Mycology Practice Questions

Q: Fungal spores may be produced in which of the following ways?

All of the above. ### Explanation Fungi reproduce primarily through the formation of **spores**, which can be sexual or asexual. The morphology and arrangement of these spores are key diagnostic features in medical mycology. **Why "All of the above" is correct:** Fungi exhibit diverse mechanisms for spore production depending on the species and environmental conditions: * **Singly:** Some fungi produce solitary spores. For example, **Blastomyces** produces single terminal conidia (the "lollipop" appearance). * **In chains:** Many fungi, most notably **Aspergillus** and **Penicillium**, produce conidia in long, linear chains (catenulate) from specialized structures called phialides. * **In sporangium:** Members of the order Mucorales (e.g., **Rhizopus, Mucor**) produce asexual spores (sporangiospores) within a sac-like structure called a **sporangium**. When the sporangial wall ruptures, the spores are released. **Analysis of Options:** * **Option A, B, and C** are all correct but incomplete on their own. Since fungi utilize all three methods for dissemination and survival, "All of the above" is the most accurate choice. **High-Yield Clinical Pearls for NEET-PG:** * **Asexual Spores:** These include Conidia (formed on conidiophores) and Sporangiospores (formed within a sporangium). * **Sexual Spores:** Remember the mnemonic **BASE**—**B**asidiospores, **A**scospores, **S**ygospores (Zygospores), and **E**ospores (Oospores). * **Arthrospores:** Formed by fragmentation of hyphae (e.g., *Coccidioides immitis*, *Dermatophytes*). * **Chlamydospores:** Thick-walled resting spores (e.g., *Candida albicans* produces terminal chlamydospores on Cornmeal Agar).

Q: "Asteroid bodies" and "cigar shaped globi" may be produced by which of the following?

Sporotrichosis. **Explanation:** The correct answer is **Sporotrichosis**, a subcutaneous mycosis caused by the dimorphic fungus *Sporothrix schenckii*. **Why it is correct:** * **Asteroid Bodies:** These are found in tissue sections and represent a **Splendore-Hoeppli phenomenon**. They consist of a central yeast cell surrounded by radiating eosinophilic material (antigen-antibody complexes). * **Cigar-shaped Globi:** In its yeast phase (at 37°C or in tissue), *Sporothrix* typically appears as pleomorphic, elongated, or fusiform budding cells, often described as "cigar-shaped." **Analysis of Incorrect Options:** * **A. Sporothrix:** While *Sporothrix* is the causative agent, the question asks what "produces" these features. In medical entrance exams, the disease entity (**Sporotrichosis**) is often preferred over the genus name when describing pathological findings seen *in vivo*. * **C. Phialophora:** This is a causative agent of **Chromoblastomycosis**, characterized by "Medlar bodies" (Copper penny bodies/sclerotic bodies), not asteroid bodies. * **D. Aspergillus:** This fungus is characterized by septate hyphae with acute-angle (45°) branching and fruiting bodies, not cigar-shaped yeasts. **Clinical Pearls for NEET-PG:** * **Occupation:** Classically associated with gardeners and florists (traumatic inoculation via thorns), hence called **"Rose Gardener’s Disease."** * **Clinical Presentation:** Presents as a linear chain of nodules along the lymphatics (**Lymphocutaneous sporotrichosis**). * **Culture:** At 25°C, it shows a "Flower-like" or "Daisy-petal" arrangement of conidia. * **Treatment:** Drug of choice is **Itraconazole**. Historically, saturated solution of potassium iodide (SSKI) was used.

Q: Cigar bodies are seen in which condition?

