MCQ 1 An organism without a known sexual stage of repr
📚 MEDICAL VIROLOGY & MYCOLOGY — MCQ BANK Mount Kenya University MBMM 3300 --- 🍄 SECTION 1: MYCOLOGY --- MCQ 1 An organism without a known sexual stage of reproduction would be classified in which of the following fungal groups? A. Zygomycota B. Mitosporic fungi C. Ascomycota D. Basidiomycota E. Chytridiomycota ✅ Answer: B — Mitosporic fungi Fungi with no known sexual stage are classified as Fungi Imperfecti (Deuteromycota/Mitosporic fungi). They reproduce exclusively through asexual means via mitosis, producing conidia. Examples include Candida and Aspergillus species in their imperfect forms. --- MCQ 2 An antifungal drug such as Miconazole inhibits proper formation of which cellular component? A. Nystatin inhibits cell wall formation B. Miconazole inhibits plasma membrane formation C. Griseofulvin inhibits DNA synthesis D. Flucytosine inhibits microtubule formation E. Amphotericin B inhibits protein synthesis ✅ Answer: B — Miconazole inhibits the plasma membrane Miconazole is an azole antifungal that inhibits the enzyme lanosterol 14-α-demethylase , blocking ergosterol biosynthesis and disrupting the fungal plasma membrane. Key comparison: Amphotericin B → binds ergosterol directly Griseofulvin → disrupts microtubules Flucytosine → inhibits DNA/RNA synthesis Nystatin → binds ergosterol (polyene) --- MCQ 3 Which of the following fungi would you most likely find growing in pigeon droppings? A. Trichophyton B. Pneumocystis C. Cryptococcus D. Coccidioides E. Sporothrix ✅ Answer: C — Cryptococcus Cryptococcus neoformans thrives in soil enriched by pigeon and bird droppings . The nitrogen-rich guano provides ideal growth conditions. Inhalation of dried droppings is the primary route of human infection, potentially causing meningitis especially in immunocompromised individuals. --- MCQ 4 Which fungal condition causes more than 200 million cases per year worldwide, with symptoms including an itching sensation and burning internal pain? A. Onychomycosis B. Thrush C. Tinea cruris (Jock itch) D. Vulvovaginitis E. Sporotrichosis ✅ Answer: D — Vulvovaginitis Vulvovaginal candidiasis caused by Candida albicans is among the most common fungal infections globally. Symptoms include vaginal itching, burning, and discharge. Risk factors include antibiotic use, pregnancy, diabetes, and immunosuppression. --- MCQ 5 The formation of arthrospores and spherules in infected tissue is characteristic of which fungal disease? A. Coccidioidomycosis B. Histoplasmosis C. Candidiasis D. Aspergillosis E. Blastomycosis ✅ Answer: A — Coccidioidomycosis Coccidioides immitis uniquely produces: Arthrospores → barrel-shaped spores in soil (mold form, 25°C) Spherules → large round structures filled with endospores in tissue (37°C) This dimorphic characteristic is pathognomonic for Coccidioidomycosis (Valley Fever). --- MCQ 6 Aflatoxin is produced by which organism, and what type of substance is it? A. Sporothrix schenkii — Hallucinogen B. Aspergillus flavus — Carcinogen C. Claviceps purpurea — Hallucinogen D. Aspergillus niger — Mycotoxin E. Aspergillus fumigatus — Carcinogen ✅ Answer: B — Aspergillus flavus; Carcinogen Aflatoxin is produced by Aspergillus flavus and A. parasiticus . It is a potent hepatocarcinogen that contaminates peanuts, corn, and stored grains. It is one of the most carcinogenic naturally occurring substances known. Note: Claviceps purpurea produces ergot alkaloids which are hallucinogenic. --- MCQ 7 A girl who pricked her finger while pruning rose bushes develops a local pustule that progresses to an ulcer. Several nodules then develop along the local lymphatic drainage. What is the most likely causative agent? A. Aspergillus fumigatus B. Sporothrix schenckii C. Cryptococcus neoformans D. Candida albicans E. Coccidioides immitis ✅ Answer: B — Sporothrix schenckii This is the classic presentation of Sporotrichosis — also called "Rose Gardener's Disease." The dimorphic fungus Sporothrix schenckii lives on plants and soil. A thorn prick inoculates the fungus, causing a local lesion that spreads in a characteristic lymphocutaneous pattern — ascending nodules along lymphatic channels. --- MCQ 8 Fungal cells that reproduce by budding are seen in the infected tissues of patients with which of the following combinations? A. Candidiasis, cryptococcosis, and sporotrichosis B. Mycetoma, candidiasis, and mucormycosis C. Tinea corporis, tinea unguium, and tinea versicolor D. Sporotrichosis, mycetoma, and aspergillosis E. Histoplasmosis, candidiasis, and sporotrichosis ✅ Answer: A — Candidiasis, cryptococcosis, and sporotrichosis All three pathogens exist as budding yeast forms in host tissue: Candida → oval budding yeast + pseudohyphae Cryptococcus → encapsulated budding yeast Sporothrix → cigar-shaped budding yeast in tissue This is their parasitic (tissue) phase morphology at 37°C. --- MCQ 9 Which of the following statements regarding paracoccidioidomycosis is NOT correct? A. The etiologic agent is a dimorphic fungus B. Most patien