Pritt BS, Clark CG.  Amebiasis. Mayo Clinic Proceedings. 2008;83(10):1154-1160.
|Explanation=''[[Entamoeba histolytica]]'' is a protozoan parasite that causes amebiasis, which is characterized by abdominal pain and bloody diarrhea (dysentery).  ''E. histolytica'' infection is common in regions with poor sanitation. Human infection with ''E. histolytica'' occurs via ingestion of parasitic cysts, which are able to survive in food, water, and on land. The pathogenic [[trophozoite]] stage (mobile form) develops in the GI tract and exists only inside the host and in feces. The majority of individuals ingest cysts and remain asymptomatic; and only a minority of patients manifest with the clinical disease. [[E. histolytica]] infection causes characteristic colonic flask-shaped ulcers with grey-colored bases on colonoscopy (rupture of abscesses in the colonic submucosa). The disease may be further complicated by the development of amebic liver abscess that has an “anchovy paste” exudate. On iodine-stained microscopic analysis (picture above), the parasitic cyst measures 12 to 15  µm. Cysts are typically multinuclear with centrally-located karyosomes and peripheral chromatin. Treatment for [[E. histolytica]] dysentery is by [[metronidazole]]. Tinidazole may be an alternative for metronidazole but it is not used in the United States. Intestinal cyst eradication requires iodoquinol, paromomycin, or diloxanide furoate.
|AnswerA=[[Suramin]] and [[melarsoprol]]
|AnswerA=Suramin and melarsoprol
|AnswerAExp=[[Suramin]], [[melasoprol]], and [[eflornithin]] are used for treatment of [[African sleeping sickness]] that is caused by [[Trypanosoma brucei]] and transmitted by [[Tse Tse]] fly bite
|AnswerAExp=Suramin, melasoprol, and eflornithin are indicated for African sleeping sickness that is caused by ''Trypanosoma brucei'' and transmitted by Tse Tse fly bite
|AnswerB=[[Amphotericin B]]
|AnswerB=Amphotericin B
|AnswerBExp=[[Amphotericin B]] is an antifungal that is helpful in treating systemic mycoses.
|AnswerBExp=Amphotericin B is an antifungal agent that is helpful in treating systemic mycoses.
|AnswerC=[[Sulfadiazine]] and [[pyrimethamine]]
|AnswerC=Sulfadiazine and pyrimethamine
|AnswerCExp=[[Sulfadiazine]] and [[pyrimethamine]] are treatment options for [[Toxoplasmia gondii]].
|AnswerCExp=Sulfadiazine and pyrimethamine are indicated for toxoplasmosis.
|AnswerD=[[Atovaquone]] and [[azithromycin]]
|AnswerD=Iodoquinol
|AnswerDExp=[[Atovaquone]] and [[azithromycin]] are treatment options for [[Babesiosis]].
|AnswerDExp=Iodoquinol, paromomycin, or diloxanide furoate is required for eradication of ''E. histolytica'' cysts.
|AnswerE=[[Metronidazole]]
|AnswerE=Metronidazole
|AnswerEExp=[[Metronidazole]] is the treatment of choice for [[E. histolytica]].
|AnswerEExp=Metronidazole is the treatment of choice for ''E. histolytica''. However, metronidazole cannot eradicate the intestinal cysts, and patients require iodoquinol, paromomycin, or diloxanide furoate for cyst eradication.
|EducationalObjectives=''[[Entamoeba histolytica]]'' is a protozoan parasite that causes amebiasis, which is characterized by abdominal pain and bloody diarrhea (dysentery). It is common in regions with poor sanitation and causes typical flask-shaped ulcer in colonic mucosa. The first line treatment for [[E. histolytica]] dysentery is metronidazole. Addition of iodoquinol, paromomycin, or diloxanide furoate is required for cyst eradication.
|References=Pritt BS, Clark CG. Amebiasis. Mayo Clinic Proceedings. 2008;83(10):1154-1160.<br>
Image Attribution: CDC Public Health Image Library: Amebiasis (ID#:438). Retrieved Feb 17 2015.<br>
First Aid 2014 page 150
|RightAnswer=E
|RightAnswer=E
|WBRKeyword=Microbiology, Entamoeba histolytica, Amebiasis, Protozoa, Parasite, Cyst, Iodoquinol, Abdominal pain, Bloody diarrhea, Diarrhea, Dysentery, Flask-shaped ulcer, Metronidazole, Pharmacological therapy, Treatment, Antimicrobial
|Approved=No
|Approved=No
}}
}}