Sporotrichosis. **Explanation:** **Sporotrichosis** is a subcutaneous fungal infection caused by the dimorphic fungus *Sporothrix schenckii*. The correct answer is **A** because "Cigar bodies" are the characteristic tissue form of this fungus. * **Why it is correct:** In tissue biopsies (at 37°C), *Sporothrix schenckii* exists as pleomorphic, elongated, fusiform yeast cells measuring 1–3 µm by 3–10 µm. Their elongated shape resembles a cigar, hence the term **"Cigar bodies."** These are often difficult to visualize on routine H&E stains and are better seen with PAS or GMS stains. **Why other options are incorrect:** * **Chromoblastomycosis:** Characterized by **Medlar bodies** (Sclerotic bodies/Copper-penny bodies), which are thick-walled, dark brown, multiseptate fungal cells. * **Mycetoma:** Characterized by the presence of **grains** or granules (sulfur granules in actinomycetoma or fungal hyphae in eumycetoma) draining from sinuses. * **Basidiomycosis:** Typically presents as subcutaneous zygomycosis (e.g., *Conidiobolus*), characterized by thin-walled, sparsely septate hyphae often surrounded by an eosinophilic halo (**Splendore-Hoeppli phenomenon**). **High-Yield Clinical Pearls for NEET-PG:** * **Occupational Hazard:** Known as **"Rose Gardener’s Disease"** due to traumatic inoculation via thorns. * **Clinical Presentation:** Presents as a linear chain of nodules along the lymphatic drainage (**Sporotrichoid spread**). * **Asteroid Bodies:** In tissue, yeast cells may be surrounded by eosinophilic radiating processes (Splendore-Hoeppli phenomenon), termed Asteroid bodies. * **Culture:** At 25°C, it shows a "Flower-like" or **"Daisy petal"** arrangement of conidia. * **Treatment:** Drug of choice is **Itraconazole**. Historically, saturated solution of potassium iodide (SSKI) was used.

Q: Which dermatophyte species does not involve the nail?

Microsporum. ### Explanation The correct answer is **Microsporum**. The classification of dermatophytes into three genera—*Trichophyton*, *Microsporum*, and *Epidermophyton*—is based on the specific keratinized tissues they can invade (skin, hair, and nails). **1. Why Microsporum is correct:** *Microsporum* species primarily infect the **hair and skin**. They lack the biochemical capability to effectively invade the nail plate. Therefore, it is the only genus among the three that does not cause Onychomycosis (nail infection). **2. Why the other options are incorrect:** * **Trichophyton:** This is the most versatile genus. It can involve all three keratinized structures: **Skin, Hair, and Nails**. *T. rubrum* is the most common cause of Onychomycosis worldwide. * **Epidermophyton:** This genus involves the **Skin and Nails** but notably **does not involve the hair**. *Epidermophyton floccosum* is a common cause of Tinea cruris and Onychomycosis. **3. High-Yield Clinical Pearls for NEET-PG:** To quickly memorize the tissue involvement, use this simple table: | Genus | Skin | Hair | Nails | | :--- | :---: | :---: | :---: | | **Trichophyton** | Yes | Yes | Yes | | **Microsporum** | Yes | Yes | **No** | | **Epidermophyton** | Yes | **No** | Yes | * **Wood’s Lamp Examination:** *Microsporum* species (like *M. audouinii* and *M. canis*) typically show a brilliant greenish fluorescence, whereas most *Trichophyton* species (except *T. schoenleinii*) do not fluoresce. * **Macroconidia Shape:** *Microsporum* has spindle-shaped macroconidia, *Trichophyton* has pencil-shaped, and *Epidermophyton* has club-shaped macroconidia.

Q: Which one of the following is diagnosed by latex agglutination for antigen in CSF?

