Mycology Mcqs Remain

15 clinical MCQs in Medical Mycology. Amphotericin B would be used to treat all of the following EXCEPT:

Questions, Answers & Explanations

1. Q1. Amphotericin B would be used to treat all of the following EXCEPT:

   • Blastomycosis
   • Histoplasmosis
   • Aspergillosis
   • Ergotism

   Answer: Ergotism

   Explanation: Ergotism is caused by ingesting ergot alkaloids from Claviceps purpurea — it is a toxin poisoning, NOT a fungal infection. Amphotericin B treats fungal infections only.

2. Q2. All of the following are superficial mycoses EXCEPT:

   • Tinea pedis
   • Tinea nigra
   • Black piedra
   • Tinea versicolor

   Answer: Tinea pedis

   Explanation: Tinea pedis (athlete's foot) is a cutaneous mycosis, not superficial. Superficial mycoses affect only the outermost skin layer with no tissue invasion.

3. Q3. Which of the following statements regarding Tinea nigra is NOT correct?

   • Most prevalent in tropical and subtropical regions
   • Pigmented macules appear on palm and soles
   • It is difficult to isolate by microscopic examination from skin scrapings
   • Usually related to poor hygiene

   Answer: It is difficult to isolate by microscopic examination from skin scrapings

   Explanation: Tinea nigra is actually EASILY identified microscopically — skin scrapings show septate hyphae and budding yeast cells. It is caused by Hortaea werneckii.

4. Q4. Which of the following is the common cause of Athlete's foot?

   • Wearing tight shoes
   • Sweating a lot
   • Keeping feet wet for long periods
   • All of the above

   Answer: All of the above

   Explanation: All three create the warm, moist environment that Trichophyton rubrum and T. mentagrophytes thrive in — the main causes of tinea pedis.

5. Q5. All of the following are characteristics of cutaneous mycoses EXCEPT:

   • Infection of hair, skin and nails
   • The common cause of ringworm in humans only
   • Candida spp is associated with the infection
   • The keratinized layer of skin is prone to infection

   Answer: The common cause of ringworm in humans only

   Explanation: Dermatophytes cause ringworm in both humans AND animals (zoophilic species like M. canis from cats/dogs). Not limited to humans only.

6. Q6. All of the following dermatophytes are responsible for nail infections EXCEPT:

   • Epidermophyton floccosum
   • Trichophyton rubrum
   • Trichophyton mentagrophytes
   • Microsporum canis

   Answer: Microsporum canis

   Explanation: Microsporum canis primarily infects hair and skin but does NOT typically cause nail infections (onychomycosis). The other three commonly cause nail infections.

7. Q7. Which of the following is an opportunistic pathogenic fungus in humans?

   • Blastomyces dermatitidis
   • Coccidioides immitis
   • Candida albicans
   • Histoplasma capsulatum

   Answer: Candida albicans

   Explanation: Candida albicans is normal flora that becomes pathogenic when immunity is compromised. The others are TRUE pathogens that can infect immunocompetent hosts.

8. Q8. Aspergillosis is recognized in tissue by the presence of:

   • Metachromatic granules
   • Pseudohyphae
   • Budding cells
   • Septate hyphae

   Answer: Septate hyphae

   Explanation: Aspergillus shows characteristic septate hyphae with parallel walls and acute angle (45°) branching in tissue. NOT pseudohyphae (that's Candida).

9. Q9. Fungi often colonize lesions caused by other agents. Which is LEAST likely to be present as a colonizer?

   • Candida
   • Sporothrix
   • Mucor
   • Aspergillus

   Answer: Sporothrix

   Explanation: Sporothrix schenckii is a primary pathogen causing sporotrichosis through traumatic implantation — it does NOT typically colonize pre-existing lesions. Candida, Mucor and Aspergillus are known colonizers.

10. Q10. Which statement regarding dermatophytosis is correct?

    • Chronic infections are associated with zoophilic dermatophytes such as Microsporum canis
    • Chronic infections are associated with anthropophilic dermatophytes such as M. canis
    • Acute infections are associated with zoophilic dermatophytes such as M. canis
    • Acute infections are associated with anthropophilic dermatophytes such as M. canis

    Answer: Acute infections are associated with zoophilic dermatophytes such as M. canis

    Explanation: Zoophilic dermatophytes (from animals) cause ACUTE, highly inflammatory infections in humans because humans are not their natural host. Anthropophilic ones cause chronic, mild infections.

11. Q11. Which statement regarding laboratory identification of fungi is correct?

    • Histoplasma capsulatum requires less than 48 hours incubation for positive cultures
    • Since many nonpathogenic molds resemble dimorphic mycotic agents at 30°C, putative dimorphic pathogenic fungi must be confirmed by conversion to tissue form or DNA analysis
    • Molds are routinely speciated by physiologic tests such as sugar assimilation
    • A positive germ tube test provides rapid presumptive identification of Candida glabrata

    Answer: Since many nonpathogenic molds resemble dimorphic mycotic agents at 30°C, putative dimorphic pathogenic fungi must be confirmed by conversion to tissue form or DNA analysis

    Explanation: Histoplasma takes weeks to grow. Germ tube test identifies C. albicans NOT C. glabrata. Molds are identified morphologically not by sugar assimilation. Confirmation of dimorphic fungi requires tissue form conversion.

12. Q12. All of the following are examples of superficial mycoses EXCEPT:

    • Tinea nigra
    • Tinea versicolor
    • Tinea imbricate
    • White piedra

    Answer: Tinea imbricate

    Explanation: Tinea imbricate (caused by T. concentricum) is a CUTANEOUS mycosis involving deeper skin layers — not superficial. The others affect only the outermost skin surface.

13. Q13. Which of the following is NOT a characteristic of histoplasmosis?

    • Person to person transmission
    • Specific geographic distribution
    • Yeasts in tissue
    • Mycelial phase in the soil

    Answer: Person to person transmission

    Explanation: Histoplasmosis is NOT transmitted person to person. Infection occurs by inhaling spores from soil contaminated with bird/bat droppings. Endemic to Mississippi/Ohio River valleys.

14. Q14. You have made a clinical diagnosis of meningitis in a 50-year-old immunocompromised woman. A latex agglutination test on spinal fluid for capsular polysaccharide antigen is positive. Which is the most likely cause?

    • Candida albicans
    • Cryptococcus neoformans
    • Histoplasma capsulatum
    • Aspergillus fumigatus

    Answer: Cryptococcus neoformans

    Explanation: The latex agglutination test for CAPSULAR POLYSACCHARIDE antigen is the classic confirmatory test for Cryptococcus neoformans meningitis.

15. Q15. Compare Eumycetoma and Actinomycetoma — which is correct?

    • Eumycetoma is caused by true fungi; Actinomycetoma by bacteria like Nocardia
    • Both are caused by fungi
    • Actinomycetoma is more widespread than Eumycetoma
    • Both respond equally to antifungal treatment

    Answer: Eumycetoma is caused by true fungi; Actinomycetoma by bacteria like Nocardia

    Explanation: Eumycetoma = true fungal cause (e.g. Madurella). Actinomycetoma = caused by filamentous bacteria (Nocardia, Actinomyces). Important distinction — Actinomycetoma responds to antibiotics NOT antifungals.