WBR233
| 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::Dermatology |
| Prompt | [[Prompt::A 20-year-old man presents to the physician’s office with complaints of several skin lesions for the past 2 days. He recently arrived to the United States from Iraq. In the clinic, the patient's temperature is 36.8 °C (98.2 °F), his blood pressure is 120/78 mmHg, his heart rate is 68/min, and his respiratory rate is 14/min. On physical examination, the patient has red cutaneous nodules and skin ulcers as shown in the figure below. Skin scraping with microscopic analysis and needle aspiration of the tissue fluid from the margin were performed. Which of the following organisms is most likely responsible for this patient’s condition?
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| Answer A | AnswerA::''Toxoplasma gondii'' |
| Answer A Explanation | [[AnswerAExp::Toxoplasma gondii is a parasitic infection that is clinically relevant in utero and among HIV-positive patients. Transmission of T. gondii cysts is usually via ingestion of cysts found in contaminated meat and cat feces. Skin lesions are not characteristic findings of toxoplasmosis.]] |
| Answer B | AnswerB::''Trypanosoma brucei'' |
| Answer B Explanation | [[AnswerBExp::Trypanosoma brucei is the causative agent of African sleeping sickness, transmitted by the Tse Tse fly. The disease is characterized by somnolence, lymphadenopathy and recurrent fevers. Winterbottom’s sign is typically observed among patients with early trypanosomiasis and is characterized by swollen lymph in the posterior cervical region.]] |
| Answer C | AnswerC::''Leishmania aethiopica'' |
| Answer C Explanation | AnswerCExp::Diagnosis of cutaneous leishmaniasis is based on physical examination findings of characteristic non-healing scaling lesions that frequently ulcerate. |
| Answer D | AnswerD::''Loa loa'' |
| Answer D Explanation | [[AnswerDExp::Loa loa (eye worm) is a nematode that rests in the subcutaneous layer of the skin. Before transmission to the human host, Loa loa larvae grow in horseflies, such as deer flies and yellow flies.]] |
| Answer E | AnswerE::''Paragonimus westermani'' |
| Answer E Explanation | [[AnswerEExp::Paragonimus westermani (lung fluke) is a trematode that is contaminates undercooked crab meat. It often causes either a subacute or a chronic lung disease and hemoptysis. Disseminated disease can spread to the spinal cord and may result in paralysis.]] |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Leishmaniasis has a spectrum of cutaneous, mucocutaneous, and visceral manifestations. Cutaneous leishmaniasis is a parasitic disease that is characterized by multiple skin ulcerations. The disease is spread by the bite of sand flies. Diagnosis of cutaneous leishmaniasis is based on physical examination findings of characteristic non-healing scaling lesions that frequently ulcerate. The disease is endemic to several regions of the world, most commonly the Middle East region in Afghanistan, Algeria, Iran, Iraq, Saudi Arabia, and Syria and in the South American region in Brazil and Peru. Treatment of cutaneous leishmaniasis is pentavalent antimonials, such as sodium stibogluconate (Pentostam) and local care of ulcerating lesions that may be exposed to bacterial super-infections, commonly Staphylococcus aureus. Educational Objective: Cutaneous leishmaniasis is a common form of leishmaniasis characterized by ulcerating red lesions. Leishmaniasis is endemic to the Middle East and South America. The causative organism is the Leishmania parasite. Sodium stibogluconate is an effective treatment for cutaneous leishmaniasis. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Microbiology, WBRKeyword::Parasites, WBRKeyword::Skin ulcer, WBRKeyword::Skin lesion, WBRKeyword::Zoonotic infection, WBRKeyword::Leishmania aethiopica, WBRKeyword::Cutaneous leishmaniasis, WBRKeyword::Leishmaniasis |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
