89 clinical MCQs in Medical Mycology. Organism without a known sexual stage would be classified in the: Fungi with no known tele. Kenya, Africa and glob...
Q1. Organism without a known sexual stage would be classified in the: Fungi with no known teleomorph (sexual stage) are classified as Fungi Imperfecti / Mitosporic fungi. ---
Answer: Mitosporic fungi
Q2. Antifungal drug such as inhibits proper formation of : Azoles like miconazole block ergosterol synthesis, disrupting plasma membrane formation. ---
Answer: Miconazole : a plasma membrane
Q3. Which fungus would you most likely find in pigeon droppings? Cryptococcus neoformans is enriched in soil contaminated with pigeon droppings. ---
Answer: Cryptococcus
Q4. Causes 200 million cases/year with itching sensation and burning internal pain: Vulvovaginal candidiasis is extremely common worldwide, causing itching and internal burning. ---
Answer: Vuvovaginitis
Q5. The formation of arthrospores and spherule is characteristic of: Coccidioides forms arthroconidia in soil/mold form and spherules in tissue. ---
Answer: Coccidioidomycoses
Q6. Aflatoxin is produced by and is : Aspergillus flavus produces aflatoxin, a potent hepatocarcinogen. ---
Answer: Aspergillus flavus ; carcinogen
Q7. Girl pricked finger pruning roses, pustule → ulcer → nodules along lymphatics. Most likely agent: Classic "rose gardener's disease" — lymphocutaneous sporotrichosis. ---
Answer: Sporothrix schenckii
Q8. Fungal cells that reproduce by budding are seen in tissues of patients with: Candida, Cryptococcus, and Sporothrix all appear as budding yeasts in tissue. ---
Answer: Candidiasis, cryptococcosis, and sporotrichosis
Q9. Which statement regarding paracoccidiomycosis is NOT correct? Paracoccidioides brasiliensis is susceptible to amphotericin B, not resistant. ---
Answer: The etiologic agent is inherently resistant to amphotericin B
Q10. Kidney transplant patient, nosocomial systemic candidiasis, Candida glabrata resistant to fluconazole — reasonable oral alternative: Posaconazole retains activity against fluconazole-resistant ---
Answer: Posaconazole
Q11. All are characteristics of systemic/deep mycosis EXCEPT: Not all systemic fungal infections start in the lungs (e.g., candidiasis can be catheter/GI-related). ---
Answer: The most common body part is the lungs for all fungal infections
Q12. Thousands in western USA, 1992, flu-like illness from inhaled soil fungal spores — "valley fever." Pathogen? Coccidioidomycosis = Valley Fever, endemic to the southwestern US. ---
Answer: Coccidioides immitis
Q13. Pathogen with mold growth showing tubercle macroconidia and oval microconidia in sputum culture: Tuberculate macroconidia are the classic identifying feature of Histoplasma capsulatum. ---
Answer: Histoplasma capsulatum
Q14. Which Trichosporon species causes scalp hair white piedra? T. ovoides is specifically associated with scalp/hair white piedra; T. inkin affects pubic hair. ---
Answer: Trichosporon ovoides
Q15. 26-year-old man, itchy white flaky stinging patches between toe webs/soles, inflammation, fissures. Likely agent: T. rubrum is the most common cause of chronic interdigital tinea pedis. ---
Answer: Trichophyton rubrum
Q16. Lesion characteristics of Pityriasis Versicolor: Malassezia-driven pityriasis versicolor causes irregular hypo-/hyperpigmented macules. ---
Answer: Hypopigmented and hyperpigmented irregular macules
Q17. 2-year-old girl, rash with raised borders on face/arms, source = pet cat with same rash. Likely fungus: M. canis is the classic zoophilic dermatophyte transmitted from cats. ---
Answer: Microsporum canis
Q18. Most correct statement about Deuteromycetes (fungi imperfecti): By definition, Deuteromycetes have no known/observed sexual stage. --- ## Set 2 — MBMM 3300, Exam Paper (Section A, Q19–35, mycology portion) ---
Answer: The sexual reproduction method is not clearly known
Q19. Which one of the following statements about fungi is NOT true? Fungi are heterotrophic and never photosynthetic (they lack chlorophyll). ---
Answer: Some fungi are photosynthetic
Q20. Most dimorphic pathogens are at °C and at °C: Mold form at ambient/room temp (~23°C), yeast form at body temp (~37°C). ---
Answer: Filamentous; 23; yeast forms; 37
Q21. A fungal mycelium may contain: Mycelia can have any of these features depending on the fungus. ---
