Mycology Practice Questions

Q: A patient walking barefoot during his morning walk has developed a swelling in the foot. What is the probable diagnosis?

Madura foot. **Madura foot (Correct Answer)** - **Madura foot**, or mycetoma, is a **chronic granulomatous infection** often acquired through minor skin trauma, such as walking barefoot on contaminated soil - Classic presentation: **localized swelling, draining sinuses, and grain formation** - The image shows a **swollen foot** with signs of chronic infection, consistent with the progressive nature of Madura foot affecting subcutaneous tissues and eventually bone - Endemic in tropical regions including India, making this the most likely diagnosis given barefoot walking *Staphylococcus aureus (Incorrect)* - While *S. aureus* can cause various skin infections and swelling, it typically presents with **acute infections** (abscesses, cellulitis, folliculitis) - A **chronic, localized swelling with potential sinus tracts** that progresses over time is less typical for uncomplicated *S. aureus* infections - The context of barefoot walking on soil is more suggestive of fungal or actinomycotic infections *Botryomycosis (Incorrect)* - **Botryomycosis** is a rare chronic bacterial infection that causes granulomas and abscesses, often with "grains" similar to mycetoma - Typically caused by bacteria like *Staphylococcus aureus* or *Pseudomonas aeruginosa*, **not typically acquired directly from soil** - Though it presents with granulomas and "grains," the context of walking barefoot and the endemic nature of mycetoma in India makes Madura foot more likely *Tetanus (Incorrect)* - **Tetanus** is a severe neurological condition caused by the toxin of *Clostridium tetani*, entering through wounds - Presents with **muscle spasms, rigidity, and lockjaw** (trismus) - Does **not cause localized swelling or chronic granulomatous lesions** as shown in the image - Wrong clinical presentation entirely

Q: A carpenter presents with a nodule on dorsum of hand which ulcerates after few days and has not healed for last 2 months. Biopsy of lesion was performed and shown below. Diagnosis is:

Sporotrichosis. ***Sporotrichosis*** - The image shows **cigar-shaped yeast cells** (arrow), characteristic of *Sporothrix schenckii*, the causative agent of sporotrichosis. The presence of an **asteroid body** (asterisk) formed by eosinophilic material radiating from the yeast cell is also classic for sporotrichosis in tissue. - The history of a **carpenter** presenting with a nodule that ulcerates after trauma (e.g., from wood splinters) and doesn't heal is highly suggestive of **sporotrichosis**, often referred to as "rose gardener's disease" due to occupational exposure. *Chromomycosis* - Characterized by the presence of **sclerotic bodies** (also known as Medlar bodies or fumagoid bodies) which are darkly pigmented, thick-walled, round cells that divide by septation. - The clinical presentation is typically slow-growing, **verrucous plaques** or nodules, predominantly on the lower extremities, which are distinct from the ulcerating nodule seen here. *Lobomycosis* - Caused by *Lacazia loboi*, it presents with **chains of yeast cells** that are spherical or ovoid, thick-walled, and interconnected by short tubes. - Clinically, it typically manifests as **keloid-like lesions** or chronic nodular plaques, primarily in tropical and subtropical regions, and does not commonly ulcerate in the initial presentation like the case described. *Cutaneous histoplasmosis* - Caused by *Histoplasma capsulatum*, which appears as **small, oval yeast cells** (2-4 µm) within macrophages in tissue sections. - While it can manifest cutaneously, especially in immunocompromised individuals, the yeast cells are much smaller and do not have the distinct cigar-shape or form asteroid bodies seen in the image.

Q: A 25-year-old truck driver presents with history of fever for 3 days with altered sensorium for 1 day. On the way to hospital he had an episode of vomiting followed by seizures. On examination reflexes are brisk and neck stiffness was noted. Mannitol was given and Lumbar puncture was performed. The microscopic examination of CSF sample yields the view given below. What is the diagnosis?

