Systemic & Opportunistic Mycoses MCQ Quiz | Mycology

1. Which dimorphic fungus, found in soil enriched with bird or bat droppings, typically presents as intracellular yeasts within macrophages?

2. A 45-year-old farmer from the Mississippi River valley presents with chronic pneumonia and verrucous skin lesions. A biopsy reveals large, thick-walled yeasts with a single, broad-based bud. What is the most likely causative agent?

3. A patient returning from a trip to Arizona develops fever, cough, and arthralgias. A lung biopsy shows large spherules containing endospores. This presentation is characteristic of which fungal infection?

4. Microscopic examination of a sample from a patient with oral and nasal mucosal ulcers reveals a large yeast cell with multiple buds, resembling a “mariner’s wheel”. This is pathognomonic for:

5. A positive germ tube test, where a yeast cell forms a short, non-septate hyphal extension in serum at 37°C, is a rapid presumptive identification method for which species?

6. An HIV-positive patient presents with headache and fever. A CSF sample is stained with India ink, revealing encapsulated yeasts. What is the most probable diagnosis?

7. A patient with a history of tuberculosis has a chest X-ray showing a “fungus ball” within a pre-existing lung cavity. This aspergilloma is most commonly caused by:

8. A diabetic patient in ketoacidosis develops a rapidly progressing facial swelling and black necrotic eschar in the nasal cavity. A biopsy would likely show:

9. A patient with AIDS presents with dyspnea and a non-productive cough. A bronchoalveolar lavage specimen stained with Gomori methenamine silver (GMS) reveals cyst-like structures. The causative agent is:

10. Sabouraud Dextrose Agar (SDA) is the standard culture medium for most fungi primarily because:

11. “Darling’s disease,” often asymptomatic or presenting as a self-limiting flu-like illness, is another name for infection caused by:

12. The characteristic microscopic feature of *Blastomyces dermatitidis* in tissue is a yeast cell that is:

13. “Valley Fever” is an endemic mycosis primarily found in which geographical region?

14. Which of the following is considered a primary systemic pathogen, capable of causing disease in immunocompetent hosts, rather than an opportunist?

15. The major sterol component of the fungal cell membrane, which is a primary target for azole and polyene antifungal drugs, is:

16. In tissue, *Aspergillus fumigatus* appears as:

17. Which host factor is most strongly associated with rhinocerebral mucormycosis?

18. The primary virulence factor of *Cryptococcus neoformans*, which helps it evade phagocytosis, is its:

19. In tissue, *Candida albicans* can be seen in three forms: yeast, pseudohyphae, and true hyphae. The presence of pseudohyphae and hyphae typically indicates:

20. Although historically classified as a protozoan, *Pneumocystis jirovecii* is now known to be a fungus based on:

21. Which fluorescent stain binds to chitin in fungal cell walls, causing them to fluoresce brightly under a UV microscope, and is often used for rapid screening of clinical specimens?

22. The ability of systemic fungi like *Histoplasma* and *Blastomyces* to exist as mold in the environment (25-30°C) and as yeast in the host (37°C) is known as:

23. The most common cause of fungal bloodstream infections (candidemia) in hospitalized patients is:

24. South American blastomycosis is the common name for the disease caused by which fungus, which is largely restricted to Central and South America?

25. Which term best describes the hyphae of fungi belonging to the class Zygomycetes, such as *Rhizopus* and *Mucor*?