Cryptococcosis — MCQs
A patient with AIDS presents with meningitis. India ink staining shows encapsulated yeasts. Which organism is most likely?
Eosinophilic meningitis is seen with all except:
Which of the following is NOT a virulence factor of Cryptococcus?
Most serious characteristic finding of HIV in children is?
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?
Which of the following is the most common yeast pathogen?
All are correct about the image shown except:
Brain abscess in immunodeficient person is due to :
After 5 days of birth, a baby developed poor feeding, convulsions, fever, high protein, low sugar, and low chloride levels in the cerebrospinal fluid. This is most likely due to what?
Which statement is false regarding Cryptococcus neoformans?
Cryptococcosis Indian Medical PG Practice Questions and MCQs
Question 1: A patient with AIDS presents with meningitis. India ink staining shows encapsulated yeasts. Which organism is most likely?
- A. Candida albicans
- B. Cryptococcus neoformans (Correct Answer)
- C. Histoplasma capsulatum
- D. Coccidioides immitis
Explanation: ***Cryptococcus neoformans*** - This fungus is a common cause of **meningitis in AIDS patients** and characteristically appears as **encapsulated yeasts** on India ink staining of CSF. - The capsule excludes the ink, creating a distinct **halo** around the yeast cell, which is diagnostic. *Candida albicans* - While *Candida* can cause systemic infections, including meningitis, it typically presents as **pseudohyphae** or budding yeast without an obvious capsule on India ink stain. - *Candida meningitis* is less common in AIDS patients compared to *Cryptococcus*. *Histoplasma capsulatum* - This is a dimorphic fungus that causes **histoplasmosis**, often disseminated in AIDS patients, but typically manifests as **pulmonary disease** or hepatosplenomegaly. - It appears as small, **intracellular yeasts** within macrophages and would not show an encapsulated form on India ink stain in CSF. *Coccidioides immitis* - This dimorphic fungus causes **coccidioidomycosis**, which can lead to meningitis, particularly in immunocompromised individuals. - In CSF, it is seen as **spherules containing endospores**, not encapsulated yeasts, which is a distinct morphological feature.
Question 2: Eosinophilic meningitis is seen with all except:
- A. Cryptococcal meningitis (Correct Answer)
- B. Coccidioidomycosis
- C. Helminthic infections
- D. Leptomeningeal metastasis
Explanation: ***Cryptococcal meningitis*** - This is a **fungal infection** that typically causes a **lymphocytic or monocytic pleocytosis** in the cerebrospinal fluid (CSF), not eosinophilic meningitis. - While it can occur in immunocompromised individuals, **eosinophilia in the CSF** is not a characteristic feature. *Coccidioidomycosis* - This **fungal infection** can cause meningitis with a notable **eosinophilic pleocytosis** in the CSF [1]. - It is known to produce a chronic meningitis that may present with CSF eosinophilia. *Helminthic infections* - **Parasitic infections** like **Strongyloides, Gnathostoma, and Angiostrongylus cantonensis** are well-known causes of eosinophilic meningitis [2]. - The host immune response to these parasites often involves a strong **eosinophilic infiltrate** [2]. *Leptomeningeal metastasis* - **Leptomeningeal carcinomatosis** (metastasis) can cause a variety of CSF findings, including an **eosinophilic pleocytosis** [3]. - This is particularly true for certain types of cancers like **lymphoma** or **small cell lung cancer**.
Question 3: Which of the following is NOT a virulence factor of Cryptococcus?
- A. Polysaccharide capsule
- B. Ability to make melanin
- C. Production of protease (Correct Answer)
- D. Urease production
Explanation: ***Production of protease*** - While *Cryptococcus neoformans* can produce some proteolytic enzymes, **protease production is not considered a major or classical virulence factor** in standard medical microbiology literature. - Unlike the other three factors listed, proteases are not prominently featured as key virulence mechanisms in *Cryptococcus* pathogenesis for medical education purposes. - The primary virulence factors emphasized for *Cryptococcus* are the capsule, melanin, and urease. *Polysaccharide capsule* - The **polysaccharide capsule** is the MOST important virulence factor, protecting the yeast from phagocytosis and immune clearance. - It interferes with antigen presentation, antibody binding, and complement activation, making it crucial for survival in the host. *Ability to make melanin* - **Melanin production** protects *Cryptococcus* from oxidative stress, free radicals, UV radiation, and antifungal agents. - It contributes to survival in macrophages and persistence in the central nervous system. *Urease production* - **Urease production** enables *Cryptococcus* to cross the blood-brain barrier and colonize the central nervous system. - Urease hydrolyzes urea into ammonia, causing local alkalinization that facilitates CNS invasion and contributes to meningoencephalitis.