Cryptococcus. ***Cryptococcus*** - The image provided depicts an **India ink stain** of CSF, which is characteristic for visualizing the large polysaccharide **capsule** of *Cryptococcus neoformans* as a **clear halo** against a dark background. - Clinical features of fever, altered sensorium, seizures, brisk reflexes, and **neck stiffness** are consistent with meningitis, and *Cryptococcus* is a common cause, particularly in immunocompromised individuals or those with environmental exposure (like a truck driver who might be exposed to bird droppings). *Pneumococcus* - *Streptococcus pneumoniae* (Pneumococcus) is a common cause of bacterial meningitis, but it is a **bacterium, not a fungus**, and would not show a distinct capsule with India ink stain. - Microscopic examination of CSF for Pneumococcus would typically reveal **Gram-positive diplococci**, not encapsulated yeast forms. *Enterococcus* - *Enterococcus* species are **Gram-positive cocci** that can cause meningitis, especially in neonates, the elderly, or hospitalized patients, but they are also **bacteria**. - They also would not present with a capsule visible by India ink staining; routine Gram stain would be used for their identification. *Listeria monocytogenes* - *Listeria monocytogenes* is a **Gram-positive rod** that causes meningitis, particularly in pregnant women, neonates, the elderly, and immunocompromised individuals. - Similar to the other bacterial options, it is identified by **Gram stain** and culture, and an India ink stain would not reveal encapsulated yeast.

Q: Identify the fungal organism in this slide stained with Gomori-methenamine silver stain. (AIIMS Nov 2017)

Acute angle branching, aspergillus. **Acute angle branching, aspergillus** - The image shows **septate hyphae** with **acute angle (45-degree) branching**, which is characteristic of *Aspergillus* species. - While *Aspergillus* can be identified by conidial heads in culture, in tissue sections stained with Gomori-methenamine silver (GMS) stain, these morphological features are key. *Acute angle branching, rhizopus* - **Rhizopus** species typically exhibit **non-septate or sparsely septate hyphae** with **irregular branching**, often at wide angles. - This morphology differs from the regularly septate, acutely branching hyphae seen in the image. *Right angle branching, aspergillus* - **Aspergillus** hyphae characteristically show **acute angle (45-degree) branching**, not right-angle branching. - The hyphae are also **septate**, a feature that is clearly visible in the image. *Right angle branching, mucor* - **Mucor** species, like other Mucorales (e.g., *Rhizopus*, *Lichtheimia*), are known for their **non-septate or sparsely septate hyphae** with **wide-angle (often right-angle) branching**. - The hyphae in the image are clearly septate and branch acutely, ruling out *Mucor*.

Q: A young male presents with the following itchy lesion for one month. All of the following genera can cause this kind of lesion except:

Aspergillus. ***Aspergillus*** - **Aspergillus** species are opportunistic fungi that primarily cause **invasive aspergillosis** in immunocompromised patients, affecting lungs and sinuses rather than superficial skin infections. - Unlike dermatophytes, **Aspergillus** does not commonly cause **tinea (ringworm)** infections or the characteristic **annular, itchy lesions** seen in healthy individuals. *Trichophyton* - **Trichophyton** is a major dermatophyte genus causing various forms of **tinea**, including **tinea corporis**, which presents as itchy, ring-like lesions with central clearing. - This genus is responsible for **athlete's foot (tinea pedis)** and **jock itch (tinea cruris)**, commonly producing the scaly, erythematous lesions described. *Microsporum* - **Microsporum** is another important dermatophyte genus that causes **tinea corporis** and **tinea capitis**, manifesting as circular, itchy, scaling patches. - Infections by **Microsporum** typically show **well-demarcated borders** with central clearing, matching the clinical presentation of the described lesion. *Epidermophyton* - **Epidermophyton floccosum** is a dermatophyte that commonly causes **tinea cruris** and **tinea corporis**, producing characteristic **annular, pruritic lesions**. - While it cannot infect hair (no **tinea capitis**), it readily causes **superficial skin infections** with the typical ring-like appearance and scaling borders.

