Intestinal amoeba Flashcards
Entamoeba histolytica
*Amebic dysentery
Pathogenic GI protozoa (capable of infecting healthy people)
Signs/symptoms: diarrhea, blood and mucus in stool, abdominal cramps, swelling of the colon/abdominal distention. Up to 80% of infections are symptomatic.
Pathogenesis: cysts from contaminated food/water or fecal/oral transmission develop into trophozoites (the protozoal life cycle stage of feeding and reproduction) in small intestine and migrate to colon where they feed on intestinal bacteria; may get into epithelium and cause ulceration and/or spread to liver and cause abscesses.
Work-up: stool sample to check for the protozoa; blood test; liver biopsy; colonoscopy of uncleansed bowel (in severe cases there are ulcers present)
Management: Iodoquinol, Metronidazole
Acanthamoeba castillani
Causes 2 main infections:
–Granulomatous amebic encephalitis (opportunistic infection of brain and spinal cord)
–Keratitis (severe corneal infection common in people who wear contact lenses and have suffered eye trauma)
Signs/symptoms: Granulomatous amebic encephalitis: Headache, nausea, vomiting, abnormal mental status, lethargy; Keratitis: Eye pain, sensitivity to light, tearing, blurred vision
Pathogenesis: Found in soil contaminated with human feces; likely enters through broken skin, inhalation, mucous membranes of the eye
Work-up: Granulomatous amebic encephalitis - biopsy of skin or brain lesion, LP to obtain CSF, CT or MRI to see lesions; Keratitis - examination/culture of corneal scrapings, visualizing the amoeba using special eye microscopy technique
Management: for systemic infection: Amphotericin B; for keratitis: polyhexamethylene biguanide/propamidine isethionate (Brolene); neomycin-polymyxin, gramicidin B