Latest revision as of 00:27, 28 October 2020
Author [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Microbiology
Sub Category SubCategory::Gastrointestinal
Prompt [[Prompt::A 25-year-old man presents to the emergency department with abdominal pain and several episodes of bloody diarrhea. He recently arrived to the USA from an under-served town in Mexico. The patient undergoes GI endoscopy and is found to have multiple flask-shaped ulcers surrounded by a grey-colored base around the colonic mucosa. Stool analysis and examination reveal the following organism as shown in the image below. What is the optimal pharmacological therapy to eradicate the intestinal cysts associated with this patient's condition?

]]

Answer A AnswerA::Suramin and melarsoprol
Answer A Explanation AnswerAExp::Suramin, melasoprol, and eflornithin are indicated for African sleeping sickness that is caused by ''Trypanosoma brucei'' and transmitted by Tse Tse fly bite
Answer B AnswerB::Amphotericin B
Answer B Explanation AnswerBExp::Amphotericin B is an antifungal agent that is helpful in treating systemic mycoses.
Answer C AnswerC::Sulfadiazine and pyrimethamine
Answer C Explanation AnswerCExp::Sulfadiazine and pyrimethamine are indicated for toxoplasmosis.
Answer D AnswerD::Iodoquinol
Answer D Explanation AnswerDExp::Iodoquinol, paromomycin, or diloxanide furoate is required for eradication of ''E. histolytica'' cysts.
Answer E AnswerE::Metronidazole
Answer E Explanation AnswerEExp::Metronidazole is the treatment of choice for ''E. histolytica''. However, metronidazole cannot eradicate the intestinal cysts, and patients require iodoquinol, paromomycin, or diloxanide furoate for cyst eradication.
Right Answer RightAnswer::E
Explanation [[Explanation::Entamoeba histolytica is a protozoan parasite that causes amebiasis, which is characterized by abdominal pain and bloody diarrhea (dysentery). E. histolytica infection is common in regions with poor sanitation. Human infection with E. histolytica occurs via ingestion of parasitic cysts, which are able to survive in food, water, and on land. The pathogenic trophozoite stage (mobile form) develops in the GI tract and exists only inside the host and in feces. The majority of individuals ingest cysts and remain asymptomatic; and only a minority of patients manifest with the clinical disease. E. histolytica infection causes characteristic colonic flask-shaped ulcers with grey-colored bases on colonoscopy (rupture of abscesses in the colonic submucosa). The disease may be further complicated by the development of amebic liver abscess that has an “anchovy paste” exudate. On iodine-stained microscopic analysis (picture above), the parasitic cyst measures 12 to 15 µm. Cysts are typically multinuclear with centrally-located karyosomes and peripheral chromatin. Treatment for E. histolytica dysentery is by metronidazole. Tinidazole may be an alternative for metronidazole but it is not used in the United States. Intestinal cyst eradication requires iodoquinol, paromomycin, or diloxanide furoate.

Educational Objective: Entamoeba histolytica is a protozoan parasite that causes amebiasis, which is characterized by abdominal pain and bloody diarrhea (dysentery). It is common in regions with poor sanitation and causes typical flask-shaped ulcer in colonic mucosa. The first line treatment for E. histolytica dysentery is metronidazole. Addition of iodoquinol, paromomycin, or diloxanide furoate is required for cyst eradication.
References: Pritt BS, Clark CG. Amebiasis. Mayo Clinic Proceedings. 2008;83(10):1154-1160.
Image Attribution: CDC Public Health Image Library: Amebiasis (ID#:438). Retrieved Feb 17 2015.
First Aid 2014 page 150]]

Approved Approved::No
Keyword WBRKeyword::Microbiology, WBRKeyword::Entamoeba histolytica, WBRKeyword::Amebiasis, WBRKeyword::Protozoa, WBRKeyword::Parasite, WBRKeyword::Cyst, WBRKeyword::Iodoquinol, WBRKeyword::Abdominal pain, WBRKeyword::Bloody diarrhea, WBRKeyword::Diarrhea, WBRKeyword::Dysentery, WBRKeyword::Flask-shaped ulcer, WBRKeyword::Metronidazole, WBRKeyword::Pharmacological therapy, WBRKeyword::Treatment, WBRKeyword::Antimicrobial
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