Cardiovascular Infections — MCQs
Infantile myocarditis and pericarditis is due to
In rheumatic heart disease, infective endocarditis is detected by echocardiogram and the largest vegetations seen are due to -
Infective endocarditis is least common in whom?
Which of the following is a minor criterion for the diagnosis of acute rheumatic fever?
Which of the following is not a complication of infective endocarditis?
Chagas disease is transmitted by the following:
A Giemsa stain of a thin peripheral blood smear is prepared. Which of the following cannot be diagnosed?
A 40-year-old gardener presents with several subcutaneous nodules on his right hand, where he had cut himself on rose thorns, and physical examination reveals several erythematous fluctuant lesions. Which organism is most likely responsible for his condition?
Which of the following diseases is caused by the virus shown below?
Which organism does not require a vector for transmission?
Cardiovascular Infections Indian Medical PG Practice Questions and MCQs
Question 1: Infantile myocarditis and pericarditis is due to
- A. Pox virus
- B. Coxsackie B (Correct Answer)
- C. Mumps
- D. Coxsackie A
Explanation: **Coxsackie B** - **Coxsackie B virus** is a well-established cause of **viral myocarditis and pericarditis**, particularly in infants and young children. - The virus can directly infect myocardial cells, leading to inflammation and damage. - Coxsackie B is the **most common viral cause** of infantile myocarditis. *Pox virus* - **Poxviruses** primarily cause **skin lesions** (e.g., smallpox, molluscum contagiosum) and are not a common cause of myocarditis or pericarditis. - While systemic infections can occur, cardiac involvement is **rare and not a typical presentation**. *Mumps* - **Mumps virus** is known for causing **parotitis** (inflammation of the salivary glands), and can also cause complications such as orchitis, meningitis, and pancreatitis. - While **mumps myocarditis** can occur, it is a **less common** presentation compared to Coxsackie B virus. *Coxsackie A* - **Coxsackie A viruses** are more commonly associated with conditions like **herpangina** (oral lesions) and **hand-foot-and-mouth disease**. - While they can occasionally cause myocarditis, **Coxsackie B viruses** are far more frequently implicated in cases of viral myocarditis and pericarditis.
Question 2: In rheumatic heart disease, infective endocarditis is detected by echocardiogram and the largest vegetations seen are due to -
- A. Candida albicans
- B. Staphylococcus aureus (Correct Answer)
- C. Salmonella typhi
- D. Streptococcus viridans
Explanation: Staphylococcus aureus - Staphylococcus aureus is well-known for causing aggressive infective endocarditis with large, destructive vegetations due to its virulence factors [1]. - These large vegetations are easily detectable by echocardiogram and are associated with a higher risk of embolic events and valve destruction [1]. Candida albicans - While Candida albicans can cause endocarditis, often in immunocompromised individuals or IV drug users, its vegetations are typically larger and more friable than most bacterial causes but S. aureus still produces larger bacterial vegetations due to its rapid colonization and biofilm formation. - Fungal endocarditis generally has a poorer prognosis and requires prolonged antifungal therapy. Salmonella typhi - Salmonella typhi is a less common cause of infective endocarditis; when it does occur, it is often associated with immunocompromised states or pre-existing cardiac lesions. - The vegetations caused by Salmonella are generally not as large or rapidly destructive as those seen with S. aureus. Streptococcus viridans - Streptococcus viridans is a frequent cause of subacute infective endocarditis, particularly on previously damaged valves [1]. - The vegetations are typically small to medium-sized and less destructive than those caused by S. aureus, leading to more indolent disease [1].
Question 3: Infective endocarditis is least common in whom?
- A. ASD. (Correct Answer)
- B. Mitral stenosis.
- C. VSD.
- D. Aortic stenosis.
