Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 1131: A 45-year-old man presents with a clean minor wound from gardening. His vaccination record shows he completed primary tetanus immunization series in childhood and received his last tetanus booster 12 years ago. What is the next step in management?

A. No further management required.
B. Single-dose Tetanus toxoid (TT) vaccine (Correct Answer)
C. Tetanus Immunoglobulin (TIG) with TT booster.
D. Complete tetanus vaccination series.

Explanation: **Single-dose Tetanus toxoid (TT) vaccine** - For a **clean, minor wound** in a patient who has completed their primary series but received their last booster 12 years ago, a single dose of **tetanus toxoid (TT)** or **TDaP** is indicated [1]. - Booster doses are recommended every **10 years** for tetanus-diphtheria protection. *Tetanus Immunoglobulin (TIG) with TT booster.* - **Tetanus Immunoglobulin (TIG)** is typically reserved for **dirty or contaminated wounds**, or for individuals with an **uncertain or incomplete vaccination history**, which is not the case here. - Giving TIG for a clean wound with a complete primary series would be over-treatment and unnecessary. *No further management required.* - The patient's last booster was **12 years ago**, exceeding the recommended 10-year interval for tetanus protection. - This makes him susceptible to tetanus, even from a clean wound, so **further management is required** [1]. *Complete tetanus vaccination series.* - A **complete tetanus vaccination series** is only needed for individuals who have an **incomplete or unknown** primary vaccination history. - This patient has a documented history of a completed primary series, so only a booster dose is required.

Question 1132: A bone marrow transplant recipient patient developed a chest infection. On HRCT, a 'tree-in-bud' appearance is seen. The most likely causative agent is:

A. Pneumocystis
B. TB (Correct Answer)
C. Klebsiella
D. RSV

Explanation: ***TB*** - A **'tree-in-bud' pattern** on HRCT is highly characteristic of **bronchiolar impaction** due to infection, classically seen in active **tuberculosis**. [1] - In an immunocompromised patient like a **bone marrow transplant recipient**, TB can rapidly disseminate and present with such radiographic findings. *Klebsiella* - **Klebsiella pneumonia** typically causes a **lobar pneumonia** with characteristic **bulging fissures** and severe consolidation. - It does not commonly present with a **'tree-in-bud' pattern** but rather extensive alveolar involvement. *Pneumocystis* - **Pneumocystis jirovecii pneumonia (PJP)** often presents with **diffuse ground-glass opacities** and **interstitial infiltrates**, predominantly in the perihilar region. [1] - A **'tree-in-bud' pattern** is not a typical radiographic feature of PJP. [1] *RSV* - **Respiratory Syncytial Virus (RSV)** typically causes **bronchiolitis** and **pneumonia**, especially in young children and immunocompromised adults. - While it can cause airway inflammation, a distinct **'tree-in-bud' pattern** is not its hallmark; rather, it often shows **peribronchial thickening** and **mucous plugging**.

Question 1133: Which viral infection is known to resemble the clinical features of erythroblastosis?

A. Cytomegalovirus (CMV)
B. Parvovirus B19 (Correct Answer)
C. Epstein-Barr Virus (EBV)
D. Herpes Simplex Virus (HSV)

Explanation: **Parvovirus B19** - Parvovirus B19 preferentially infects and destroys **erythroid progenitor cells** in the bone marrow, leading to varying degrees of anemia [1]. - In a fetus, this can manifest as **hydrops fetalis**, severe anemia, and **heart failure**, mirroring the severe hemolytic anemia seen in erythroblastosis fetalis caused by Rh incompatibility. *Epstein-Barr Virus (EBV)* - While EBV can cause various hematologic complications, it is not known to directly mimic the severe **erythroid aplasia** or hydrops fetalis associated with erythroblastosis. - EBV is primarily associated with **infectious mononucleosis**, which involves atypical lymphocytes and mild anemia, not destruction of red cell precursors. *Cytomegalovirus (CMV)* - CMV can cause **congenital infections** with a wide range of manifestations, including microcephaly, sensorineural hearing loss, and hepatosplenomegaly. - Although CMV can cause **anemia**, it does not typically cause the profound **erythroid aplasia** or hydrops that specifically resembles erythroblastosis. *Herpes Simplex Virus (HSV)* - HSV infection in neonates can cause severe disseminated disease, **encephalitis**, or localized skin, eye, and mouth disease. - HSV does not primarily target **erythroid precursors** or cause significant hemolytic anemia that would mimic erythroblastosis.