Cryptococcus. **Explanation:** **1. Why Cryptococcus is Correct:** The diagnosis of **Cryptococcal meningitis** relies heavily on the detection of the capsular polysaccharide antigen (GXM) in the Cerebrospinal Fluid (CSF) or serum. The **Latex Agglutination (LA) test** uses latex beads coated with specific antibodies that clump (agglutinate) in the presence of this antigen. It is highly sensitive (>90%) and specific, often providing a diagnosis faster than a fungal culture and being more sensitive than an India Ink preparation (which can be negative in early or low-burden infections). **2. Why the Other Options are Incorrect:** * **Aspergillosis:** Diagnosis typically involves the **Galactomannan** antigen assay (via ELISA) or Beta-D-Glucan testing, primarily in serum or Bronchoalveolar Lavage (BAL) fluid, rather than CSF latex agglutination. * **Candida:** While Beta-D-Glucan is a marker for invasive candidiasis, there is no routine, reliable latex agglutination test for Candida antigen in the CSF used for clinical diagnosis. * **Histoplasmosis:** Diagnosis is usually made via **Urinary or Serum antigen** detection (ELISA) or histopathology showing intracellular yeast in macrophages. CSF involvement is rare and not typically diagnosed via LA. **3. High-Yield Clinical Pearls for NEET-PG:** * **India Ink:** Shows a "clear halo" (capsule) against a dark background but is less sensitive than the LA test. * **Culture:** Sabouraud Dextrose Agar (SDA) is used; colonies appear creamy/mucoid. * **Stains:** **Mucicarmine** is specific for the capsule (stains it red); **Masson-Fontana** stains the melanin in the cell wall. * **Risk Factor:** Strongly associated with low CD4 counts (<100 cells/µL) in HIV/AIDS patients.

Q: Candida is most often implicated in causation of which condition?

Thrush. **Explanation:** **Candida albicans** is a polymorphic opportunistic fungus that exists as part of the normal flora in the oral cavity, gastrointestinal tract, and vagina. **Why Thrush is the Correct Answer:** **Oral Thrush (Pseudomembranous Candidiasis)** is the most common clinical manifestation of *Candida* infection. It is characterized by creamy white, curd-like patches on the tongue and buccal mucosa that can be easily scraped off, leaving behind an erythematous (red) base. It occurs frequently in neonates, denture wearers, and immunocompromised individuals (e.g., HIV/AIDS, patients on broad-spectrum antibiotics or inhaled corticosteroids). **Analysis of Incorrect Options:** * **A. Conjunctivitis:** Most commonly caused by viruses (Adenovirus) or bacteria (*Staphylococcus aureus*, *Haemophilus influenzae*). While *Candida* can cause endophthalmitis (usually via hematogenous spread), it is a rare cause of primary conjunctivitis. * **B. Tinea capitis:** This is a fungal infection of the scalp caused by **Dermatophytes** (genera *Trichophyton* and *Microsporum*), not *Candida*. Dermatophytes require keratin for growth, whereas *Candida* prefers moist mucosal surfaces. * **C. Dese rheumatism:** This appears to be a distractor or a misspelling of "Desert Rheumatism," which is a clinical manifestation of **Coccidioidomycosis** (caused by *Coccidioides immitis*), characterized by fever, joint pain, and erythema nodosum. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** *Candida* shows Gram-positive budding yeast cells and **pseudohyphae**. * **Germ Tube Test (Reynolds-Braude Phenomenon):** The definitive rapid diagnostic test for *C. albicans*. * **Culture:** Produces "creamy white" colonies on Sabouraud Dextrose Agar (SDA). * **Chlamydospores:** Produced on Cornmeal agar at 25°C. * **Risk Factors:** Diabetes mellitus, prolonged antibiotic use, and T-cell deficiency are major predispositions.

Q: A 31-year-old woman has had vulvar pruritus along with a thick, whitish, odorless, globular vaginal discharge for the past week. On pelvic examination, the cervix appears erythematous, but there are no erosions or masses. A Pap smear shows budding cells and pseudo hyphae. No dysplastic cells are present. Which of the following infectious agents is most likely to produce these findings?

