Fungal Infections Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Fungal Infections. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Fungal Infections Indian Medical PG Question 1: A man has undergone renal transplant and is taking immunosuppressant drug. On biopsy there was presence of budding cells with pseudohyphae. Identify the organism?
- A. Invasive candidiasis (Correct Answer)
- B. Pneumocystis
- C. Invasive aspergillosis
- D. Histoplasmosis
Fungal Infections Explanation: ***Invasive candidiasis***
- The presence of **budding cells** and **pseudohyphae** on biopsy is a classic histological finding for *Candida* species.
- Individuals who have undergone **renal transplant** and are on **immunosuppressant drugs** are at high risk for opportunistic fungal infections, including invasive candidiasis.
*Pneumocystis*
- *Pneumocystis jirovecii* typically causes pneumonia and is characterized by cysts or trophic forms in lung tissue, not budding cells and pseudohyphae.
- While common in immunocompromised patients, its microscopic morphology is distinctly different from *Candida*.
*Invasive aspergillosis*
- *Aspergillus* species are characterized by **septate hyphae with acute angle branching** (typically 45-degree angles) on microscopy.
- They do not form budding cells or pseudohyphae, which are characteristic of *Candida*.
*Histoplasmosis*
- *Histoplasma capsulatum* appears as **small, oval-shaped yeast cells** (2-4 µm) often found within macrophages.
- It does not form pseudohyphae or large budding cells as described in the question.
Fungal Infections Indian Medical PG Question 2: Amphotericin B acts on:-
- A. Cell membrane (Correct Answer)
- B. Cytoplasm
- C. Nucleus
- D. Cell wall
Fungal Infections Explanation: ***Cell membrane*** Amphotericin B primarily targets the **ergosterol** in the fungal **cell membrane** [1]. It binds to **ergosterol**, forming pores and disrupting the membrane's integrity, leading to leakage of cellular contents and ultimately cell death [1]. *Cytoplasm* The cytoplasm is the internal fluid of the cell where many metabolic processes occur, but it is **not the primary target** of amphotericin B's fungicidal action. While cytoplasmic contents leak out due to membrane damage, the drug does not directly act on cytoplasmic components to exert its effect. *Nucleus* The nucleus contains the genetic material of the fungal cell, but amphotericin B does **not directly interact with nuclear components** or DNA. Damage to the cell membrane is the primary mechanism, with nuclear function only indirectly affected by overall cellular disruption. *Cell wall* Fungal cell walls are composed of **chitin and glucans**, but amphotericin B **does not target these components**. Its action is distinct from drugs that inhibit cell wall synthesis, such as echinocandins.
Fungal Infections Indian Medical PG Question 3: Histoplasma capsulatum, a dimorphic fungus found in soil heavily contaminated with bird droppings, is identified in tissue biopsies by which of the following characteristics?
- A. Yeasts with broad-based buds
- B. Single-cell yeasts with pseudohyphae
- C. Arthrospores
- D. Oval budding yeasts within macrophages (Correct Answer)
Fungal Infections Explanation: ***Oval budding yeasts within macrophages***
- In tissue biopsies, **Histoplasma capsulatum** characteristically appears as small, **oval-shaped budding yeasts** that are predominantly found **intracellularly within macrophages**.
- This intracellular location is a key diagnostic feature, as the organism can survive and multiply inside these phagocytic cells.
*Yeasts with broad-based buds*
- This description is characteristic of **Blastomyces dermatitidis**, another dimorphic fungus, which displays large yeasts with a single broad-based bud in tissue.
- Unlike *Histoplasma*, **Blastomyces** yeasts are typically much larger and not necessarily intracellular.
*Single-cell yeasts with pseudohyphae*
- This morphology is characteristic of **Candida albicans**, particularly in its pathogenic forms within tissues.
- **Candida** forms true hyphae and pseudohyphae, and its yeasts do not typically reside within macrophages in the same manner as *Histoplasma*.
*Arthrospores*
- **Arthrospores** (also called arthroconidia) are characteristic of fungi like **Coccidioides immitis**, which appear as barrel-shaped structures in laboratory cultures, but *spherules containing endospores* are seen in tissue.
- **Histoplasma** does not form arthrospores in human tissue; it forms yeasts.
Fungal Infections Indian Medical PG Question 4: Regarding fungal cell wall, all are true except:
- A. Contains chitin
- B. Prevent osmotic damage
- C. Does not contain peptidoglycan
- D. Azoles act on them (Correct Answer)
Fungal Infections Explanation: ***Azoles act on them***
- **Azole antifungals** primarily target the **ergosterol synthesis** pathway, specifically inhibiting the **lanosterol 14-alpha-demethylase** enzyme, which is located in the fungal cell membrane, not the cell wall.
- While the cell wall is crucial for fungal viability, agents targeting it (e.g., **echinocandins**) are distinct from azoles.
*Contains chitin*
- The fungal cell wall is indeed a complex structure composed of various carbohydrates, with **chitin** being a major structural polysaccharide that provides rigidity.
- Chitin is a **beta-(1,4)-linked polymer of N-acetylglucosamine** and is a unique component distinguishing fungal cells from animal cells.