Question 1134: Following are the features of neuropathy associated with varicella-zoster infection, which of the following is true?

A. Shingles are distributed along sensory dermatomes. (Correct Answer)
B. Upon reactivation, the virus is transported along sensory nerves to the skin, causing neuropathic symptoms.
C. Intranuclear inclusions, a hallmark of herpesvirus infections, are found in the peripheral nervous system during VZV neuropathy.
D. Persistent infection in neurons of sensory ganglia is a key feature of varicella-zoster virus pathophysiology.

Explanation: ***Shingles are distributed along sensory dermatomes.*** [1] - This is a hallmark feature of **herpes zoster**, where the characteristic **vesicular rash** and pain follow the distribution of a single or several adjacent **dermatomes**. [1] - The virus reactivates in the **sensory ganglia** and travels down the sensory nerve to the skin, causing symptoms in the area supplied by that nerve. [1] *Upon reactivation, the virus is transported along sensory nerves to the skin, causing neuropathic symptoms.* - While the virus is transported along **sensory nerves** to the skin upon reactivation, this option is less encompassing as it only mentions neuropathic symptoms and doesn't specify the classic **dermatomal distribution** of the disease. - The primary manifestation is the characteristic **rash** and pain in a specific dermatome, not just "neuropathic symptoms" in general. [1] *Intranuclear inclusions, a hallmark of herpesvirus infections, are found in the peripheral nervous system during VZV neuropathy.* - While **intranuclear inclusions** (e.g., Cowdry type A) are indeed a hallmark of **herpesvirus infections**, they are typically found in infected cells such as **keratinocytes** in the skin lesions or neurons in the ganglia, not predominantly "in the peripheral nervous system" as a general finding for VZV neuropathy. - The presence of these inclusions is a microscopic finding of infected cells rather than a defining feature of the neuropathy itself. *Persistent infection in neurons of sensory ganglia is a key feature of varicella-zoster virus pathophysiology.* - This statement is true regarding the **latency** of VZV, where it remains dormant in the **sensory ganglia** after primary infection (chickenpox). - However, the question asks about features of **neuropathy associated with varicella-zoster infection** (implying reactivation leading to shingles), not the mechanism of latency itself, which is a prerequisite for reactivation.

Question 1135: Tuberculosis of spine most commonly affects which vertebral segment?

A. Upper dorsal
B. Lower dorsal (Correct Answer)
C. Lumbar
D. Cervical

Explanation: ***Lower dorsal*** - The **lower dorsal** (thoracic) spine, especially T9-T12, is the most frequently affected segment in **tuberculosis of the spine** (Pott's disease) [1]. - This region's rich vascular supply, particularly the nutrient arteries, makes it a common site for hematogenous spread of *Mycobacterium tuberculosis*. *Upper dorsal* - While other segments can be affected, the **upper dorsal spine** is less commonly involved than the lower dorsal region. - Involvement here might present with similar symptoms but is statistically less frequent. *Lumbar* - The **lumbar spine** is the second most common site for spinal tuberculosis, but it is still less frequent than the lower dorsal region [1]. - Lumbar involvement typically presents with **low back pain** and neurological deficits but is not the primary site. *Cervical* - **Cervical spine** involvement in tuberculosis is rare, accounting for a small percentage of all spinal TB cases. - It can lead to severe neurological compromise due to the **narrow spinal canal** in this region.