Question 4: Most serious characteristic finding of HIV in children is?
- A. Kaposi sarcoma is common
- B. Cryptococcal diarrhoea is common
- C. Recurrent chest infection (Correct Answer)
- D. Recurrent candidiasis
Explanation: ***Recurrent chest infection*** - **Recurrent chest infections**, particularly with common bacterial pathogens, are a hallmark of HIV in children due to their underdeveloped immune systems being further compromised. - Children with HIV are highly susceptible to respiratory infections such as **pneumonia** and **bronchiolitis**, leading to frequent hospitalizations and poor outcomes. *Kaposi sarcoma is common* - **Kaposi sarcoma** is a well-known HIV-associated malignancy, but it is much more prevalent in **HIV-positive adults**, especially men who have sex with men, rather than in children. - While it can occur in children, it is not considered a *characteristic* or common presenting feature, as other opportunistic infections and non-specific symptoms are far more frequent. *Cryptococcal diarrhoea is common* - **Cryptococcal infection** primarily manifests as **meningitis** or disseminated disease, particularly in adults with advanced HIV. - While gastrointestinal symptoms can occur, **Cryptococcal diarrhea** is not a common or characteristic presentation of HIV in children. *Recurrent candidiasis* - While **recurrent oral candidiasis** (thrush) is common in HIV-infected children, it is often one of the **earliest indicators** and can be present even in less advanced disease. - However, **recurrent chest infections** generally represent a more significant and debilitating manifestation of immune compromise in pediatric HIV.
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)
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.
Question 6: Which of the following is the most common yeast pathogen?
- A. Candida (Correct Answer)
- B. Mucor
- C. Rhizopus
- D. Cryptococcus
Explanation: ***Candida*** - **Candida** species, particularly *Candida albicans*, are the **most common cause of fungal infections** worldwide, ranging from superficial mucocutaneous infections to invasive systemic candidiasis. - They are part of the normal human microbiota and opportunistic pathogens, thriving in conditions like **immunocompromise**, antibiotic use, or presence of medical devices. *Mucor* - **Mucor** is a genus of mold, not yeast, and is known to cause **mucormycosis**, a severe and rapidly progressive fungal infection. - While dangerous, mucormycosis is **much rarer** compared to candidiasis. *Rhizopus* - **Rhizopus** is also a genus of mold, not yeast, and is another causative agent of **mucormycosis**, particularly in immunocompromised individuals. - Like Mucor, infections caused by Rhizopus are **less common** than those caused by Candida. *Cryptococcus* - **Cryptococcus neoformans** is a significant yeast pathogen, primarily causing **cryptococcosis**, which often manifests as meningoencephalitis in immunocompromised patients. - Although it is an important pathogen, its overall incidence is **lower than that of Candida** species.
Question 7: All are correct about the image shown except:
- A. Cryptococcus neoformans
- B. Primary site of infection is CNS (Correct Answer)
- C. Thick polysaccharide capsule
- D. Mucicarmine stain can be used
Explanation: ***Primary site of infection is CNS*** - While *Cryptococcus neoformans* is well-known for causing **meningitis** (a CNS infection), the **primary site of infection** is typically the **lungs**, acquired through inhalation of spores. Dissemination to the CNS occurs subsequently, especially in immunocompromised individuals. *Cryptococcus neoformans* - The image, showing encapsulated yeast cells with varying sizes and budding, is characteristic of **Cryptococcus neoformans** under India ink stain, where the capsule excludes the ink, creating a halo effect. - This fungus is known for its distinctive **thick polysaccharide capsule** and its tendency to be found in environments contaminated with bird droppings. *Thick polysaccharide capsule* - The clear halo around the yeast cells in the image directly demonstrates the presence of a **thick polysaccharide capsule**, which is a key virulence factor distinguishing *Cryptococcus neoformans*. - This capsule is responsible for the organism's unique appearance in **India ink preparations** and plays a crucial role in immune evasion. *Mucicarmine stain can be used* - The **mucicarmine stain** specifically stains the **polysaccharide capsule** of *Cryptococcus neoformans* bright red, aiding in its identification in tissue samples. - This stain is a valuable diagnostic tool, particularly when dealing with tissue biopsies where the capsule might not be as distinctly visible with India ink due to cellular debris.
