Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 1141: Pulmonary eosinophilia is found in infection with ?

A. Babesia
B. Malaria
C. Strongyloides (Correct Answer)
D. Trypanosoma

Explanation: ***Strongyloides*** - **Strongyloides stercoralis** can cause **pulmonary eosinophilia** (Löffler's syndrome) as larvae migrate through the lungs [1]. - This migration is part of the parasite's life cycle, leading to an inflammatory response with eosinophil infiltration [1]. *Babesia* - **Babesia** species primarily infect **red blood cells** and cause **hemolytic anemia**, resembling malaria. - They are transmitted by ticks and do not typically cause pulmonary eosinophilia. *Malaria* - **Malaria**, caused by Plasmodium parasites, is known for infecting **red blood cells** and causing cyclical fevers, chills, and anemia. - It does not typically present with pulmonary eosinophilia as a characteristic feature. *Trypanosoma* - **Trypanosoma** species cause **sleeping sickness** (African trypanosomiasis) and **Chagas disease** (American trypanosomiasis). - These infections affect the bloodstream, lymphatic system, and various organs, but pulmonary eosinophilia is not a hallmark.

Question 1142: What is the most common cause of death in a patient with chronic bronchiectasis?

A. Hemoptysis
B. Carcinoma
C. Right-sided heart failure
D. Infection (Correct Answer)

Explanation: ***Infection*** - Chronic bronchiectasis creates a favorable environment for **bacterial colonization** and recurrent infections due to impaired mucociliary clearance and dilated, damaged airways. [1] - These infections, often by **Pseudomonas aeruginosa** or **Haemophilus influenzae**, can lead to acute exacerbations, progressive lung damage, and ultimately **respiratory failure** or overwhelming sepsis, which are common causes of death. [1], [2] *Right-sided heart failure* - **Cor pulmonale**, or right-sided heart failure, can develop as a complication of severe bronchiectasis due to **pulmonary hypertension** from chronic hypoxemia and vascular remodeling. - While it contributes to morbidity and mortality, it is not the most common direct cause of death; the underlying lung disease and subsequent infections are usually the primary drivers. *Hemoptysis* - **Severe hemoptysis** can occur in bronchiectasis due to erosion of inflamed bronchial arteries, which can be life-threatening if massive. [2], [3] - Although it is a serious complication and can be fatal, it is not the most frequent cause of death compared to the cumulative effect of chronic infections and progressive respiratory decline. *Carcinoma* - While patients with chronic lung conditions, including bronchiectasis, may have an **increased risk of lung cancer**, it is not the most common cause of death directly attributable to bronchiectasis itself. [3] - The direct and immediate threats to life in bronchiectasis are typically related to **exacerbations, infections, and respiratory failure**.

Question 1143: 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 1144: 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]

Question 1145: 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 1146: Which tool objectively assesses the risk of adverse outcomes in a patient with pneumonia?

A. Glasgow scale
B. APACHE Score
C. Pneumonia severity index [PSI]
D. CURB - 65 criteria (Correct Answer)

Explanation: ***CURB - 65 criteria*** - The **CURB-65 criteria** is a validated tool for assessing the **severity of pneumonia** and predicting adverse outcomes such as mortality, need for intensive care, and length of hospital stay [1]. - It assesses **Confusion, Urea >7 mmol/L, Respiratory rate ≥30 breaths/min, Blood pressure <90 mmHg systolic or ≤60 mmHg diastolic**, and **age ≥65 years**, assigning points that correlate with increasing risk [1]. *Pneumonia severity index [PSI]* - The **Pneumonia Severity Index (PSI)** is another widely used tool, but it is a **more complex** - It involves 20 variables, making it more cumbersome for rapid clinical use compared to CURB-65. *APACHE Score* - The **APACHE (Acute Physiology and Chronic Health Evaluation) Score** is a general measure of disease severity used in **critically ill patients**, not specific to pneumonia. - It predicts **mortality risk** in intensive care unit (ICU) patients across various conditions. *Glasgow scale* - The **Glasgow Coma Scale (GCS)** is used to **assess the level of consciousness** in patients. - It is not a tool for specifically assessing the risk of adverse outcomes in pneumonia, but rather a component that may contribute to a pneumonia severity score.

Question 1147: Which of the following is NOT a characteristic of Dengue shock syndrome?

