Immunodeficiency Disorders — MCQs
Which of the following disorders presents with repeated catalase positive infections?
In which of the following disorders, vaccines are not contraindicated in the person suffering from that disease?
Which of the following is not found in DiGeorge's syndrome?
A 35-year-old male presents with fever, night sweats, and unintentional weight loss over the past 3 months. He has a history of intravenous drug use. Most appropriate next step in the diagnosis?
Brain abscess in immunodeficient person is due to :
A 24-year-old patient presents with a high-grade fever, headache, and weakness since 5 days. He gives a history of blood transfusion 4 months back. The microscopic examination of the thin blood smear is given below. What is the most probable causative agent?
Which of the following is the aetiological agent most often associated with Epiglottitis in children -
Periventricular calcification seen in encephalitis is due to -
Botryomycosis is a ___ disease
Which is the most immunogenic antigen of Salmonella Typhi?
Immunodeficiency Disorders Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following disorders presents with repeated catalase positive infections?
- A. Chediak higashi syndrome
- B. SCID
- C. X linked hypogammaglobulinemia
- D. CGD (Correct Answer)
Explanation: ***CGD*** - Chronic Granulomatous Disease (CGD) is characterized by a defect in **NADPH oxidase**, preventing phagocytes from producing a **respiratory burst** to kill certain bacteria and fungi. - Patients with CGD are particularly susceptible to infections by **catalase-positive organisms** because these organisms degrade hydrogen peroxide, which CGD phagocytes rely on for killing. *Chediak higashi syndrome* - This syndrome involves defective lysosomal trafficking, leading to impaired neutrophil chemotaxis and degranulation, resulting in recurrent infections, but not specifically to **catalase-positive organisms**. - Other features include **partial albinism**, peripheral neuropathy, and normal respiratory burst. *SCID* - Severe Combined Immunodeficiency (SCID) involves a profound defect in both **T-cell and B-cell immunity**, leading to severe and recurrent infections by a wide range of pathogens, not limited to catalase-positive ones [1]. - Patients typically present in infancy with **failure to thrive**, opportunistic infections, and lack of lymphoid tissue [1]. *X linked hypogammaglobulinemia* - Also known as **Bruton's agammaglobulinemia**, this disorder involves a defect in B-cell maturation, leading to the absence of antibodies and recurrent bacterial infections [1]. - The infections are typically with **encapsulated bacteria** and are not specifically linked to catalase-positive organisms [1].
Question 2: In which of the following disorders, vaccines are not contraindicated in the person suffering from that disease?
- A. Digeorge syndrome
- B. Wiskott Aldrich syndrome
- C. Ataxia telangiectasia
- D. Complement deficiency disorders (Correct Answer)
Explanation: ***Complement deficiency disorders*** - While patients with **complement deficiencies** are susceptible to certain infections (especially by encapsulated bacteria), their adaptive immune system is generally intact. - Therefore, most vaccines, including **live attenuated vaccines**, are not contraindicated; in fact, vaccination is crucial for preventing infections in these patients. *Digeorge syndrome* - This syndrome involves **thymic hypoplasia or aplasia**, leading to severe **T-cell immunodeficiency**. - **Live attenuated vaccines** (e.g., MMR, varicella) are contraindicated due to the risk of uncontrolled replication of the vaccine strain in immunocompromised individuals. *Wiskott Aldrich syndrome* - This is an **X-linked immunodeficiency** characterized by immunodeficiency, eczema, and thrombocytopenia, involving defects in both T and B cell function, and **platelet dysfunction**. - Due to profound immune defects, particularly in T-cell function, **live attenuated vaccines** are contraindicated. *Ataxia telangiectasia* - This is an autosomal recessive disorder causing **progressive cerebellar ataxia**, telangiectasias, and severe **combined immunodeficiency (SCID)-like features** affecting both T and B cells, as well as an increased risk of malignancy. - Due to the severe immunodeficiency, **live attenuated vaccines** are contraindicated.
Question 3: Which of the following is not found in DiGeorge's syndrome?
- A. Eczema (Correct Answer)
- B. Tetany
- C. T cell lymphopenia
- D. Mucocutaneous candidiasis
Explanation: ***Eczema*** - **Eczema** is NOT a recognized feature of **DiGeorge syndrome** (22q11.2 deletion syndrome). - While individuals with immunodeficiencies may experience various skin conditions, eczema is specifically associated with conditions like **Hyper-IgE syndrome, Wiskott-Aldrich syndrome**, or atopic disorders, not DiGeorge's. - DiGeorge's follows the **CATCH-22 mnemonic**: Cardiac defects, Abnormal facies, Thymic hypoplasia, Cleft palate, Hypocalcemia, 22q11 deletion. *Tetany* - **Tetany IS found** in DiGeorge's syndrome due to **hypocalcemia** from parathyroid gland hypoplasia or aplasia. - The lack of parathyroid hormone leads to **low serum calcium levels**, resulting in increased neuromuscular excitability and tetany. *T cell lymphopenia* - **T-cell lymphopenia IS found** in DiGeorge's syndrome due to **thymic hypoplasia or aplasia**. - The primary immunological defect is **T-cell deficiency**, leading to increased susceptibility to viral, fungal, and intracellular bacterial infections. - B-cell numbers are typically normal, though antibody responses may be impaired due to lack of T-cell help. *Mucocutaneous candidiasis* - **This IS found** in patients with DiGeorge's syndrome as an opportunistic infection due to **T-cell immunodeficiency**. - The impaired **cellular immunity** makes individuals highly susceptible to fungal infections like *Candida albicans* affecting mucous membranes and skin.