*Prevent osmotic damage*
- The rigid fungal cell wall provides structural support and protects the cell from **environmental stresses**, particularly **osmotic lysis** in hypotonic environments.
- It maintains the cell's integrity against internal **turgor pressure**, which is essential for fungal growth and survival.
*Does not contain peptidoglycan*
- Fungal cell walls are distinct from bacterial cell walls in their composition; they **do not contain peptidoglycan**.
- **Peptidoglycan** is a characteristic component of bacterial cell walls, which is targeted by antibiotics like penicillins.
Fungal Infections Indian Medical PG Question 5: A biopsy of a lung nodule from a patient with a history of bird exposure reveals yeast cells with thick capsules. What is the most likely pathogen?
- A. Aspergillus fumigatus
- B. Blastomyces dermatitidis
- C. Histoplasma capsulatum
- D. Cryptococcus neoformans (Correct Answer)
Fungal Infections Explanation: ***Cryptococcus neoformans***
- The presence of **yeast cells with thick capsules** is a classic histological finding for *Cryptococcus neoformans*.
- While *Cryptococcus* commonly affects immunocompromised individuals, it can also be found in **bird droppings**, particularly from pigeons, making the history of bird exposure relevant.
*Aspergillus fumigatus*
- *Aspergillus fumigatus* typically presents as **hyphae**, not yeast cells, and would not have a thick capsule.
- Infections often manifest as **aspergillomas** (fungus balls) in lung cavities or invasive disease in immunocompromised patients.
*Blastomyces dermatitidis*
- *Blastomyces dermatitidis* appears as **large, broad-based budding yeast cells** but does not possess a thick capsule.
- It is typically found in the **soil**, especially in moist areas, and its association with bird exposure is not as strong as with *Cryptococcus*.
*Histoplasma capsulatum*
- *Histoplasma capsulatum* is characterized by **small intracellular yeast forms** within macrophages and does not have a thick capsule.
- It is strongly associated with **bird and bat droppings** but its microscopic appearance is distinct from that described.
Fungal Infections Indian Medical PG Question 6: Broad-based budding yeasts are seen in:
- A. Histoplasmosis
- B. Blastomycosis (Correct Answer)
- C. Candidiasis
- D. Coccidioidomycosis
Fungal Infections Explanation: ***Blastomycosis***
- This fungal infection is classically characterized by **broad-based budding yeasts** seen on microscopic examination.
- The yeast cells are typically large and have a characteristic wide connection between the mother and daughter cells during budding.
*Histoplasmosis*
- Characterized by **small, intracellular yeasts** often seen within macrophages.
- These yeasts do **not exhibit broad-based budding**.
*Candidiasis*
- Primarily presents as **pseudohyphae** (elongated yeast cells resembling hyphae) and budding yeasts (blastoconidia) with **narrow bases**.
- **True hyphae** may also be present depending on the species and growth conditions.
*Coccidioidomycosis*
- In tissue, it is characterized by **spherules** containing **endospores**, not budding yeasts.
- The mycelial form is found in culture or environmental samples.
Fungal Infections Indian Medical PG Question 7: A 45-year-old patient with a history of poorly controlled diabetes presents with sinus pain, nasal discharge, and facial swelling. A biopsy reveals broad, nonseptate hyphae branching at wide angles. What is the most likely causative agent?
- A. Aspergillus fumigatus
- B. Rhizopus spp. (Correct Answer)
- C. Candida albicans
- D. Cryptococcus neoformans
Fungal Infections Explanation: ***Rhizopus spp.***
- The patient's presentation with **sinus pain**, **nasal discharge**, **facial swelling**, and a history of **poorly controlled diabetes** is classic for **mucormycosis** (also known as zygomycosis).
- **Biopsy findings** of **broad, nonseptate hyphae branching at wide/irregular angles** are pathognomonic for mucormycosis, most commonly caused by *Rhizopus* species.
- Diabetes mellitus, particularly when poorly controlled with **ketoacidosis**, is a major risk factor for rhinocerebral mucormycosis.
*Aspergillus fumigatus*
- This fungus typically causes infections with **septate hyphae** that **branch at acute angles** (45 degrees), which is morphologically distinct from mucormycosis.
- While *Aspergillus* can cause invasive sinusitis in immunocompromised patients, the specific hyphal morphology (nonseptate, wide-angle branching) points away from it.
*Candida albicans*
- *Candida albicans* is a yeast that typically appears as **oval budding cells** and **pseudohyphae** on microscopy, not broad, nonseptate hyphae.
- While it can cause opportunistic infections in diabetic and immunocompromised patients, its microscopic appearance is entirely inconsistent with the biopsy findings.
*Cryptococcus neoformans*
- *Cryptococcus neoformans* is an **encapsulated yeast** that is typically identified by its **spherical or oval budding cells** with a characteristic **polysaccharide capsule** visible with India ink stain.
- It primarily causes **meningitis** and pulmonary infections in immunocompromised hosts, and its morphology (yeast, not hyphae) is entirely different from the described findings.
