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: 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 1137: 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 1138: 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 1139: 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 1140: Major criteria for infective endocarditis include which of the following

A. History of injection drug use
B. Presence of Osler's nodes
C. Isolation of a typical organism from two separate blood cultures (Correct Answer)
D. Persistent fever for more than 4 days

Explanation: ***Isolation of a typical organism from two separate blood cultures*** - This is a definitive **major criterion** for infective endocarditis, indicating active bacterial infection in the bloodstream [1]. - The isolation of a **typical microorganism** (e.g., *S. aureus*, viridans streptococci) from multiple blood samples helps confirm the diagnosis [1]. *History of injection drug use* - While **injection drug use** is a significant **risk factor** for infective endocarditis, it is not a diagnostic major criterion itself [1]. - It increases the likelihood of infection but does not confirm the presence of endocarditis. *Presence of Osler's nodes* - **Osler's nodes** are painful, tender, red or purple lesions found on the hands and feet, which are considered **minor criteria** (immunological phenomena) for infective endocarditis [1]. - They are a clinical sign, but not as diagnostically definitive as microbiological evidence. *Persistent fever for more than 4 days* - **Fever** (temperature >38°C) is a common symptom and a **minor criterion** for infective endocarditis [1]. - However, the duration of fever alone is not a major criterion and can be indicative of many other conditions.

Practice by Chapter

Principles of Antimicrobial Therapy

Practice Questions

Fever of Unknown Origin

Practice Questions

HIV/AIDS and Related Infections

Practice Questions

Tuberculosis and Mycobacterial Diseases

Practice Questions

Tropical and Parasitic Infections

Practice Questions

Viral Infections (Hepatitis, Herpes, etc.)

Practice Questions

Healthcare-Associated Infections

Practice Questions

Fungal Infections

Practice Questions

Sepsis and Septic Shock

Practice Questions

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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