Dimorphic fungi Practice Questions

Question 1

A 34-year-old woman presents with multiple round, scaly patches on her chest and back. The lesions are hypopigmented and slightly pruritic. KOH preparation of skin scrapings shows short, angular hyphae. Which of the following best describes the causative organism's morphology in culture?

Accepted Answer

Branching, septate hyphae with characteristic 'spaghetti and meatballs' appearance

Answer

Non-septate hyphae with sporangiospores

Answer

Branching, septate hyphae with tear-drop microconidia

Answer

Pseudohyphae with blastoconidia

Question 2

A 44-year-old man comes to the physician because of a 3-week history of productive cough, fever, and lethargy. He also has several skin lesions over his body. His symptoms began 3 weeks after he returned from a camping trip in Kentucky. Three years ago, he underwent kidney transplantation for polycystic kidney disease. Current medications include sirolimus and prednisone. His temperature is 38°C (100.4°F). Diffuse crackles are heard over the lung fields. There are 4 white, verrucous skin patches over his chest and upper limbs. A photomicrograph of a skin biopsy specimen from one of the lesions is shown. Which of the following is the most likely diagnosis?

Accepted Answer

Blastomycosis

Answer

Coccidioidomycosis

Answer

Mucormycosis

Answer

Cryptococcosis

Answer

Histoplasmosis

Question 3

A young woman from the Ohio River Valley in the United States currently on corticosteroid therapy for ulcerative colitis presented to a clinic complaining of fever, sweat, headache, nonproductive cough, malaise, and general weakness. A chest radiograph revealed patchy pneumonia in the lower lung fields, together with enlarged mediastinal and hilar lymph nodes. Skin changes suggestive of erythema nodosum (i.e. an acute erythematous eruption) were noted. Because the patient was from a region endemic for fungal infections associated with her symptoms and the patient was in close contact with a person presenting similar symptoms, the attending physician suspected that systemic fungal infection might be responsible for this woman’s illness. Which of the following laboratory tests can the physician use to ensure early detection of the disease, and also effectively monitor the treatment response?

Accepted Answer

Antigen detection

Answer

Skin tests

Answer

Fungal staining

Answer

Culture method

Answer

Antibody testing

Question 4

A 52-year-old man comes to the physician because of a 4-day history of a productive cough, shortness of breath, and low-grade fever. He works as a farmer in southern Arizona. Physical examination shows multiple skin lesions with a dark blue center, pale intermediate zone, and red peripheral rim on the upper and lower extremities. There are diffuse crackles on the left side of the chest. An x-ray of the chest shows left basilar consolidation and left hilar lymphadenopathy. A photomicrograph of tissue obtained from a biopsy of the lung is shown. Which of the following is the most likely causal pathogen?

Accepted Answer

Coccidioides immitis

Answer

Paracoccidioides brasiliensis

Answer

Candida albicans

Answer

Blastomyces dermatitidis

Answer

Aspergillus fumigatus

Question 5

An investigator is studying growth patterns of various fungal pathogens. Incubation of an isolated fungus at 25°C shows branching hyphae with rosettes of conidia under light microscopy. After incubation at 37°C, microscopic examination of the same organism instead shows smooth, white colonies with rounded, elongated cells. Infection with the investigated pathogen is most likely to cause which of the following conditions?

Accepted Answer

Sporotrichosis

Answer

Pityriasis versicolor

Answer

Candidiasis

Answer

Cryptococcosis

Answer

Coccidioidomycosis

Question 6

A 73-year-old man presents to the office, complaining of “weird blisters” on his right hand, which appeared 2 weeks ago. The patient says that he initially had a rash, which progressed to blisters. He denies any trauma or known contact with sick people. He is worried because he hasn’t been able to garden since the rash appeared, and he was planning on entering his roses into an annual competition this month. His vital signs are stable. On physical exam, the patient has multiple bullae accompanied by red, papular lesions on his right hand, which progress to his forearm. The right axillary lymph nodes are swollen and tender. What is the treatment for the most likely diagnosis of this patient?

Accepted Answer

Itraconazole

Answer

Azithromycin

Answer

Topical corticosteroids

Answer

Doxycycline

Answer

Potassium iodide solution

Question 7

A 19-year-old woman comes to the physician because of worsening pain with swallowing for 3 days and a dry sensation in the mouth over the past week. She has a history of asthma controlled with inhaled fluticasone and albuterol. Physical examination shows white plaques on the dorsal surface of the tongue and buccal mucosa that bleed when scraped off. Which of the following is the most appropriate pharmacotherapy?

Accepted Answer

Nystatin

Answer

Amphotericin B

Answer

Acyclovir

Answer

Griseofulvin

Answer

Triamcinolone

Question 8

A 40-year-old farmer from Ohio seeks evaluation at a clinic with complaints of a chronic cough, fevers, and anorexia of several months duration. On examination, he has generalized lymphadenopathy with hepatosplenomegaly. A chest radiograph reveals local infiltrates and patchy opacities involving all lung fields. Fine needle aspiration of an enlarged lymph node shows the presence of intracellular yeast. A fungal culture shows the presence of smooth, thin-walled microconidia and tuberculate macroconidia. Which of the following is the most likely diagnosis?

Accepted Answer

Histoplasmosis

Answer

Coccidioidomycosis

Answer

Blastomycosis

Answer

Cryptococcosis

Answer

Sporotrichosis

Question 9

A 16-year-old boy presents to his pediatrician because he has noticed white plaques forming on his tongue over the last 5 days. He recently returned from a boy scout trip where he traveled across the country and hiked through the woods. His past medical history is significant for asthma for which he uses an inhaler as needed. He says that during the trip he felt short of breath several times and had to use the inhaler. He also says that several of his friends appeared to get sick on the same trip and were coughing a lot. He has not experienced any other symptoms since returning from the trip. On presentation, he is found to have white plaques on the tongue that can be scraped off. Which of the following is a characteristic of the most likely cause of this patient's disease?

Accepted Answer

Germ tube formation

Answer

Acute angle branching

Answer

Spherules containing endospores

Answer

Latex agglutination

Answer

Broad-based budding

Question 10

A 50-year-old HIV-positive male presents to the ER with a two-day history of fever and hemoptysis. Chest radiograph shows a fibrocavitary lesion in the right middle lobe. Biopsy of the afflicted area demonstrates septate hyphae that branch at acute angles. Which of the following is the most likely causal organism?

Accepted Answer

Aspergillus fumigatus

Answer

Mycobacterium tuberculosis

Answer

Pneumocystis jirovecii

Answer

Candida albicans

Answer

Mucor species

Dimorphic fungi

Study Resources

Lessons

Questions

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Lessons

Blastomyces dermatitidis

Coccidioides immitis/posadasii

Paracoccidioides brasiliensis

Sporothrix schenckii complex

Talaromyces (Penicillium) marneffei

Dimorphic fungi characteristics

Geographic distribution of dimorphic fungi

Clinical presentations of dimorphic fungal infections

Diagnostic approaches for dimorphic fungi

Treatment of dimorphic fungal infections

Host factors in dimorphic fungal infections

Environmental sources and prevention

Practice Questions

Flashcards

About Dimorphic fungi for USMLE

Lessons in Dimorphic fungi

Master Dimorphic fungi