Mycology Practice Questions

Q: Sulphur granules are composed of?

Fungal filaments. **Explanation:** **Sulphur granules** are characteristic macroscopic structures found in the pus of patients with **Actinomycosis** (caused by *Actinomyces israelii*) and certain fungal infections like **Mycetoma** (Madura foot). 1. **Why the correct answer is right:** Despite the name, sulphur granules contain no actual sulphur. They are organized micro-colonies of the causative organism. In the context of fungal mycetoma (Eumycetoma), these granules are composed of a dense, tangled mass of **fungal filaments** (hyphae) cemented together by a proteinaceous matrix. In Actinomycosis (a bacterial infection that mimics fungi), they consist of branching bacterial filaments. Under a microscope, these granules often show a "sunburst" appearance due to peripheral clubbing (Splendore-Hoeppli phenomenon). 2. **Why the incorrect options are wrong:** * **Leukocytes:** While pus contains neutrophils and other leukocytes, they form the inflammatory response *around* the granule, not the structural core of the granule itself. * **Erythrocytes:** Red blood cells are not a structural component of these infectious colonies. * **Keratinocytes:** These are skin cells. While mycetoma involves the skin and subcutaneous tissue, keratinocytes do not constitute the granule. **High-Yield Clinical Pearls for NEET-PG:** * **Actinomyces israelii:** Gram-positive, non-acid-fast, anaerobic branching bacilli. Most common cause of "lumpy jaw." * **Eumycetoma:** Caused by fungi (e.g., *Madurella mycetomatis*); granules are usually black or white. * **Actinomycetoma:** Caused by aerobic actinomycetes (e.g., *Nocardia*); granules are usually white, yellow, or red. * **Splendore-Hoeppli Phenomenon:** The deposition of antigen-antibody complexes around the filaments, appearing as eosinophilic radiating processes.

Q: Homosexual men with AIDS are most likely to exhibit which of the following conditions?

Pneumocystis pneumonia. **Explanation:** **Pneumocystis pneumonia (PCP)**, caused by the fungus *Pneumocystis jirovecii*, is the most common opportunistic infection in patients with AIDS. In the context of the NEET-PG, it is crucial to remember that while the epidemiology of HIV has evolved, PCP remains a hallmark AIDS-defining illness, particularly in patients with CD4+ T-cell counts below 200 cells/mm³. **Analysis of Options:** * **Option B (Correct):** *Pneumocystis jirovecii* is an opportunistic pathogen that specifically exploits the cell-mediated immunodeficiency seen in AIDS. Homosexual men (MSM) were among the first cohorts identified with this association, and it remains a leading cause of morbidity and mortality in untreated HIV. * **Option A (Incorrect):** HTLV-II is primarily associated with intravenous drug users (IDUs) rather than homosexual men. While co-infections occur, it is not the "most likely" condition compared to PCP. * **Option C (Incorrect):** HIV selectively infects and destroys CD4+ (inducer/helper) T cells. Therefore, AIDS is characterized by a **profound depletion** (decrease) of these cells, leading to an inversion of the normal CD4:CD8 ratio. **High-Yield Clinical Pearls for NEET-PG:** * **Prophylaxis:** Start Trimethoprim-Sulfamethoxazole (TMP-SMX) when CD4 count < 200 cells/mm³. * **Diagnosis:** Silver stains (Gomori Methenamine Silver - GMS) or Direct Fluorescent Antibody (DFA) testing of induced sputum or bronchoalveolar lavage (BAL) showing "crushed ping-pong ball" shaped cysts. * **Radiology:** Classic "ground-glass opacities" (GGO) on HRCT and bilateral perihilar infiltrates on X-ray. * **Treatment:** High-dose TMP-SMX is the drug of choice; add steroids if PaO₂ 35 mmHg.

Q: A female presented with thick white discharge and pruritus. What is the etiological agent?

Candida. ### Explanation The clinical presentation of **thick, white, curd-like (cottage cheese) discharge** associated with intense **vulvovaginal pruritus** (itching) is the classic hallmark of **Vulvovaginal Candidiasis**, most commonly caused by *Candida albicans*. #### Why Candida is Correct: * **Clinical Features:** The hallmark is pruritus and a non-foul-smelling, thick, adherent discharge. * **Diagnosis:** On microscopy (KOH mount), it shows pseudohyphae and budding yeast cells. The vaginal pH is typically **normal (<4.5)**. #### Why Other Options are Incorrect: * **Gardnerella vaginalis:** Causes **Bacterial Vaginosis**. It presents with a thin, homogenous, grayish-white discharge with a characteristic **fishy odor** (positive Whiff test). Pruritus is usually absent, and "Clue cells" are seen on microscopy. * **Trichomonas vaginalis:** Causes **Trichomoniasis**, a sexually transmitted infection. It presents with a **profuse, frothy, greenish-yellow** discharge and a "strawberry cervix" (punctate hemorrhages). * **Gonococci:** Causes **Gonorrhea**, primarily resulting in cervicitis or Pelvic Inflammatory Disease (PID). It presents with a purulent endocervical discharge rather than isolated thick white vaginal discharge. #### NEET-PG High-Yield Pearls: 1. **Risk Factors for Candida:** Diabetes mellitus, pregnancy, recent broad-spectrum antibiotic use, and immunosuppression. 2. **Treatment:** Drug of choice is **Fluconazole** (150 mg single oral dose) or topical Clotrimazole. 3. **pH Differentiation:** In Candidiasis, pH is 4.5**. 4. **Recurrent Candidiasis:** Defined as $\geq$4 episodes per year; requires long-term maintenance therapy with Fluconazole.