A. Pleural effusion
B. Thrombocytopenia
C. Decreased haemoglobin (Correct Answer)
D. Hepatomegaly

Explanation: ***Decreased haemoglobin*** - **Decreased hemoglobin** is *not* a characteristic feature of Dengue shock syndrome; rather, **hemoconcentration**, indicated by an *increased* hematocrit, is a hallmark due to plasma leakage. - While bleeding can occur in dengue, leading to decreased hemoglobin, **hemoconcentration** is a more direct and consistent sign of severe plasma leakage in Dengue Shock Syndrome [1]. *Hepatomegaly* - **Hepatomegaly** (enlarged liver) is a common finding in severe dengue, including Dengue Shock Syndrome, due to hepatic inflammation and dysfunction [1]. - This symptom reflects the systemic nature of the infection and can contribute to abdominal pain and tenderness. *Pleural effusion* - **Pleural effusion** is a key indicator of **plasma leakage**, a defining characteristic of severe dengue and Dengue Shock Syndrome [1]. - The effusion results from fluid transudation into the pleural space, often accompanied by ascites. *Thrombocytopenia* - **Thrombocytopenia** (low platelet count) is a consistent and serious finding in dengue, particularly in severe forms like Dengue Shock Syndrome [1]. - A significant drop in platelet count often precedes or accompanies the onset of shock and increases the risk of bleeding.

Question 1148: Which of the following organisms is not typically associated with causing chronic adrenal insufficiency?

A. Histoplasma capsulatum
B. Coccidioides immitis
C. Mycobacterium bovis (Correct Answer)
D. Mycobacterium tuberculosis

Explanation: ***Mycobacterium bovis*** - While *Mycobacterium bovis* can cause tuberculosis-like disease, it is **less commonly associated with chronic adrenal insufficiency** compared to *M. tuberculosis* itself, which has a predilection for adrenal tissue. - Infection with *M. bovis* primarily affects cattle and can be transmitted to humans, but its tropism for the adrenal glands leading to insufficiency is not a primary recognized feature. *Mycobacterium tuberculosis* - **Tuberculosis** is a well-known cause of chronic adrenal insufficiency, also known as **Addison's disease**, particularly in endemic regions. [1] - The bacteria can directly infect and destroy the adrenal cortex, leading to impaired hormonal production. *Histoplasma capsulatum* - **Disseminated histoplasmosis**, especially in immunocompromised individuals, can directly involve the adrenal glands. - This fungal infection can lead to **adrenal destruction and chronic adrenal insufficiency** by granuloma formation and necrosis. *Coccidioides immitis* - **Disseminated coccidioidomycosis** is another fungal infection that can cause adrenal gland involvement. - Similar to histoplasmosis, it can lead to **granulomatous inflammation and necrosis** within the adrenal cortex, resulting in chronic adrenal insufficiency.

Question 1149: Which of the following is a known risk factor for cholangiocarcinoma?

A. Giardia lamblia (intestinal protozoa) infection
B. Ascaris lumbricoides (roundworm) infection
C. Clonorchis sinensis infestation (Correct Answer)
D. Paragonimus westermani infestation

Explanation: ***Clonorchis sinensis infestation*** - **Clonorchis sinensis**, also known as the Chinese liver fluke, is a well-established and significant risk factor for the development of **cholangiocarcinoma**. - Chronic inflammation and irritation of the bile ducts caused by the parasite are believed to promote malignant transformation. *Giardia lamblia (intestinal protozoa) infection* - **Giardia lamblia** is a common intestinal parasite causing giardiasis, characterized by diarrhea and malabsorption. - While it affects the gastrointestinal tract, there is **no known association** between *Giardia* infection and an increased risk of cholangiocarcinoma. *Paragonimus westermani infestation* - **Paragonimus westermani** is a lung fluke that primarily causes paragonimiasis, affecting the lungs and leading to cough and hemoptysis. - This parasite is not associated with direct bile duct inflammation or an increased risk of **cholangiocarcinoma**. *Ascaris lumbricoides (roundworm) infection* - **Ascaris lumbricoides** is a large intestinal roundworm that can cause intestinal obstruction or nutrient deficiencies. - Although it can occasionally migrate into the biliary tree, it is **not considered a risk factor** for cholangiocarcinoma [1].

Question 1150: 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.

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Principles of Antimicrobial Therapy

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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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