Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 1141: Which of the following is NOT an extrahepatic manifestation of Hepatitis C?

A. Glomerulonephritis
B. Cryoglobulinemia
C. Lichen Planus
D. Celiac Disease (Correct Answer)

Explanation: ***Celiac Disease*** - Celiac disease is an **autoimmune disorder** triggered by gluten, not associated with Hepatitis C. [1] - Extrahepatic manifestations of Hepatitis C typically include **dermatological and rheumatological conditions**, which are absent in celiac disease. *Cryoglobulinemia* - Cryoglobulinemia is a common **extrahepatic manifestation** of Hepatitis C, often leading to **vasculitis**. - It presents with **skin rashes**, arthralgia, and renal issues, significantly associated with chronic Hepatitis C infection [2]. *Lichen Planus* - Lichen Planus is another **dermatological condition** frequently linked with Hepatitis C, manifesting with **itchy lesions** on skin and mucous membranes. - The exact mechanism is unclear, but it shows a significant correlation with the virus. *Glomerulonephritis* - Glomerulonephritis is also recognized as a potential **extrahepatic complication** of Hepatitis C, often resulting from **cryoglobulinemic vasculitis**. - It can lead to symptoms of **nephritis**, such as hematuria and proteinuria, reflecting kidney involvement [2].

Question 1142: CCR5 mutation is related to which condition ?

A. Resistance to HIV infection (Correct Answer)
B. Susceptibility to HIV infection
C. Resistance to HBV infection
D. Susceptibility to HBV infection

Explanation: ***Resistance to HIV infection*** - A specific mutation, **CCR5-delta32**, leads to a non-functional **CCR5 receptor** on the surface of immune cells. - Since **HIV** primarily uses the **CCR5 receptor** to enter target cells, individuals with this mutation are highly resistant to HIV infection. *Susceptibility to HIV infection* - A functional **CCR5 receptor** is required for most **HIV** strains (R5 strains) to enter human cells. - Mutations leading to a non-functional **CCR5 receptor** decrease, rather than increase, susceptibility to HIV. *Resistance to HBV infection* - The **hepatitis B virus (HBV)** uses different cellular receptors for entry, primarily the **sodium taurocholate co-transporting polypeptide (NTCP)**. - **CCR5** mutations have no known effect on susceptibility or resistance to **HBV infection**. *Susceptibility to HBV infection* - Susceptibility to **HBV** infection is determined by the presence and functionality of its specific entry receptors, such as NTCP. - **CCR5** mutations do not impact these pathways and therefore do not influence susceptibility to **HBV**.

Question 1143: 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 1144: 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 1145: A complicated urinary tract infection (UTI) is defined as an infection that fails to resolve or recurs within how much time of standard therapy?

A. 1 week
B. 2 weeks (Correct Answer)
C. 3 weeks
D. 4 weeks

Explanation: **2 weeks** - A complicated urinary tract infection (UTI) is defined by its failure to resolve or recurrence within **two weeks** of completing standard antimicrobial therapy [1]. - This time frame is crucial for identifying UTIs that may be associated with **structural or functional abnormalities** of the urinary tract [1]. *1 week* - While recurrence within one week is certainly concerning, the standard definition for a complicated UTI due to treatment failure or recurrence extends to the two-week mark. - Assessing treatment efficacy over one week might be too short to definitively label a UTI as complicated in all cases. *3 weeks* - If a UTI recurs after three weeks, it is often considered a **reinfection** rather than a failure of the initial treatment or an indicator of a complicated UTI from the original episode [1]. - The focus for defining complicated UTI is typically on earlier recurrence or failure to achieve cure within a shorter, defined period. *4 weeks* - Recurrence after four weeks is generally considered a new infection or reinfection, rather than a failure of the initial therapy for a complicated UTI [1]. - The timeframe for classifying a UTI as complicated due to inadequate initial treatment response is specifically within weeks, not months.

Question 1146: Which hepatitis infection is most commonly associated with immune thrombocytopenic purpura?

A. Hepatitis A infection
B. Hepatitis B infection
C. Hepatitis C infection (Correct Answer)
D. Hepatitis D infection

Explanation: ***Hepatitis C infection*** - **Hepatitis C** is well-established for causing various **extrahepatic manifestations**, including mixed cryoglobulinemia, membranoproliferative glomerulonephritis, and **immune thrombocytopenic purpura (ITP)**. - The mechanism involves chronic viral stimulation leading to the production of **autoantibodies** against platelets and megakaryocytes, or direct viral effects on bone marrow. *Hepatitis A infection* - **Hepatitis A** is an **acute, self-limiting viral infection** [1] that typically does not lead to chronic liver disease or significant extrahepatic manifestations like ITP. - There are rare reports of transient thrombocytopenia in acute hepatitis A, but it is not commonly associated with chronic ITP. *Hepatitis B infection* - While **Hepatitis B** can cause extrahepatic manifestations such as polyarteritis nodosa and glomerulonephritis, its association with **immune thrombocytopenic purpura (ITP)** is less frequent and not as strong as with Hepatitis C. - HBV-associated thrombocytopenia is more often related to **hypersplenism** in cirrhotics or direct viral bone marrow suppression, rather than immune-mediated destruction. *Hepatitis D infection* - **Hepatitis D (HDV)** is a **defective virus** that requires co-infection with Hepatitis B virus (HBV) to replicate. - Its extrahepatic manifestations are primarily linked to the underlying **HBV infection**, and there is no strong, independent association with immune thrombocytopenic purpura.

Question 1147: Which of the following characteristics does NOT apply to the rash of chickenpox when differentiating it from smallpox?

A. Not centripetal
B. Deep-seated (Correct Answer)
C. Monomorphic
D. Superficial

Explanation: ***Deep-seated*** - The rash of chickenpox is typically **superficial**, affecting the epidermis and upper dermis, leading to vesicles that are easily ruptured [1]. - In contrast, a **deep-seated** rash is characteristic of smallpox, where lesions extend into the deeper dermis, giving them a firm, "shotty" feel upon palpation. *Not centripetal* - This statement is generally true for chickenpox; its rash distribution tends to be **centrifugal**, meaning it is more concentrated on the trunk and extremities, sparing the face and distal limbs [1]. - Smallpox, however, is characterized by a **centripetal distribution**, with lesions most concentrated on the face and extremities. *Monomorphic* - This characteristic does NOT apply to chickenpox. Chickenpox exhibits a **pleomorphic rash**, meaning lesions at various stages of development (macules, papules, vesicles, scabs) are present simultaneously [1]. - A **monomorphic rash**, where all lesions are at the same stage of development, is a hallmark of smallpox. *Superficial* - This characteristic **applies** to chickenpox [1]. The lesions are typically superficial, affecting the epidermal layers and leading to a fragile, easily ruptured vesicle. - Smallpox lesions, in contrast, are **deep-seated**, firm, and umbilicated.

Question 1148: 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 1149: 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 1150: 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.

Practice by Chapter

Principles of Antimicrobial Therapy

Practice Questions

Fever of Unknown Origin

Practice Questions

HIV/AIDS and Related Infections

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Tuberculosis and Mycobacterial Diseases

Practice Questions

Tropical and Parasitic Infections

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Viral Infections (Hepatitis, Herpes, etc.)

Practice Questions

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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