Q: Which of the following organisms cannot be cultured?

Pneumocystis jiroveci. **Explanation:** The correct answer is **Pneumocystis jiroveci**. **1. Why Pneumocystis jiroveci is correct:** *Pneumocystis jiroveci* (formerly *P. carinii*) is an atypical fungus that lacks ergosterol in its cell membrane. It is considered **obligate to the human host** and, despite numerous attempts, **cannot be grown in routine laboratory culture media** (axenic culture). Diagnosis relies heavily on microscopic visualization using special stains (Gomori Methenamine Silver or Direct Fluorescent Antibody) from clinical samples like Bronchoalveolar Lavage (BAL). **2. Why the other options are incorrect:** * **Klebsiella rhinoscleromatis (Option A):** This is a subspecies of *K. pneumoniae* that causes Rhinoscleroma (chronic granulomatous infection of the nose). It **can be cultured** on standard media like Blood Agar or MacConkey agar, appearing as large, mucoid colonies. * **Klebsiella ozaenae (Option B):** Associated with atrophic rhinitis (ozena), this organism is also **culturable** on routine laboratory media. * **Klebsiella granulomatis (Option C):** Formerly known as *Calymmatobacterium granulomatis*, it causes Granuloma Inguinale (Donovanosis). While it is **difficult to culture** and does not grow on routine agar, it can be grown in **yolk sacs of embryonated eggs** or specialized co-culture systems. In clinical practice, it is diagnosed by identifying "Donovan bodies" in tissue smears. **Clinical Pearls for NEET-PG:** * **Non-culturable organisms (High-Yield):** *Mycobacterium leprae*, *Treponema pallidum*, and *Pneumocystis jiroveci*. * **Pneumocystis prophylaxis:** Indicated in HIV patients when CD4 count falls below **200 cells/mm³**. Drug of choice: **TMP-SMX**. * **Stain of choice:** Gomori Methenamine Silver (GMS) shows "crushed ping-pong ball" appearance of cysts.

Q: Which of the following is NOT a cause of Madura foot?

Mucor. **Explanation:** **Madura foot (Mycetoma)** is a chronic, granulomatous, subcutaneous infection characterized by a clinical triad of **localized swelling, multiple interconnecting sinus tracts, and the discharge of grains.** It is caused by two distinct groups of organisms: **Eumycetoma** (fungal) and **Actinomycetoma** (filamentous bacteria). **Why Mucor is the correct answer:** **Mucor** is a member of the Zygomycetes family and causes **Mucormycosis**, an acute, aggressive, angioinvasive infection typically seen in immunocompromised patients or those with uncontrolled diabetes. It does not cause chronic granulomatous mycetoma or produce grains. **Analysis of other options:** * **Pseudallescheria boydii:** This is the most common cause of fungal mycetoma (**Eumycetoma**) worldwide. It typically produces white-to-yellow grains. * **Actinomycetes:** This is a broad group of filamentous, Gram-positive bacteria. **Actinomycetoma** accounts for the majority of cases in India (e.g., *Actinomadura madurae*). * **Nocardia:** Species like *Nocardia brasiliensis* are major causes of **Actinomycetoma**. They are partially acid-fast and produce fine, white-to-yellow grains. **High-Yield Clinical Pearls for NEET-PG:** * **The Grains:** The color of the grain can hint at the etiology. Black grains are always fungal (*Madurella mycetomatis*), while red grains are characteristic of *Actinomadura pelletieri*. * **Diagnosis:** The gold standard is the histopathological examination of the grain. * **Radiology:** The **"Dot-in-circle" sign** on MRI is a pathognomonic feature of mycetoma. * **Treatment:** Actinomycetoma responds well to antibiotics (Welsh regimen: Amikacin + Cotrimoxazole), whereas Eumycetoma often requires long-term antifungals (Itraconazole) and surgical debridement.

Q: A 40-year-old man presented with swelling over his foot with multiple sinus discharge. What is the likely diagnosis?