Question 1136: Which of the following is an ocular complication associated with Zika virus infection?

A. Liver inflammation
B. Heart inflammation
C. Eye inflammation (Correct Answer)
D. None of the options

Explanation: ***Eye inflammation*** - **Ocular manifestations** are recognized complications of **Zika virus infection**, ranging from conjunctivitis to more severe conditions like **uveitis** and **optic neuritis**. - Specifically, **chorioretinal scars** and **optic nerve abnormalities** have been observed in infants with congenital Zika syndrome. *Liver inflammation* - **Hepatitis**, or liver inflammation, is not a common or specific complication directly associated with Zika virus infection. - While some viral infections can affect the liver, **Zika** primarily targets **neural tissues** and has specific ocular and neurological complications. *Heart inflammation* - **Myocarditis**, or heart inflammation, is not a frequently reported or characteristic complication of **Zika virus infection**. - The primary systemic manifestations of **Zika** typically involve **mild fever**, **rash**, **arthralgia**, and **conjunctivitis**, with severe outcomes usually being neurological. *None of the options* - This option is incorrect because **eye inflammation** is a well-documented and significant ocular complication of **Zika virus infection**. - The virus is known to have **tropism for ocular tissues**, leading to various visual impairments.

Question 1137: A 60-year-old farmer presents with swelling on the sole of the foot accompanied by discharging yellow granules. What is the most likely diagnosis?

A. Fungal mycetoma
B. Actinomycosis (Correct Answer)
C. Candidiasis
D. Actinomycetoma

Explanation: ***Actinomycosis*** - The presentation of a **slowly progressive swelling** with **draining sinuses** that exude **"sulfur granules" (yellow granules)** is highly characteristic of actinomycosis. - While often associated with the cervicofacial region, actinomycosis can affect other sites such as the foot, especially after **trauma** or through direct inoculation from soil, consistent with a farmer's occupation. *Fungal mycetoma* - While fungal mycetoma also presents with **swelling, draining sinuses**, and **granules**, these granules are typically **black or white** from fungal elements, not yellow [1]. - The causative agents are true fungi, and the clinical course might differ subtly, but the **color of the granules** is a key differentiator [1]. *Actinomycetoma* - Actinomycetoma is caused by **filamentous bacteria** (like *Nocardia* or *Actinomadura*), which are a type of bacterial mycetoma. It presents similarly to fungal mycetoma with **granules**, but these are usually **white, red, or yellow-brown**, and less commonly the bright yellow "sulfur granules" seen in classical actinomycosis. - It’s important to distinguish actinomycetoma (bacterial mycetoma) from actinomycosis, which is caused by *Actinomyces* species and is characterized specifically by the classic sulfur granules. *Candidiasis* - **Candidiasis** (yeast infection) typically presents as **mucocutaneous lesions, thrush, or invasive systemic infections**, not localized swelling with discharging yellow granules on the sole of the foot. - It does not involve the formation of granules or sinuses in this manner.

Question 1138: What is the commonest form of plague?

A. Bubonic plague (Correct Answer)
B. Pneumonic plague
C. Septicaemic plague
D. Hemorrhagic plague

Explanation: ***Bubonic plague*** - This is the **most common** form of plague, accounting for the majority of human cases [1]. - It is characterized by the development of painful, swollen lymph nodes called **buboes**, typically in the groin, armpit, or neck. *Pneumonic plague* - This form affects the **lungs** and is less common, but it is the most **virulent** and can be transmitted directly from person to person via respiratory droplets [1]. - If left untreated, bubonic or septicaemic plague can progress to secondary pneumonic plague [1]. *Septicaemic plague* - This form occurs when the bacteria **multiply in the bloodstream**, leading to widespread infection and potentially septic shock [1]. - It is less common than bubonic plague and can occur as a primary infection or as a complication of untreated bubonic plague [1]. *Hemorrhagic plague* - While plague can cause **hemorrhage** due to disseminated intravascular coagulation, "hemorrhagic plague" is not a distinct, recognized form of plague. - Bleeding is a **symptom** that can occur in severe cases of septicaemic or pneumonic plague, indicating extensive organ damage.