Answer: All the above
Q22. All are examples of asexual spore formation EXCEPT: Basidiospores are sexual spores produced in a basidium. ---
Answer: Basidiospores
Q23. Fungal disease causing a blister-like lesion on the scalp: Dermatophyte infection of the scalp (tinea capitis) can present with vesicular/blister-like lesions. ---
Answer: Dermatophytosis
Q24. Amphotericin B would be used to treat all EXCEPT: Ergotism is caused by ergot alkaloid toxicity (Claviceps), not treated with antifungals. ---
Answer: Ergotism
Q25. A component of the cell membrane of most fungi is: Ergosterol is the fungal-membrane sterol analog to cholesterol in humans — the antifungal drug target. ---
Answer: Ergosterol
Q26. Physician in rural Latin American village: many mature males, few immature males/females affected. Diagnosis? Estrogen inhibits conversion of Paracoccidioides to its pathogenic yeast form, sparing females/prepubescent males. ---
Answer: Paracoccidioidomycosis
Q27. A fungus that can attack hair: Trichophyton and Microsporum both infect hair; Epidermophyton does not. ---
Answer: Trichophyton
Q28. Farmer in Mississippi, chronic cough, opaque mass on CXR, biopsy shows macrophages with multiple yeast forms. Likely diagnosis: Histoplasma capsulatum is endemic to the Ohio/Mississippi River valleys and lives intracellularly in macrophages. ---
Answer: Histoplasmosis
Q29. Which statement regarding fungal cell walls is correct? Cell-wall ligands mediate adhesion to host cells — a genuine virulence mechanism (note: polyenes/azoles target the membrane, not the wall, so d is wrong). ---
Answer: Ligands associated with cell walls of certain fungi mediate attachment to host cells
Q30. 54-year-old man, worsening headache, right arm weakness, brain abscess with darkly pigmented septate hyphae = phaeohyphomycosis. Genus? Cladophialophora bantiana is a classic neurotropic dematiaceous (pigmented) mold causing cerebral phaeohyphomycosis. ---
Answer: Cladophialophora
Q31. 35-year-old West African farmer, scaly papule → wart-like cauliflower lesions = chromoblastomycosis. Most correct statement: Sclerotic (Medlar) bodies divide by septation/fission — the diagnostic tissue form. ---
Answer: In tissue, organisms convert to spherical cells that reproduce by fission with transverse septations
Q32. 8-year-old boy, circular dry scaly pruritic leg lesion. Diagnostic significance of branching, septate, nonpigmented hyphae on KOH/calcofluor: Nonpigmented (hyaline) septate hyphae on skin scraping = classic dermatophyte infection. ---
Answer: Dermatophytosis
Q33. Which statement regarding epidemiology of candidiasis is correct? Oral thrush is extremely common in AIDS/immunosuppressed patients. ---
Answer: AIDS patients frequently develop mucocutaneous candidiasis, such as thrush
Q34. Which statement regarding dermatophytosis is correct? Zoophilic species (like M. canis) trigger a brisk host immune response → acute, inflammatory infection. ---
Answer: Acute infections associated with zoophilic dermatophytes (M. canis)
Q35. Which statement regarding lab identification of fungi is correct? Dimorphic pathogens must be confirmed (conversion, antigen, or molecular testing) since morphology alone is unreliable. --- ## Set 3 — Paper 2, 2017/2018 (MDBS3101), Q1–17 (mycology portion) ---
Answer: Since saprobic molds resemble dimorphic mycotic agents in culture at 30°C, identification must be confirmed by conversion to tissue form…
Q36. Which is an opportunistic pathogenic fungus in humans? Candida is part of normal flora and causes disease mainly in compromised hosts — the definition of opportunistic. ---
Answer: Candida albicans
Q37. Aspergillosis is recognized in tissue by the presence of: Aspergillus shows septate hyphae with acute-angle (45°) branching in tissue. ---
Answer: Septate hyphae
Q38. Fungi often colonize lesions due to other causes. Least likely colonizer: Sporothrix is a true pathogen causing primary infection, not typically a secondary colonizer. ---
Answer: Sporothrix
Q39. Girl pricked finger pruning roses; pustule → ulcer → nodules along lymphatics. Most likely agent: Classic sporotrichosis presentation ("rose gardener's disease"). ---
Answer: Sporothrix schenckii