Q: The given KOH mount of a patient shows:

Budding yeasts and pseudohyphae. ***Budding yeasts and pseudohyphae*** - The image clearly displays structures characteristic of **budding yeast cells** and elongated forms consistent with **pseudohyphae**, which are typical findings in candidiasis. - This morphology is a hallmark of *Candida* species, commonly seen in KOH mounts from samples like vaginal swabs or skin scrapings for diagnosing fungal infections. *Spaghetti and meat ball appearance* - This description refers to the characteristic appearance of *Malassezia furfur* in KOH preparations, associated with **tinea versicolor**, showing short, curved hyphae and spherical yeast forms. - The image provided does not show the distinctive short, curved hyphae and clusters of yeast cells indicative of **Spaghetti and meat ball appearance**. *Clusters of pigmented cells* - This description would suggest the presence of **melanocytes** or possibly **pigmented fungi** (phaeohyphomycosis), which can be seen in certain fungal infections but are not what is depicted here. - The structures in the image appear to be fungal elements and are not distinctly pigmented cells formed in clusters. *Septate hyphae* - **Septate hyphae** are long, filamentous structures with regular cross-walls, characteristic of dermatophytes like *Trichophyton* or *Microsporum* species, causing ringworm. - While there are filamentous structures, they are primarily **pseudohyphae** (constricted at the septa, resembling a chain of elongated budding cells) rather than true septate hyphae, and are accompanied by distinct budding yeast forms.

Q: A patient has the following rash in the groin. Which of the following cannot be a cause?

Aspergillus. ***Aspergillus*** - **Aspergillus** is a **mold (filamentous fungus)**, NOT a dermatophyte, and therefore **cannot cause tinea cruris** (jock itch). - Dermatophytes (Trichophyton, Microsporum, Epidermophyton) are specialized fungi that digest keratin and cause superficial skin infections with characteristic ringworm patterns. - Aspergillus typically causes invasive infections in immunocompromised patients (invasive aspergillosis), allergic bronchopulmonary aspergillosis (ABPA), or rarely deep cutaneous infections in severely immunocompromised individuals—not superficial groin rashes. - **Key distinction:** Tinea cruris = dermatophyte infection; Aspergillus = opportunistic mold *Microsporum* - **Microsporum** species are dermatophytes that CAN cause tinea cruris, though less commonly than Trichophyton and Epidermophyton. - *M. canis* is the most common species, typically causing **tinea capitis** (scalp) and **tinea corporis** (body), but can extend to the groin area. - While not the most frequent cause, it remains a possible etiology and should not be excluded. *Epidermophyton* - **Epidermophyton floccosum** is one of the **most common causes** of tinea cruris. - Presents with itchy, erythematous, scaling patches with well-defined, elevated borders in the inguinal folds. - Thrives in warm, moist environments, making the groin an ideal location. - **Classic presentation:** bilateral involvement with central clearing and advancing scaly borders. *Trichophyton* - **Trichophyton rubrum** is the **MOST common** cause of tinea cruris worldwide, followed by **T. mentagrophytes**. - Causes characteristic pruritic, erythematous, annular or serpiginous lesions with raised, scaly borders. - T. rubrum accounts for the majority of dermatophyte infections in the groin, feet, and nails.

Q: A patient with HIV develops fever weight loss and diarrhea. Fecal examination shows isospora belli. He was given treatment with TMP - SMX. Diarrhea subsided but fever persisted. Bone marrow examination showed the following picture with intracellular fungi. Which of the following statements is wrong? (AIIMS Nov 2017)

It cannot be grown in SDA. ***It cannot be grown in SDA*** - The image shows **intracellular budding yeast** consistent with *Histoplasma capsulatum*. - *Histoplasma capsulatum* **can be cultured** on Sabouraud Dextrose Agar (SDA) as a mold at room temperature, making the statement that it cannot be grown in SDA incorrect. *Spores are infective form* - The infective form of *Histoplasma capsulatum* is indeed **microconidia (spores)**, which are inhaled into the lungs. - These spores convert to yeast forms in the host's body. *It is intracellular budding yeast* - The image clearly depicts **intracellular yeast cells within a macrophage**, a hallmark of *Histoplasma capsulatum* infection. - These yeast cells reproduce by **budding**, which is visible as smaller structures emerging from the main yeast cell. *It can cause systemic disease* - *Histoplasma capsulatum* is known to cause **histoplasmosis**, which can range from asymptomatic to severe disseminated disease, especially in **immunocompromised individuals like HIV patients**. - Systemic disease involves the spread of the fungus to organs beyond the lungs, such as the **bone marrow, liver, and spleen**, as evidenced by the bone marrow examination in the question.