Question 8: Brain abscess in immunodeficient person is due to :
- A. Aspergillus
- B. Toxoplasma gondii (Correct Answer)
- C. Cryptococcus
- D. Candida
Explanation: ***Toxoplasma gondii*** - **Toxoplasma gondii** is a very common cause of **brain abscesses** (cerebral toxoplasmosis) in individuals with compromised immune systems, especially those with AIDS. - The parasite is usually latent in many people and reactivates when the immune system weakens. *Aspergillus* - While *Aspergillus* can cause central nervous system infections, including brain abscesses, this is usually seen in severely **neutropenic** or transplant patients. - *Aspergillus* typically invades via **hematogenous spread** from a primary pulmonary infection or directly from sinusitis. *Cryptococcus* - *Cryptococcus neoformans* is a significant cause of **meningitis** in immunocompromised patients, particularly those with HIV/AIDS. - While it can cause **cryptococcomas** (focal lesions), pure abscess formation is less common than with *Toxoplasma*. *Candida* - *Candida* species can cause **brain microabscesses** or multifocal lesions, especially in patients with disseminated candidiasis originating from prolonged hospitalization or indwelling catheters. - However, large, solitary brain abscesses are less typical for *Candida* compared to *Toxoplasma gondii*.
Question 9: After 5 days of birth, a baby developed poor feeding, convulsions, fever, high protein, low sugar, and low chloride levels in the cerebrospinal fluid. This is most likely due to what?
- A. Listeria monocytogenes infection (Correct Answer)
- B. Tuberculosis infection
- C. Leptospira infection
- D. Mycoplasma pneumoniae infection
Explanation: ***Listeria monocytogenes infection*** - **Listeria meningitis** in neonates often presents with non-specific symptoms such as **poor feeding**, **convulsions**, and fever, typically in the **first week of life**. - The CSF profile of **high protein**, **low glucose**, and **low chloride** is characteristic of **bacterial meningitis**, which *Listeria* commonly causes in newborns. - *Listeria* is one of the leading causes of neonatal meningitis, particularly in early-onset sepsis (within 7 days of birth). *Tuberculosis infection* - **Tuberculous meningitis** typically has a more insidious onset and is less common in neonates unless there's significant maternal exposure. - While it can cause low glucose and high protein in CSF, the acute presentation in a 5-day-old neonate is atypical for TB. - TB meningitis has a longer incubation period and wouldn't typically present this early. *Leptospira infection* - **Leptospirosis** is rare in neonates and usually presents with symptoms like fever, headache, and muscle pain, sometimes leading to renal or hepatic involvement. - The CSF profile in leptospirosis would typically show **lymphocytic pleocytosis** with normal or slightly elevated protein, not the classic bacterial meningitis pattern. *Mycoplasma pneumoniae infection* - **Mycoplasma pneumoniae** is primarily a cause of **respiratory infections** (e.g., atypical pneumonia) in older children and adults. - It rarely causes meningitis in neonates, and neonatal infection is highly unusual. - When CNS involvement occurs, it's typically in older children with preceding respiratory symptoms.
Question 10: Which statement is false regarding Cryptococcus neoformans?
- A. Grows at 5°C and 37°C
- B. Has 4 serotypes
- C. Urease negative (Correct Answer)
- D. Causes superficial skin infection
Explanation: **Explanation:** *Cryptococcus neoformans* is an encapsulated yeast primarily associated with pigeon droppings and is a significant opportunistic pathogen in immunocompromised patients (e.g., HIV/AIDS). **1. Why "Urease negative" is the False Statement:** *Cryptococcus neoformans* is characteristically **Urease positive**. The production of the urease enzyme is a key biochemical marker used in the laboratory to differentiate it from other yeasts like *Candida albicans* (which is urease negative). It hydrolyzes urea to produce ammonia, raising the pH and changing the indicator color. **2. Analysis of Other Options:** * **Option A (Grows at 5°C and 37°C):** This is true. Unlike many other pathogenic fungi, *C. neoformans* can grow at 37°C (essential for human pathogenicity) and also at lower temperatures like 4°C–5°C. * **Option B (Has 4 serotypes):** This is true. Based on capsular polysaccharide antigens, it is classified into four serotypes: **A, B, C, and D**. (Note: Serotype A is *C. neoformans var. grubii*, while B and C are now often classified as *C. gattii*). * **Option D (Causes superficial skin infection):** This is true. While meningitis is the most common presentation, primary or secondary cutaneous cryptococcosis can occur, presenting as papules, pustules, or ulcerations. **High-Yield Clinical Pearls for NEET-PG:** * **Virulence Factor:** The **Polysaccharide capsule** (Glucuronoxylomannan) is the most important; it inhibits phagocytosis. * **Staining:** **India Ink** preparation shows a "halo" (negative staining). **Mucicarmine** stains the capsule red. * **Culture:** Grows on **Bird Seed Agar** (Niger Seed Agar) producing brown/black colonies due to **Phenoloxidase** activity (melanin production). * **Drug of Choice:** Induction with Amphotericin B + Flucytosine, followed by Fluconazole.
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