Madura mycosis. ***Madura mycosis*** - **Foot swelling** with **multiple sinus discharge** forms the classic triad of **mycetoma** (Madura foot), caused by fungal (**eumycetoma**) or bacterial (**actinomycetoma**) organisms. - The discharge typically contains **colored granules** (black for **Madurella mycetomatis**, white/yellow for **Nocardia** species) which are pathognomonic for this condition. *Acute myelitis* - Refers to **spinal cord inflammation** causing neurological deficits like **paraplegia** or **quadriplegia**, not foot swelling. - Presents with **motor weakness**, **sensory loss**, and **bladder dysfunction**, none of which match this clinical picture. *Chronic Osteomyelitis* - Typically presents with **single draining sinus** rather than multiple sinuses, and lacks the characteristic **granule discharge**. - More commonly affects **long bones** and is associated with **systemic symptoms** like fever and elevated inflammatory markers. *Dracunculosis* - Caused by **Dracunculus medinensis** (Guinea worm) presenting as a **single blister** with protruding worm, not multiple sinuses. - Endemic to specific regions in **Africa** and involves **contaminated water** consumption, with the worm emerging through skin after one year.

Q: Cigar-shaped yeast cells are seen with which of the following organisms?

S. schenkii. **Explanation:** The correct answer is **B. S. schenkii**. *Sporothrix schenckii* is a **dimorphic fungus**, meaning it exists as a mold in the environment (at 25°C) and as a yeast in human tissue (at 37°C). The characteristic morphological feature of the yeast phase in tissue or culture is the presence of **"cigar-shaped"** (elongated, fusiform) budding cells. This is a classic high-yield microscopic finding used to identify Sporotrichosis, often clinically associated with "Rose gardener’s disease." **Why the other options are incorrect:** * **C. albicans:** Typically presents as oval budding yeast cells with **pseudohyphae** and the ability to form true hyphae (germ tubes). * **H. capsulatum:** Appears as small, oval, **intracellular** yeast cells (often found within macrophages). They are not elongated or cigar-shaped. * **C. neoformans:** Characterized by round-to-oval yeast cells surrounded by a thick, **polysaccharide capsule**, best visualized with India Ink (negative staining). **High-Yield Clinical Pearls for NEET-PG:** 1. **Asteroid Bodies:** In tissue sections, *S. schenckii* may show a central yeast cell surrounded by eosinophilic radiating processes (Splendore-Hoeppli phenomenon). 2. **Clinical Presentation:** Typically presents as a linear chain of nodules following lymphatic drainage (**lymphocutaneous spread**) after traumatic inoculation (e.g., thorn prick). 3. **Drug of Choice:** **Itraconazole** is the preferred treatment. Historically, saturated solution of potassium iodide (SSKI) was used. 4. **Culture:** At 25°C, it produces "flowerette" or **daisy-like** arrangements of conidia.

Q: A man developed a pustule after being pricked by a thorn in the garden. Laboratory examination of the tissue specimen shows cigar-shaped budding yeasts. What is the most probable causative agent?

Sporothrix. **Explanation:** The clinical presentation and laboratory findings are classic for **Sporotrichosis**, caused by the dimorphic fungus **_Sporothrix schenckii_**. **1. Why the correct answer is right:** * **Mechanism of Injury:** The history of a "thorn prick" while gardening is a high-yield clinical clue for **Rose Gardener’s Disease**. The fungus is commonly found in soil, moss, and decaying vegetation. * **Morphology:** _Sporothrix_ is a **thermally dimorphic fungus**. In the tissue (at 37°C), it exists as yeast. The description of **"cigar-shaped" budding yeasts** is the pathognomonic histological feature for this organism. * **Clinical Progression:** It typically begins as a painless pustule or nodule at the site of inoculation, which may later ulcerate and spread along the draining lymphatics (nodular lymphangitis). **2. Why the incorrect options are wrong:** * **B. Sporotrichosis:** This is the name of the **disease**, not the causative agent. The question asks for the "causative agent," making _Sporothrix_ the more precise answer. * **C. Phialophora:** This is a genus of dematiaceous (pigmented) fungi that causes **Chromoblastomycosis**. Histology would show "copper-colored" sclerotic bodies (Medlar bodies), not cigar-shaped yeasts. * **D. Aspergillus:** This is a monomorphic mold characterized by septate hyphae with **acute-angle (45°) branching**. It does not form yeasts in tissue. **High-Yield Clinical Pearls for NEET-PG:** * **Asteroid Bodies:** In tissue, yeasts may be surrounded by eosinophilic material (Splendore-Hoeppli phenomenon), known as Asteroid bodies. * **Culture:** At 25°C, it grows as a mold with "flowerette" or "daisy-like" arrangements of conidia. * **Treatment:** The drug of choice is **Itraconazole**. Historically, saturated solution of potassium iodide (SSKI) was used.