Q: Mycetoma, a chronic, specific, granulomatous, destructive disease involving the skin and subcutaneous tissue:

may be caused by fungi or bacteria. ***may be caused by fungi or bacteria*** - Mycetoma can be caused by either **eumycetes (true fungi)**, leading to **eumycetoma**, or by certain **aerobic actinomycetes (bacteria)**, resulting in **actinomycetoma** [1]. - Both forms present with similar clinical features, including **granulomatous inflammation** and the formation of **grains** or granules. *involves the superficial structure only* - Mycetoma is characterized by its **destructive nature**, progressively involving **deep tissues** like fascia, muscle, and even bone, not just superficial structures [1]. - The disease often leads to **deformity** and **loss of function** due to deep tissue invasion. *frequently causes trophic changes* - While mycetoma leads to significant tissue destruction and deformity, **trophic changes** (e.g., changes in skin, hair, and nails due to nerve damage) are not its primary or most characteristic feature. - The main complications are related to **tissue destruction**, **secondary infections**, and **amputation**. *is a blood-borne infection* - Mycetoma is acquired through **traumatic inoculation** of the causative organism into the skin, typically via thorns or splinters. - It is a **localized infection** and does not spread via the bloodstream; systemic dissemination is very rare.

Question 1

A patient walking barefoot during his morning walk has developed a swelling in the foot. What is the probable diagnosis?

Accepted Answer

Madura foot

Answer

Staphylococcus aureus

Answer

Botryomycosis

Answer

Tetanus

Question 2

A carpenter presents with a nodule on dorsum of hand which ulcerates after few days and has not healed for last 2 months. Biopsy of lesion was performed and shown below. Diagnosis is:

Accepted Answer

Sporotrichosis

Answer

Chromomycosis

Answer

Lobomycosis

Answer

Cutaneous histoplasmosis

Question 3

A 25-year-old truck driver presents with history of fever for 3 days with altered sensorium for 1 day. On the way to hospital he had an episode of vomiting followed by seizures. On examination reflexes are brisk and neck stiffness was noted. Mannitol was given and Lumbar puncture was performed. The microscopic examination of CSF sample yields the view given below. What is the diagnosis?

Accepted Answer

Cryptococcus

Answer

Pneumococcus

Answer

Enterococcus

Answer

Listeria monocytogenes

Question 4

Identify the fungal organism in this slide stained with Gomori-methenamine silver stain. (AIIMS Nov 2017)

Accepted Answer

Acute angle branching, aspergillus

Answer

Acute angle branching, rhizopus

Answer

Right angle branching, aspergillus

Answer

Right angle branching, mucor

Question 5

A young male presents with the following itchy lesion for one month. All of the following genera can cause this kind of lesion except:

Accepted Answer

Aspergillus

Answer

Trichophyton

Answer

Microsporum

Answer

Epidermophyton

Question 6

The given KOH mount of a patient shows:

Accepted Answer

Budding yeasts and pseudohyphae

Answer

Spaghetti and meat ball appearance

Answer

Clusters of pigmented cells

Answer

Septate hyphae

Question 7

A patient has the following rash in the groin. Which of the following cannot be a cause?

Accepted Answer

Aspergillus

Answer

Microsporum

Answer

Epidermophyton

Answer

Trichophyton

Question 8

Based on the image showing intracellular yeast inside a macrophage with a peripheral crescent-shaped nucleus, which statement is true regarding Histoplasma capsulatum?

Accepted Answer

It causes disseminated disease in immunocompromised patients

Answer

It cannot be grown in SDA

Answer

It is a monomorphic fungus that exists only as yeast

Answer

Its yeast form shows broad-based budding

Question 9

A patient with HIV develops fever weight loss and diarrhea. Fecal examination shows isospora belli. He was given treatment with TMP - SMX. Diarrhea subsided but fever persisted. Bone marrow examination showed the following picture with intracellular fungi. Which of the following statements is wrong? (AIIMS Nov 2017)

Accepted Answer

It cannot be grown in SDA

Answer

Spores are infective form

Answer

It is intracellular budding yeast

Answer

It can cause systemic disease

Question 10

Mycetoma, a chronic, specific, granulomatous, destructive disease involving the skin and subcutaneous tissue:

Accepted Answer

may be caused by fungi or bacteria

Answer

involves the superficial structure only

Answer

frequently causes trophic changes

Answer

is a blood-borne infection

Mycology — MCQs

Mycology — MCQs

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