Question 1139: Non-parasitic eosinophilia is caused by infection with -

A. Coccidioidomycosis (Valley Fever) (Correct Answer)
B. Ehrlichiosis
C. Candidiasis (Yeast infection)
D. Staphylococcal infection

Explanation: ***Coccidioidomycosis (Valley Fever)*** - **Coccidioidomycosis** is a systemic fungal infection that characteristically causes **non-parasitic eosinophilia**. This is a classic association frequently tested. - The host immune response to this specific fungal pathogen often involves a significant increase in **eosinophil count**. *Ehrlichiosis* - **Ehrlichiosis** is a bacterial infection transmitted by ticks, which typically causes **leukopenia** (low white blood cell count), sometimes with relative lymphocytosis. - While it affects various blood cell lines, it does not characteristically lead to **eosinophilia**; rather, it's more associated with low platelet and white cell counts. *Candidiasis (Yeast infection)* - **Candidiasis** is a common fungal infection, but it almost never causes **eosinophilia** [1]. - Systemic candidiasis is more likely to cause **neutrophilia**, rather than an increase in eosinophils [1]. *Staphylococcal infection* - **Staphylococcal infections** are bacterial and typically cause **neutrophilia** as the primary response.

Question 1140: Which of the following statements about amoebiasis is correct?

A. The abscess wall provides the highest yield for Entamoeba histolytica culture
B. Amoebic liver abscess occurs in 10% of intestinal amoebiasis cases in tropical regions (Correct Answer)
C. The portal circulation prevents systemic spread of Entamoeba histolytica
D. Amoebic liver abscesses are formed primarily due to bacterial suppuration

Explanation: ***Amoebic liver abscess occurs in 10% of intestinal amoebiasis cases in tropical regions*** - While exact percentages vary, **amoebic liver abscess** (ALA) is a common complication of intestinal amoebiasis, particularly in endemic tropical and subtropical areas. [1] - The development of ALA from intestinal infection occurs in a significant minority of cases, with figures generally cited as around **10%**, highlighting its clinical importance. *The abscess wall provides the highest yield for Entamoeba histolytica culture* - **Entamoeba histolytica** trophozoites are typically found at the **periphery** of the abscess cavity, not directly within the necrotic contents or the thick abscess wall, which is largely acellular. - Aspirated pus from an ALA often yields **negative cultures** for *E. histolytica* because the central material is necrotic and does not contain viable trophozoites. *The portal circulation prevents systemic spread of Entamoeba histolytica* - The **portal circulation** is the primary route by which *Entamoeba histolytica* trophozoites spread from the intestinal wall to the liver, leading to the formation of amoebic liver abscesses. [1] - Far from preventing systemic spread, the portal system facilitates the **hemosiderin** spread of the parasite to the liver, its most common extraintestinal site of infection. *Amoebic liver abscesses are formed primarily due to bacterial suppuration* - Amoebic liver abscesses are a result of tissue destruction caused by **Entamoeba histolytica** trophozoites, which invade the liver parenchyma and cause liquefactive necrosis. [1] - While secondary bacterial infection can occur, the primary pathology is due to the **protozoan parasite** itself, not bacterial suppuration. The classic pus is often described as "anchovy paste" due to necrotic liver tissue. [1, 5]

Practice by Chapter

Principles of Antimicrobial Therapy

Practice Questions

Fever of Unknown Origin

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HIV/AIDS and Related Infections

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Tuberculosis and Mycobacterial Diseases

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Tropical and Parasitic Infections

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Viral Infections (Hepatitis, Herpes, etc.)

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Healthcare-Associated Infections

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Fungal Infections

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Sepsis and Septic Shock

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Infection in Immunocompromised Hosts

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Emerging and Re-emerging Infections

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Antimicrobial Resistance

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Vaccination Principles

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