A 24-year-old man comes to the emergency department due to bloody diarrhea. His symptoms began 10 days ago with episodic abdominal discomfort and loose stools. The symptoms have progressively worsened, and he has had 6-8 stools mixed with blood and mucus over the past 2 days. The patient recently returned from a 2-week trip to Egypt and felt well while traveling. Temperature is 38 C (100.4 F), blood pressure is 120/70 mm Hg, and pulse is 86/min. The abdomen is soft with mild tenderness on palpation of lower quadrants. There is no guarding or rebound tenderness, and bowel sounds are hyperactive. Stool testing is negative for C difficile toxin, and stool culture yields no bacteria. Sigmoidoscopy reveals colonic ulcers with undermining edges that contain trophozoites. The causative organism for this patient's current condition can also produce which of the following manifestations?

Question

A 24-year-old man comes to the emergency department due to bloody diarrhea.  His symptoms began 10 days ago with episodic abdominal discomfort and loose stools.  The symptoms have progressively worsened, and he has had 6-8 stools mixed with blood and mucus over the past 2 days.  The patient recently returned from a 2-week trip to Egypt and felt well while traveling.  Temperature is 38 C (100.4 F), blood pressure is 120/70 mm Hg, and pulse is 86/min.  The abdomen is soft with mild tenderness on palpation of lower quadrants.  There is no guarding or rebound tenderness, and bowel sounds are hyperactive.  Stool testing is negative for C difficile toxin, and stool culture yields no bacteria.  Sigmoidoscopy reveals colonic ulcers with undermining edges that contain trophozoites.  The causative organism for this patient's current condition can also produce which of the following manifestations?

Quizplus · Accepted Answer

11ec160b_3809_a41f_9249_9d464039d8fe_MD0001_00 Entamoeba histolytica is an amoeba that infects the gastrointestinal tract of humans and is transmitted via the fecal-oral route when cysts are ingested from contaminated food or water. Cases are rare in the United States but commonly occur in developing regions where sanitation is poor. Most infected patients have no symptoms, but a minority (~10%) develop clinically significant colitis with subacute bloody-mucoid diarrhea, abdominal pain, and fever. The diagnosis is confirmed when cysts and trophozoites are seen on stool studies and/or colonic visualization demonstrates flask-shaped colonic ulcers (with trophozoites). Colonic E histolytica infections occasionally (~1%) spread through the bloodstream to the liver, lungs, and/or brain. The most common extraintestinal manifestation is a single amebic liver abscess in the right lobe of the liver. Invasive strains are more likely to have amebic proteases that degrade host extracellular membranes and secretory IgA. Almost all invasive strains also demonstrate contact-dependent cytotoxicity, whereby an amebic lectin binds the host cell, introduces an amebic porin into the host cell membrane, and causes cell lysis. (Choice A) Liver flukes (eg, Clonorchis, Opisthorchis) are typically transmitted due to consuming contaminated fish. The pathogen can remain in the bile duct of an infected patient for decades. Many cases are asymptomatic, but complications such as bile duct obstruction can occur. (Choice B) Ingestion of the egg stage of the pork tapeworm Taenia solium leads to neurocysticercosis, which is characterized by the formation of cystic brain lesions. Manifestations often occur years later and include seizures (primarily) and focal neurologic signs. Spread of E histolytic to the brain would cause an abscess, not a cyst. (Choice C) Schistosomiasis is parasitic blood fluke infection that is acquired when bathing or swimming in freshwater that contains the intermediate host, a freshwater snail. Most cases are asymptomatic but urinary shedding of eggs through the bladder can result in granulomatous inflammation, ulcerations, and, ultimately, bladder cancer. (Choice D) Cutaneous larva migrans is a hookworm infection that causes an intensely itchy, reddish-brown, migrating, serpiginous cutaneous track in the area near penetration (usually the lower extremities). Educational objective: Entamoeba histolytica is an amoeba that causes colitis characterized by ulcers with undermining edges (ie, flask-shaped) that may contain cysts and trophozoites. Trophozoites can occasionally (~1%) invade the colonic wall and disseminate through the blood to the liver, brain, or lungs. Amebic hepatic abscess is the most common extraintestinal manifestation.

A 24-Year-Old Man Comes to the Emergency Department Due to Bloody