📚 MEDICAL VIROLOGY & MYCOLOGY — MCQ BANK Mount Kenya University MBMM 3300 --- 🍄 SECTION 1: MYCOLOGY --- 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 patients acquired their infections in South America - C. Although infection is acquired by inhalation and initiated in the lungs, many patients develop cutaneous and mucocutaneous lesions - D. The vast majority of patients with active disease are males - E. The etiologic agent is inherently resistant to amphotericin B ✅ Answer: E — The etiologic agent is inherently resistant to amphotericin B Paracoccidioides brasiliensis is NOT resistant to amphotericin B. In fact, Amphotericin B is the drug of choice in severe cases. All other statements are true — it is dimorphic, endemic to South America, predominantly affects males, and spreads from lungs to skin/mucosa. --- MCQ 10 A kidney transplant patient develops nosocomial systemic candidiasis. The isolated Candida glabrata strain is resistant to fluconazole. What is the most reasonable oral alternative? - A. Flucytosine - B. Posaconazole - C. Griseofulvin - D. Amphotericin B - E. Clotrimazole ✅ Answer: B — Posaconazole Candida glabrata is notorious for developing azole resistance. Posaconazole is a broad-spectrum extended triazole effective against fluconazole-resistant strains and is available in oral form. Amphotericin B is effective but administered IV, not orally. Griseofulvin is only for dermatophytes. --- MCQ 11 All of the following are characteristics of systemic mycoses (deep mycoses) EXCEPT: - A. Most of the dimorphic fungi cause the infection - B. Pathogenesis mostly occurs due to the inhalation of spores - C. The most common body part is the lungs for ALL fungal infections - D. Aspergillosis and mucormycosis are systemic mycoses - E. Infection can develop in patients who are immunocompetent ✅ Answer: C — The lungs are the site for ALL fungal infections This is incorrect because not all systemic fungi enter through the lungs. For example: - Sporotrichosis → enters through skin trauma - Mycetoma → enters through skin penetration The statement is falsely absolute. All other options are valid characteristics of systemic mycoses. --- MCQ 12 Thousands of people in the western USA suddenly developed flu-like symptoms and pneumonia in 1992. The causative agent was found to be fungal spores in soil and air, causing fever, cough, and fatigue. The disease was termed Valley Fever. What is the pathogen? - A. Aspergillus niger - B. Paracoccidioides brasiliensis - C. Blastomyces dermatitidis - D. Coccidioides immitis - E. Tinea nigra ✅ Answer: D — Coccidioides immitis Valley Fever = Coccidioidomycosis , caused by Coccidioides immitis , endemic to the southwestern USA (San Joaquin Valley, Arizona, New Mexico). Inhaled arthrospores from dry, dusty soil cause acute pulmonary infection mimicking flu or pneumonia. --- MCQ 13 Which pathogen isolated from a sputum specimen shows mold growth with tuberculate macroconidia and oval microconidia in laboratory culture? - A. Histoplasma capsulatum - B. Coccidioides immitis