Candida albicans. ### Explanation The clinical presentation and laboratory findings are classic for **Vulvovaginal Candidiasis (VVC)**, most commonly caused by *Candida albicans*. **Why the correct answer is right:** * **Clinical Features:** The "thick, whitish, odorless, globular" discharge is often described as **curd-like** or **cottage cheese-like**. Vulvar pruritus (itching) is the hallmark symptom. * **Microscopy:** The Pap smear (or a KOH mount) showing **budding yeast cells and pseudohyphae** is the definitive diagnostic feature for *Candida*. While Pap smears are for cytology, they frequently incidentally detect fungal elements. * **Physical Exam:** Erythema of the cervix and vaginal walls is common due to inflammation, but unlike other infections, the discharge remains odorless. **Why the incorrect options are wrong:** * **Chlamydia trachomatis:** Typically causes a mucopurulent cervicitis. It is an obligate intracellular bacterium and would not show pseudohyphae on microscopy. * **Neisseria gonorrhoeae:** Causes purulent cervical discharge and pelvic inflammatory disease. Diagnosis is via Gram stain (Gram-negative diplococci) or NAAT, not fungal elements. * **Trichomonas vaginalis:** Characterized by a **foul-smelling, greenish-yellow, frothy** discharge. On examination, one would expect a "strawberry cervix" (punctate hemorrhages) and motile flagellated organisms on a wet mount. **High-Yield Pearls for NEET-PG:** * **Risk Factors:** Pregnancy, Diabetes Mellitus, recent antibiotic use, and immunosuppression (HIV). * **pH Level:** In Candidiasis, the vaginal pH is typically **normal ( 4.5. * **Treatment:** First-line treatment is topical or oral azoles (e.g., **Fluconazole** 150mg single dose). Note: Oral fluconazole is contraindicated in pregnancy; use topical clotrimazole instead.

Q: Which of the following methods is used for the rapid identification of Candida?

Germ tube method. ### Explanation **Correct Option: B. Germ tube method** The **Germ tube test** (also known as the Reynolds-Braude phenomenon) is the gold standard for the rapid presumptive identification of *Candida albicans* and *Candida dubliniensis*. * **Mechanism:** When *C. albicans* cells are incubated in human or rabbit serum at 37°C for 2–3 hours, they produce short, lateral hyphal extensions called **germ tubes**. * **Key Feature:** A true germ tube has **no constriction** at its point of origin from the parent yeast cell (unlike pseudohyphae). This test provides results within hours, making it significantly faster than traditional culture. **Analysis of Incorrect Options:** * **A & D (Culture in solid/liquid media):** While *Candida* grows readily on Sabouraud Dextrose Agar (SDA) or in liquid broth, these methods require 24–48 hours for visible growth. They are used for isolation but are not considered "rapid" identification methods compared to the germ tube test. * **C (Growth in an animal model):** Historically, the "Rabbit Pathogenicity Test" was used to confirm virulence, but it is expensive, time-consuming, and ethically restricted. It is never used for routine clinical identification. **High-Yield Clinical Pearls for NEET-PG:** * **Chlamydospore Formation:** *C. albicans* produces thick-walled terminal chlamydospores on **Cornmeal Agar** (Dalmau technique). * **CHROMagar:** A specialized differential medium where *Candida* species produce different colors (e.g., *C. albicans* is light green, *C. tropicalis* is blue/metallic blue). * **Drug Resistance:** *C. glabrata* and *C. krusei* are notorious for intrinsic or emerging resistance to Azoles. * **Morphology:** *Candida* is a "dimorphic" fungus in a unique sense—it exists as yeast at room temperature and forms hyphae/germ tubes at body temperature (37°C).

Q: Which of the following is true about Histoplasma capsulatum?