Q40. Immunocompromised persons and fungal disease — least frequently associated: Malassezia causes superficial disease (tinea versicolor), not typically severe disease in immunocompromised hosts. ---
Answer: Malassezia furfur
Q41. Statements about Cryptococcus neoformans — all correct EXCEPT: Cryptococcus's main virulence factor is its polysaccharide capsule, not an exotoxin. ---
Answer: Pathogenesis is related primarily to production of exotoxin A
Q42. Fungal cells that reproduce by budding seen in tissues of: Same rationale as before — all three form budding yeasts in tissue. ---
Answer: Candidiasis, cryptococcosis, and sporotrichosis
Q43. NOT a characteristic of histoplasmosis: Histoplasmosis is acquired from environmental exposure (soil/bird-bat droppings), not person-to-person. ---
Answer: Person-to-person transmission
Q44. Natural habitat for Paracoccidioides brasiliensis: Soil, particularly in tropical/humid regions of Latin America. ---
Answer: Soil
Q45. Coccidioidomycosis is also called: Also known as "desert rheumatism." ---
Answer: Valley fever
Q46. Most common mycotoxin that infects nuts/grains, causing severe reactions: Aflatoxins contaminate peanuts/grains and are potent carcinogens. ---
Answer: Aflatoxins
Q47. Aflatoxins are produced by which fungus? ---
Answer: flavus
Q48. Coccidioides immitis exists as molds in soil and spherule in tissues — hence termed ---
Answer: Dimorphic
Q49. Aflatoxins are a serious problem because: (Note: d is also true, but "potent carcinogens" is the key reason they're a serious health hazard.) ---
Answer: They are potent carcinogens
Q50. More visible symptoms of fungal infection appearing recently because: --- ## Set 4 — "Medical Mycology CAT" (short quiz) ---
Answer: All the above
Q51. Most correct statement about hyphae: The septum is the separating wall (not "hyphae" — that's a mislabel in option c), and chitin is the defining polysaccharide of the fungal cell wall. ---
Answer: The cell wall consists of a polysaccharide called Chitin
Q52. pH range best for fungal culture media growth: Fungi generally prefer slightly acidic media (~pH 4–6, e.g., Sabouraud dextrose agar). ---
Answer: pH 4–6
Q53. Color of fungal cell wall when dyed with periodic acid–Schiff (PAS) stain: PAS stains fungal wall polysaccharides magenta/red. ---
Answer: Red
Q54. Fungi that produce poisonous mycotoxin called aflatoxin ---
Answer: A and B
Q55. Most correct about Deuteromycetes ---
Answer: B and C
Q56. All are superficial mycoses EXCEPT: Tinea imbricata is a cutaneous (not purely superficial) dermatophytosis. ---
Answer: Tinea imbricata
Q57. Which Trichosporon spp. causes scalp hair white piedra? ---
Answer: T. ovoides
Q58. Which does NOT have microconidia? Epidermophyton produces only macroconidia, no microconidia. ---
Answer: Epidermophyton
Q59. All dermatophytes responsible for nail infections EXCEPT: M. canis rarely causes onychomycosis (nail infection); it mainly affects hair/skin. ---
Answer: Microsporum canis
Q60. Responsible for mycosis of the foot mostly in the Indian subcontinent: Madurella mycetomatis is the leading cause of eumycetoma ("Madura foot") in South Asia. ---
Answer: Madurella mycetomatis
Q61. (continued options for mycetoma agents) Nocardia causes actinomycetoma (bacterial), distinct from the fungal (eumycetoma) agents. ---
Answer: Nocardia spp
Q62. Drug of choice for Sporotrichosis: Itraconazole is first-line for cutaneous/lymphocutaneous sporotrichosis. --- ## Set 5 — Large mycology exam (50 questions) ---
Answer: Itraconazole
Q63. A component of the cell membrane of most fungi is ---
Answer: Ergosterol
Q64. Rural Latin American village — many mature males, few immature males/females affected. Diagnosis? ---
Answer: Paracoccidioidomycosis
Q65. A fungus that can attack hair is ---
Answer: Trichophyton
Q66. Which statement regarding fungal cell walls is correct? ---
Answer: Ligands associated with cell walls mediate attachment to host cells
Q67. 54-year-old man, headache, arm weakness, brain abscess with pigmented septate hyphae = phaeohyphomycosis. Genus? ---
Answer: Cladophialophora
Q68. 35-year-old West African farmer — chromoblastomycosis. Most correct statement ---
Answer: In tissue, organisms convert to spherical cells that divide by fission with transverse septations
Q69. 8-year-old boy, dry scaly leg lesion; branching, septate, nonpigmented hyphae on KOH ---