Question 4: A 35-year-old male presents with fever, night sweats, and unintentional weight loss over the past 3 months. He has a history of intravenous drug use. Most appropriate next step in the diagnosis?
- A. HIV test (Correct Answer)
- B. Chest X-ray
- C. Tuberculin skin test
- D. Blood culture
Explanation: ***HIV test*** - The patient's **risk factors** (intravenous drug use) and constitutional symptoms (fever, night sweats, unintentional weight loss) are highly suggestive of **HIV infection**, [2], [5] which can lead to opportunistic infections or directly cause these symptoms. - An HIV test is crucial for **early diagnosis** and management to prevent progression to AIDS and initiate highly active antiretroviral therapy (HAART) [4]. *Chest X-ray* - While a Chest X-ray can detect pulmonary infections often associated with immunosuppression, it is a **secondary investigation** and not the most appropriate initial diagnostic step for the underlying cause of immunosuppression. - It would be more useful after identifying an underlying condition like HIV, especially if respiratory symptoms were prominent. *Tuberculin skin test* - Tuberculosis is a common opportunistic infection in immunocompromised individuals, including those with HIV, and can present with these symptoms [1]. - However, performing a **Tuberculin skin test** or **IGRA** is typically done after initial screening for HIV, as the interpretation relies on the patient's immune status. *Blood culture* - Blood cultures are useful for detecting **bacteremia or fungemia** and can help identify specific infections [3]. - While relevant for fever and night sweats, they are a **specific diagnostic test** for active bloodstream infection and do not address the underlying systemic cause of immunosuppression and constitutional symptoms like HIV.
Question 5: 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 6: A 24-year-old patient presents with a high-grade fever, headache, and weakness since 5 days. He gives a history of blood transfusion 4 months back. The microscopic examination of the thin blood smear is given below. What is the most probable causative agent?
- A. Leishmania donovani
- B. Plasmodium vivax
- C. Plasmodium falciparum
- D. Babesia microti (Correct Answer)
Explanation: ***Babesia microti*** - The image displays **intraerythrocytic pleomorphic ring forms** and classic **tetrad formations (Maltese cross)**, which are pathognomonic for **Babesia microti** infection. - The patient's history of **blood transfusion** 4 months prior is highly suggestive, as babesiosis can be transmitted through contaminated blood products with an incubation period fitting this timeline. - Clinical features include high-grade fever, headache, and weakness, consistent with babesiosis. *Leishmania donovani* - This parasite exists as **amastigotes within macrophages** and does not infect red blood cells or form ring structures as seen in the image. - While it causes fever and weakness (**visceral leishmaniasis/kala-azar**), its microscopic appearance on blood smear shows amastigotes in macrophages, not intraerythrocytic forms. *Plasmodium vivax* - While *P. vivax* infects red blood cells and forms ring stages, it is typically characterized by **enlarged infected RBCs with Schüffner's dots**, which are not seen here. - The **tetrad formations (Maltese cross)** seen in the image are pathognomonic for Babesia, not Plasmodium species. *Plasmodium falciparum* - This parasite typically presents with **multiple small ring forms per RBC** and **applique or "accole" forms** at the periphery of red blood cells. - While *P. falciparum* can cause high fever and severe disease, the specific **tetrad configuration (Maltese cross)** is characteristic of Babesia, not Plasmodium.
Question 7: Which of the following is the aetiological agent most often associated with Epiglottitis in children -
- A. Neisseria sp
- B. Moraxella catarrhalis
- C. Haemophilus influenzae type b (Correct Answer)
- D. Streptococcus pneumoniae
Explanation: ***Haemophilus influenzae type b*** - Historically, **_Haemophilus influenzae_ type b (Hib)** was the most common cause of **epiglottitis** in children. - The introduction of the **Hib vaccine** has significantly reduced its incidence, but it remains a crucial consideration. *Neisseria sp* - **_Neisseria_ species** are typically associated with infections like **meningitis** and **gonorrhea**, not primary causes of epiglottitis. - While **_Neisseria meningitidis_** can cause invasive disease, it's not a common pathogen for epiglottitis. *Moraxella catarrhalis* - **_Moraxella catarrhalis_** is a common cause of **otitis media**, **sinusitis**, and **bronchitis**, especially in children. - It is not a principal cause of acute epiglottitis. *Streptococcus pneumoniae* - **_Streptococcus pneumoniae_** is a major cause of **pneumonia**, **otitis media**, **meningitis**, and **sepsis**. - While it can cause respiratory infections, it is not the most frequent pathogen associated with epiglottitis compared to Hib pre-vaccine era.