It is a dimorphic fungus.. ### Explanation **1. Why Option A is Correct:** *Histoplasma capsulatum* is a classic **systemic dimorphic fungus**. Dimorphism is the ability of a fungus to exist in two distinct morphological forms depending on environmental conditions (primarily temperature). * **At 25°C (Soil/Culture):** It grows as a **mold** with characteristic tuberculate macroconidia (thick-walled spores with finger-like projections). * **At 37°C (In host tissue):** It transforms into an **intracellular yeast**, typically found within macrophages. **2. Why the Other Options are Incorrect:** * **Option B:** **Moniliasis** is an older clinical term for **Candidiasis**, caused by *Candida albicans*, not *Histoplasma*. * **Option C:** **Valley Fever** (Desert Rheumatism) is caused by ***Coccidioides immitis***. *Histoplasma* causes "Darling’s Disease" or "Ohio Valley Disease." * **Option D:** Despite its name (*capsulatum*), **it is NOT capsulated**. The name was a historical misnomer; the "halo" seen around the yeast cells in tissue sections is actually an artifact caused by cytoplasm shrinkage away from the cell wall during staining. **3. High-Yield Clinical Pearls for NEET-PG:** * **Habitat:** Found in soil enriched with **bird or bat droppings** (guano); common among cave explorers (spelunkers). * **Pathogenesis:** It is an **obligate intracellular parasite** of the Reticuloendothelial system (Macrophages). * **Diagnosis:** * **Microscopy:** Small oval yeasts inside macrophages (Gomori Methenamine Silver/PAS stain). * **Culture:** Sabouraud Dextrose Agar (SDA) shows white-to-brown filamentous colonies. * **Clinical Presentation:** Often mimics Tuberculosis (calcified granulomas in lungs/spleen). In HIV patients, it causes disseminated disease.

Question 1

Fungal spores may be produced in which of the following ways?

Accepted Answer

All of the above

Answer

Singly

Answer

In chains

Answer

In sporangium

Question 2

"Asteroid bodies" and "cigar shaped globi" may be produced by which of the following?

Accepted Answer

Sporotrichosis

Answer

Sporothrix

Answer

Phialophora

Answer

Aspergillus

Question 3

Cigar bodies are seen in which condition?

Accepted Answer

Sporotrichosis

Answer

Chromoblastomycosis

Answer

Mycetoma

Answer

Basidiomycosis

Question 4

Which dermatophyte species does not involve the nail?

Accepted Answer

Microsporum

Answer

Trichophyton

Answer

Epidermophyton

Answer

None of the above

Question 5

Which one of the following is diagnosed by latex agglutination for antigen in CSF?

Accepted Answer

Cryptococcus

Answer

Aspergillosis

Answer

Candida

Answer

Histoplasmosis

Question 6

Candida is most often implicated in causation of which condition?

Accepted Answer

Thrush

Answer

Conjunctivitis

Answer

Tinea capitis

Answer

Dese rheumatism

Question 7

A 31-year-old woman has had vulvar pruritus along with a thick, whitish, odorless, globular vaginal discharge for the past week. On pelvic examination, the cervix appears erythematous, but there are no erosions or masses. A Pap smear shows budding cells and pseudo hyphae. No dysplastic cells are present. Which of the following infectious agents is most likely to produce these findings?

Accepted Answer

Candida albicans

Answer

Chlamydia trachomatis

Answer

Neisseria gonorrhoeae

Answer

Trichomonas vaginalis

Question 8

Which of the following methods is used for the rapid identification of Candida?

Accepted Answer

Germ tube method

Answer

Culture in solid media

Answer

Growth in an animal model

Answer

Culture in liquid media

Question 9

All are true about Madura mycetoma except?

Accepted Answer

Presented as a painful nodular lesion for many months

Answer

Fungal infection

Answer

Discharging sinuses

Answer

Bone involvement seen

Question 10

Which of the following is true about Histoplasma capsulatum?

Accepted Answer

It is a dimorphic fungus.

Answer

It is the causative organism of moniliasis.

Answer

It is the causative organism of valley fever.

Answer

It is capsulated.

Mycology — MCQs

Mycology — MCQs

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