Answer: Dermatophytosis
Q70. Epidemiology of candidiasis — correct statement ---
Answer: AIDS patients frequently develop mucocutaneous candidiasis (thrush)
Q71. Dermatophytosis — correct statement ---
Answer: Acute infections associated with zoophilic dermatophytes (M. canis)
Q72. Lab identification of fungi — correct statement ---
Answer: Saprobic molds resemble dimorphic agents at 30°C, so identification of putative dimorphic pathogens must be confirmed by conversion to…
Q73. Which statement about phaeohyphomycosis is correct? Dematiaceous (pigmented) fungi causing phaeohyphomycosis can produce a spectrum from localized sinusitis to subcutaneous cysts to disseminated disease. ---
Answer: Phaeohyphomycosis may exhibit subcutaneous or systemic disease, as well as sinusitis
Q74. Which statement regarding aspergillosis is correct? Aspergillus causes a wide range of local infections (otomycosis, keratitis, onychomycosis, sinusitis) beyond invasive pulmonary disease; blood cultures are usually negative even in invasive disease, so c is false. ---
Answer: Clinical manifestations include local infections of the ear, cornea, nails, and sinuses
Q75. Which statement regarding sporotrichosis is correct? Sporothrix schenckii is thermally dimorphic (mold in environment, yeast in tissue at 37°C); most cases occur in immunocompetent gardeners/farmers and do spread along lymphatics. ---
Answer: The etiologic agent is a dimorphic fungus
Q76. Which statement about blastomycosis is correct? Broad-based budding is the hallmark microscopic feature of Blastomyces dermatitidis in tissue. ---
Answer: In tissue, one finds large, thick-walled, single budding yeast cells with broad connections between parent yeast and bud
Q77. Which statement regarding paracoccidiomycosis is NOT correct? Paracoccidioides is susceptible to amphotericin B — it is not inherently resistant. ---
Answer: The etiologic agent is inherently resistant to amphotericin B
Q78. Kidney transplant patient, nosocomial systemic candidiasis, Candida glabrata resistant to fluconazole — reasonable oral alternative: Posaconazole is active against fluconazole-resistant ---
Answer: Posaconazole
Q79. Which antifungal drug does NOT target biosynthesis of ergosterol in the fungal membrane? Micafungin is an echinocandin — it targets the cell wall (β-glucan synthase), not the ergosterol pathway. ---
Answer: Micafungin
Q80. Which pathogenic yeast is NOT a common member of normal human flora/microbiota? Cryptococcus neoformans is acquired from the environment (soil, pigeon droppings), unlike Candida/Malassezia which are commensals. ---
Answer: Cryptococcus neoformans
Q81. All are examples of superficial mycoses EXCEPT: Tinea pedis is a cutaneous dermatophytosis, invading keratin of skin — deeper than the truly superficial (stratum corneum surface only) infections. ---
Answer: Tinea pedis
Q82. Which statement about Tinea nigra infections is NOT correct? Tinea nigra (Hortaea werneckii) is actually easy to identify microscopically — pigmented septate hyphae are readily visible on KOH prep. ---
Answer: Difficult to isolate by microscopic examination of skin scrapings
Q83. Which Trichosporon species causes scalp hair white piedra? ---
Answer: T. ovoides
Q84. All are characteristics of cutaneous mycoses EXCEPT: Dermatophytes causing "ringworm" also infect animals (zoophilic species like M. canis) — not humans only. ---
Answer: Common cause of ringworm in humans only
Q85. 26-year-old man, itchy white flaky stinging patches between toe webs/soles with inflammation and fissures ---
Answer: Trichophyton rubrum
Q86. Common cause of Athlete's foot? All these conditions create a warm, moist environment favoring dermatophyte growth. ---
Answer: All of the above
Q87. 2-year-old girl, rash with raised borders on face/arms; pet cat has same rash: M. canis is the classic zoophilic dermatophyte transmitted from cats. ---
Answer: Microsporum canis
Q88. All are zoophilic dermatophytes — select all that apply: All four are animal-associated (zoophilic) dermatophyte species. ---
Answer: Microsporum canis
Q89. Most reliable lab method for isolation of Trichophyton rubrum? Direct KOH microscopy plus culture of skin scrapings is the gold-standard diagnostic approach for dermatophytes. ---
Answer: Skin scrapings, microscopic examination using KOH