Question 8: Periventricular calcification seen in encephalitis is due to -
- A. HSV-I
- B. HSV-II
- C. CMV (Correct Answer)
- D. Herpes Zoster
Explanation: ***CMV*** - **Cytomegalovirus (CMV)** encephalitis, particularly in congenitally infected infants, is classically associated with **periventricular calcifications** due to its destructive effect on neural progenitors around the ventricles. - CMV has an **affinity for immature brain tissue**, leading to inflammation, necrosis, and subsequent calcification in these areas. *HSV-I* - **Herpes Simplex Virus type 1 (HSV-1)** encephalitis typically causes focal lesions, often involving the **temporal and frontal lobes**, and is characterized by neuronal necrosis and hemorrhage, not usually periventricular calcifications. - It does not have the same tropism for the germinal matrix responsible for periventricular calcifications as CMV. *HSV-II* - **Herpes Simplex Virus type 2 (HSV-2)** encephalitis can occur in neonates, usually presenting as a disseminated infection or meningitis/encephalitis. While it can cause significant brain damage, **periventricular calcifications are not its hallmark feature**; hydrocephalus or white matter injury may be seen. - HSV-2 tends to cause a more diffuse inflammatory response rather than the localized damage leading to periventricular calcifications. *Herpes Zoster* - **Varicella-zoster virus (VZV)**, which causes herpes zoster, can lead to encephalitis, particularly in immunocompromised individuals. This often presents as **vasculopathy**, stroke, or focal neurological deficits, typically *without* periventricular calcifications. - VZV encephalitis usually involves inflammation of blood vessels and parenchyma but does not target the periventricular region in a way that causes characteristic calcifications.
Question 9: Botryomycosis is a ___ disease
- A. Viral
- B. Bacterial (Correct Answer)
- C. Parasitic
- D. Fungal
Explanation: ***Bacterial*** - **Botryomycosis** is primarily a **bacterial infection**, commonly caused by *Staphylococcus aureus* or, less frequently, by gram-negative bacteria like *Pseudomonas aeruginosa*. - It presents as chronic suppurative granulomatous inflammation characterized by the presence of **"grains" or "granules"** composed of bacterial microcolonies surrounded by hyaline material. *Viral* - **Viral infections** are caused by viruses and are typically characterized by intracellular replication and various cytopathic effects. - Botryomycosis does not involve viral pathogens; its pathogenesis is entirely distinct from viral diseases. *Parasitic* - **Parasitic diseases** are caused by parasites such as protozoa, helminths, or ectoparasites. - The clinical and pathological features of botryomycosis, including the distinct bacterial grains, do not align with parasitic infections. *Fungal* - Although it can superficially resemble **mycetoma (a fungal infection)** due to the presence of "grains," botryomycosis is not caused by fungi. - Mycetoma involves fungal organisms like *Madurella mycetomatis* or *Actinomadura madura*, which are distinctly different from the bacterial agents of botryomycosis.
Question 10: Which is the most immunogenic antigen of Salmonella Typhi?
- A. O antigen
- B. H antigen (Correct Answer)
- C. Vi antigen
- D. Somatic antigen
Explanation: **Explanation:** The immunogenicity of an antigen is determined by its chemical complexity and size. In *Salmonella Typhi*, the **H (Flagellar) antigen** is the most immunogenic because it is composed of proteins (flagellin). Proteins are more potent triggers of the immune system compared to polysaccharides, leading to a robust antibody response. This is why H-agglutinins appear earlier and reach higher titers than O-agglutinins during a *Salmonella* infection. **Analysis of Options:** * **A & D. O Antigen (Somatic Antigen):** These are the same entity. The O antigen is a lipopolysaccharide (LPS) located on the outer membrane. While it is important for serogrouping, polysaccharides are generally less immunogenic than proteins. O-antibodies appear later and disappear sooner than H-antibodies. * **C. Vi Antigen:** This is a surface polysaccharide capsular antigen (Virulence antigen). It is poorly immunogenic and primarily functions by masking the O antigen from antibodies. Its main clinical utility is in identifying chronic carriers and for use in certain vaccines (e.g., Typhim VI). **High-Yield Clinical Pearls for NEET-PG:** * **Widal Test:** Measures antibodies against O and H antigens. A titer of **>1:160 for O** and **>1:160 for H** is usually considered significant in endemic areas. * **Sequence of Appearance:** In Enteric fever, O antibodies appear first (around the end of the 1st week), but H antibodies reach higher peaks and persist longer. * **Carrier State:** Persistent high titers of **Vi antibodies** (1:10 or more) suggest a chronic carrier state, as the bacteria continue to harbor the capsule in the gallbladder or urinary tract.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free