Q: Penicillium marneffei is commonly associated with which of the following conditions?

Acquired Immunodeficiency Syndrome (AIDS). **Explanation:** *Penicillium marneffei* (now reclassified as ***Talaromyces marneffei***) is a unique **dimorphic fungus** that serves as a major opportunistic pathogen and a defining illness in patients with **Acquired Immunodeficiency Syndrome (AIDS)**, particularly in Southeast Asia (endemic in Thailand, Vietnam, and Southern China). **1. Why Option B is Correct:** In patients with advanced HIV/AIDS (typically with **CD4 counts <100 cells/μL**), *T. marneffei* causes a systemic infection involving the reticuloendothelial system. It is characterized by fever, weight loss, anemia, and distinctive **umbilicated skin lesions** (resembling *Molluscum contagiosum*). The fungus is intracellular, often seen within macrophages, mimicking *Histoplasma capsulatum*. **2. Why Other Options are Incorrect:** * **A. Tuberculosis:** While TB is the most common opportunistic infection in HIV, *T. marneffei* is a fungal pathogen, not a mycobacterial one. They may co-exist, but the fungus is not "associated" with TB itself. * **C. Diabetes Mellitus:** DM is strongly associated with **Mucormycosis** (Zygomycosis) and *Candida* infections, but not specifically with *T. marneffei*. * **D. Kala-azar:** Caused by *Leishmania donovani*, it presents with similar hepatosplenomegaly, but it is a protozoal disease. **Clinical Pearls for NEET-PG:** * **Dimorphism:** It is the only *Penicillium* species that is thermally dimorphic (Mould at 25°C; Yeast at 37°C). * **Laboratory Hallmark:** On Sabouraud Dextrose Agar (SDA) at 25°C, it produces a characteristic **diffusible red pigment**. * **Microscopy:** Yeast cells divide by **fission** (transverse septum), not budding. * **Treatment:** Intravenous Amphotericin B followed by oral Itraconazole.

Question 1

Sulphur granules are composed of?

Accepted Answer

Fungal filaments

Answer

Leukocytes

Answer

Erythrocytes

Answer

Keratinocytes

Question 2

Homosexual men with AIDS are most likely to exhibit which of the following conditions?

Accepted Answer

Pneumocystis pneumonia

Answer

Antibodies to Human T-lymphotropic virus type II (HTLV-II)

Answer

Elevation of inducer/helper T cells

Answer

All of the above

Question 3

A female presented with thick white discharge and pruritus. What is the etiological agent?

Accepted Answer

Candida

Answer

Gardnerella

Answer

Trichomonas vaginalis

Answer

Gonococci

Question 4

Which of the following organisms cannot be cultured?

Accepted Answer

Pneumocystis jiroveci

Answer

Klebsiella rhinoscleromatis

Answer

Klebsiella ozaenae

Answer

Klebsiella granulomatis

Question 5

A 38-year-old AIDS patient presents with a one-week history of fever and increasing headache. He also reports photophobia, nausea, and weakness. His past medical history is significant for Pneumocystis pneumonia, and his CD4 count is 89. Current medications include trimethoprim/sulfamethoxazole and indinavir. Cerebrospinal fluid (CSF) analysis reveals 4 WBCs, and budding encapsulated yeast forms grow on Sabouraud's agar. What is the accurate description of the morphology of the infectious form of the organism responsible for this patient's illness?

Accepted Answer

Encapsulated budding yeasts

Answer

Broad-based, budding yeasts

Answer

Budding yeasts in a pseudohyphae

Answer

Cylindrical arthroconidia

Question 6

Which of the following is NOT a cause of Madura foot?

Accepted Answer

Mucor

Answer

Pseudallescheria

Answer

Actinomycetes

Answer

Nocardia

Question 7

A 40-year-old man presented with swelling over his foot with multiple sinus discharge. What is the likely diagnosis?

Accepted Answer

Madura mycosis

Answer

Acute myelitis

Answer

Chronic Osteomyelitis

Answer

Dracunculosis

Question 8

Cigar-shaped yeast cells are seen with which of the following organisms?

Accepted Answer

S. schenkii

Answer

C. albicans

Answer

H. capsulatum

Answer

C. neoformans

Question 9

A man developed a pustule after being pricked by a thorn in the garden. Laboratory examination of the tissue specimen shows cigar-shaped budding yeasts. What is the most probable causative agent?

Accepted Answer

Sporothrix

Answer

Sporotrichosis

Answer

Phialophora

Answer

Aspergillus

Question 10

Penicillium marneffei is commonly associated with which of the following conditions?

Accepted Answer

Acquired Immunodeficiency Syndrome (AIDS)

Answer

Tuberculosis

Answer

Diabetes Mellitus

Answer

Kala-azar

Mycology — MCQs

Mycology — MCQs

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