Fungal Infections Indian Medical PG Question 8: An 8-year-old child has localized non-cicatricial alopecia over scalp with itching and scales. The diagnosis is :
- A. Lichen planus
- B. Tinea Capitis (Correct Answer)
- C. Tinea Barbae
- D. Alopecia areata
Fungal Infections Explanation: ***Tinea Capitis***
- **Tinea capitis** typically presents as **localized, non-cicatricial alopecia** with features like **scaling**, **itching**, and broken hairs, which are consistent with the child's symptoms.
- It's a common **dermatophyte infection** of the scalp, particularly in children, caused by fungi like *Trichophyton* or *Microsporum*.
*Lichen planus*
- **Lichen planus** can cause alopecia, but it is typically a **cicatricial (scarring)** alopecia, unlike the non-cicatricial finding described.
- It is more commonly associated with **purplish, polygonal, pruritic papules** on the skin and mucous membranes.
*Tinea Barbae*
- **Tinea barbae** specifically affects the **beard and mustache area** in adult males and would not present as alopecia on the scalp in an 8-year-old child.
- It usually involves deep follicular inflammation with **pustules and nodules**.
*Alopecia areata*
- **Alopecia areata** is characterized by **smooth, circular patches of non-scarring hair loss** without associated scaling or significant itching.
- The presence of **scaling and itching** in this case makes alopecia areata less likely.
Fungal Infections Indian Medical PG Question 9: A 70 year old farmer, presented to you with complaints of yellowish discolouration of his finger nails for the past 6 months, he also gives history of recurrent episodes of itching in the groin for which he used to take local home made herbal remedy. On examination 3 of his toe nails also show similar change with tunneling. Which among the following is the best test for rapid confirmation of your diagnosis?
- A. Tzanck smear
- B. KOH mount (Correct Answer)
- C. Woods lamp
- D. Biopsy
Fungal Infections Explanation: ***KOH mount***
- A **KOH mount** (potassium hydroxide) dissolves keratinocytes, allowing for direct visualization of fungal elements such as **hyphae** and **spores** under a microscope. This is the **most rapid and cost-effective test** for confirming fungal infections like **onychomycosis**.
- The patient's presentation with **yellowish discoloration** and **"tunneling"** of nails (suggesting onycholysis and subungual hyperkeratosis), along with a history of recurrent groin itching (potentially **tinea cruris**), strongly points to a fungal infection.
*Tzanck smear*
- A **Tzanck smear** is primarily used to detect multinucleated giant cells in **herpesvirus infections** (e.g., herpes simplex, varicella-zoster).
- It is not useful for identifying fungal elements responsible for nail discoloration or suspected onychomycosis.
*Woods lamp*
- A **Woods lamp** uses ultraviolet light to detect specific fluorescent substances, particularly useful for diagnosing certain **bacterial infections** (e.g., *Corynebacterium minutissimum* in erythrasma) or some **tinea capitis** species (*Microsporum*).
- Most common dermatophytes causing onychomycosis **do not fluoresce** under a Wood's lamp, making it an unreliable diagnostic tool in this scenario.
*Biopsy*
- A **nail biopsy** (with histology and special stains like PAS) is a highly accurate diagnostic method for onychomycosis, especially when other tests are inconclusive.
- However, it is an **invasive procedure**, takes more time for results, and is generally not the **most rapid** initial test compared to a KOH mount.
Fungal Infections Indian Medical PG Question 10: A plant prick can produce sporotrichosis. Which of the following statements about sporotrichosis is false?
- A. Enlarged lymph nodes extending centripetally as a beaded chain are a characteristic finding
- B. Most cases are acquired via cutaneous inoculation
- C. It is an occupational disease of butchers, doctors (Correct Answer)
- D. Is a chronic mycotic disease that typically involves skin, subcutaneous tissue and regional lymphatics
Fungal Infections Explanation: ***It is an occupational disease of butchers, doctors***
- Sporotrichosis is an **occupational hazard for gardeners, florists, and agricultural workers** due to exposure to decaying plant matter, not typically for butchers or doctors.
- The disease is caused by **direct inoculation** of the fungus *Sporothrix schenckii* into the skin, often through a thorn prick or minor trauma.
*Most cases are acquired via cutaneous inoculation*
- This statement is **true** as sporotrichosis is primarily caused by **traumatic implantation** of fungal spores into the skin.
- Common sources include **thorns, splinters, sphagnum moss**, and other plant materials.
*Enlarged lymph nodes extending centripetally as a beaded chain are a characteristic finding*
- This statement is **true** and describes the classic **lymphocutaneous sporotrichosis**, where lesions and **nodular lymphangitis** track along lymphatic channels.
- The "beaded chain" appearance refers to the multiple subcutaneous nodules formed along the lymphatic vessels.
*Is a chronic mycotic disease that typically involves skin, subcutaneous tissue and regional lymphatics*
- This statement is **true** because sporotrichosis is a **slow-progressing fungal infection** that primarily affects the skin, the tissue just beneath the skin, and the lymphatics draining the infected area.
- While systemic dissemination can occur in immunocompromised individuals, the **cutaneous and lymphocutaneous forms** are most common.
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