Amebiasis: Difference between revisions
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==Background== | ==Background== | ||
[[File:Amebiasis LifeCycle.gif|thumb|The life-cycle of various intestinal Entamoeba species.]] | |||
*Fecal oral transmission of Entamoeba histolytica cyst | *Fecal oral transmission of Entamoeba histolytica cyst | ||
*Most infection asymptomatic | *Most infection asymptomatic | ||
| Line 17: | Line 18: | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
===Dysentery=== | ===Dysentery=== | ||
*Infectious- [[shigella]], [[salmonella]], [[campylobacter]], [[E.Coli]]. | *Infectious- [[shigella]], [[salmonella]], [[campylobacter]], [[E. Coli]]. | ||
*Noninfectious- [[Inflammatory bowel disease]], [[ischemic colitis]], [[diverticulitis]], AV malformation. | *Noninfectious- [[Inflammatory bowel disease]], [[ischemic colitis]], [[diverticulitis]], AV malformation. | ||
| Line 27: | Line 28: | ||
==Evaluation== | ==Evaluation== | ||
===Labs=== | |||
*CBC | *CBC | ||
*Chem | *Chem | ||
*[[LFTs]] | *[[LFTs]] | ||
*Stool or abscess microscopy | *Stool PCR | ||
**Diagnostic gold standard | |||
**100% sensitive and specific | |||
*Stool or abscess microscopy | |||
**<60% SN; unreliable diagnostic test<ref>Rayan HZ. Microscopic overdiagnosis of intestinal amoebiasis. J Egypt Soc Parasitol. 2005;35(3):941–951</ref> | |||
*Stool, serum, or abscess fluid antigen | *Stool, serum, or abscess fluid antigen | ||
*Indirect hemagglutination (antibody) | *Indirect hemagglutination (antibody) | ||
*CT | |||
===Imaging=== | |||
*Abdominal Ultrasound | |||
**58-98% SN for liver abscess (depending on size/location) | |||
*Abdominal CT | |||
**Alternative to ultrasound; equally effective in identifying abscess | |||
==Management== | ==Management== | ||
| Line 47: | Line 58: | ||
==Disposition== | ==Disposition== | ||
* | *'''Admission''' | ||
**Admit if signs of shock, sepsis, or peritonitis | |||
**Patients with toxic megacolon should be admitted for surgical intervention. | |||
*'''Discharge''' | |||
**Patients who are non-toxic and able to tolerate oral hydration/PO meds can be discharged with outpatient follow-up | |||
==External Links== | |||
*[https://www.merckmanuals.com/professional/infectious-diseases/intestinal-protozoa-and-microsporidia/amebiasis?query=amebiasis Merk Manual - Amebiasis] | |||
==References== | ==References== | ||
Latest revision as of 13:21, 24 July 2021
Background
- Fecal oral transmission of Entamoeba histolytica cyst
- Most infection asymptomatic
- Excystation in intestinal lumen
- Trophozoites adhere and colonizes large intestine forming new cysts or invade the intestinal mucosa to cause colitis or abscesses
- Liver abscess - 10x more common in men
- Incubation period usually 2-4 weeks, but may range from a few days to years
Clinical Features
- Asymptomatic vs. dysentery vs. extraintestinal abscesses
- Intestinal- several weeks of crampy abdominal pain, weight loss, watery or bloody diarrhea
- Liver abscess-fever, cough, RUQ or epigastric pain, right-sided pleural pain or referred shoulder pain +/- GI upset
- Hepatomegaly with tenderness over the liver a typical finding
- Abscess rupture can involve associated peritoneum, pericardium, or pleural cavity
- Extrahepatic amebic abscesses in the lung, brain, and skin are rare
Differential Diagnosis
Dysentery
- Infectious- shigella, salmonella, campylobacter, E. Coli.
- Noninfectious- Inflammatory bowel disease, ischemic colitis, diverticulitis, AV malformation.
Hepatic abscess
- Pyogenic abscess
- Aerobic: Escherichia coli, Klebsiella, Pseudomonas
- Anaerobic: Enterococcus, bacteroides, anaerobic streptococci
- Echinococcosis
- Amebiasis
- Benign cysts/malignancy
- Tuberculosis
- Mycosis
Fever in traveler
- Normal causes of acute fever!
- Malaria
- Dengue
- Leptospirosis
- Typhoid fever
- Typhus
- Viral hemorrhagic fevers
- Chikungunya
- Yellow fever
- Rift valley fever
- Q fever
- Amebiasis
- Zika virus
Acute diarrhea
Infectious
- Viral (e.g. rotavirus)
- Bacterial
- Campylobacter
- Shigella
- Salmonella (non-typhi)
- Escherichia coli
- E. coli 0157:H7
- Yersinia enterocolitica
- Vibrio cholerae
- Clostridium difficile
- Parasitic
- Toxin
Noninfectious
- GI Bleed
- Appendicitis
- Mesenteric Ischemia
- Diverticulitis
- Adrenal Crisis
- Thyroid Storm
- Toxicologic exposures
- Antibiotic or drug-associated
- Inflammatory bowel disease
Watery Diarrhea
- Enterotoxigenic E. coli (most common cause of watery diarrhea)[1]
- Norovirus (often has prominent vomiting)
- Campylobacter
- Non-typhoidal Salmonella
- Enteroaggregative E. coli (EAEC)
- Enterotoxigenic Bacteroides fragilis
Traveler's Diarrhea
- Giardia lamblia
- Cryptosporidiosis
- Entamoeba histolytica
- Cyclospora
- Clostridium perfringens
- Listeriosis
- Helminth infections
- Marine toxins
- Ciguatera
- Scombroid poisoning
- Paralytic shellfish poisoning
- Neurotoxic shellfish poisoning
- Diarrheal shellfish poisoning
Evaluation
Labs
- CBC
- Chem
- LFTs
- Stool PCR
- Diagnostic gold standard
- 100% sensitive and specific
- Stool or abscess microscopy
- <60% SN; unreliable diagnostic test[2]
- Stool, serum, or abscess fluid antigen
- Indirect hemagglutination (antibody)
Imaging
- Abdominal Ultrasound
- 58-98% SN for liver abscess (depending on size/location)
- Abdominal CT
- Alternative to ultrasound; equally effective in identifying abscess
Management
Asymptomatic colonization
- Paromomycin or diloxanide
Colitis
Liver abscess
- Flagyl, tinidazole, paromomycin, or diloxanide
- Consider drainage of abscess by IR if no response to antibiotics in 5 days, abscess > 5cm, or left lobe involvement
Disposition
- Admission
- Admit if signs of shock, sepsis, or peritonitis
- Patients with toxic megacolon should be admitted for surgical intervention.
- Discharge
- Patients who are non-toxic and able to tolerate oral hydration/PO meds can be discharged with outpatient follow-up