Explanation: ***ASD*** - Infective endocarditis is **least common** in atrial septal defects (ASDs) because the low-pressure, laminar flow across the defect does not typically create the turbulent jet lesions that predispose to vegetations. - While vegetations can form on damaged endothelium, the **absence of high-pressure gradients** makes it less likely [1]. *Mitral stenosis* - **Mitral stenosis** can increase the risk of infective endocarditis, particularly when associated with **severe valvular calcification** or **rheumatic heart disease**. - The turbulent flow and predisposition to atrial fibrillation can contribute to endothelial damage and vegetation formation [1]. *VSD* - **Ventricular septal defects (VSDs)** are considered a **high-risk congenital heart lesion** for infective endocarditis due to the turbulent blood flow from the left ventricle to the right ventricle [1]. - The high-velocity jet can cause **endothelial injury**, making the area susceptible to bacterial adherence and vegetation formation. *Aortic stenosis* - **Aortic stenosis** is a significant risk factor for infective endocarditis, especially in **bicuspid aortic valves** or those with **degenerative calcification** [1]. - The turbulent flow across the stenotic valve creates a predisposition to valve damage and subsequent bacterial adherence.
Question 4: Which of the following is a minor criterion for the diagnosis of acute rheumatic fever?
- A. Subcutaneous nodules
- B. Carditis
- C. Chorea
- D. Fever (Correct Answer)
Explanation: ***Fever*** - **Fever** is a minor diagnostic criterion for **acute rheumatic fever** (ARF), indicating systemic inflammation [1]. - While non-specific, its presence alongside other criteria supports the diagnosis, particularly in the context of recent streptococcal infection. *Subcutaneous nodules* - **Subcutaneous nodules** are a **major criterion** for ARF, typically firm, painless lumps found over bony prominences. - Their presence indicates more severe, chronic inflammation in ARF. *Carditis* - **Carditis** is a **major criterion** for ARF, referring to inflammation of the heart, which can affect the pericardium, myocardium, or endocardium [1]. - It is the most serious manifestation of ARF, as it can lead to permanent **rheumatic heart disease** [2]. *Chorea* - **Chorea** (specifically **Sydenham chorea**) is a **major criterion** for ARF, characterized by involuntary, jerky movements, often presenting late in the disease course [1]. - It results from inflammation affecting the basal ganglia.
Question 5: Which of the following is not a complication of infective endocarditis?
- A. Focal and diffuse glomerulonephritis
- B. Myocardial ring abscess
- C. Suppurative pericarditis
- D. Myocardial infarction (Correct Answer)
Explanation: ***Myocardial infarction*** - While infective endocarditis can lead to various cardiac complications, **myocardial infarction** due to direct coronary artery occlusion by emboli from vegetations is **rare** and not considered a typical complication. [1] - Myocardial infarction is more commonly associated with **atherosclerotic coronary artery disease**. *Myocardial ring abscess* - This is a common and severe local complication of infective endocarditis, often occurring in cases involving **virulent organisms** or **prosthetic valves**. [1] - An abscess can extend into the **myocardium**, conduction system, or pericardium, leading to heart block or valvular dehiscence. *Focal and diffuse glomerulonephritis* - These are **immune-mediated renal complications** of infective endocarditis, caused by the deposition of immune complexes in the glomeruli. [1] - Often presents with **hematuria**, proteinuria, and renal impairment, reflecting the systemic inflammatory response. [1] *Suppurative pericarditis* - This can occur if the infection from the endocarditic vegetation extends into the **pericardial space**, either directly or via a myocardial abscess. - It involves **purulent inflammation** of the pericardium, leading to chest pain, fever, and potentially tamponade.
Question 6: Chagas disease is transmitted by the following:
- A. Birds
- B. Kissing bugs (Correct Answer)
- C. Tsetse flies
- D. Dogs
Explanation: ***Kissing bugs*** - Chagas disease is primarily transmitted by the feces of infected **triatomine bugs**, commonly known as **kissing bugs**, which typically feed at night. - These bugs transmit the parasite *Trypanosoma cruzi* when they defecate near the bite wound or mucous membranes. *Birds* - Birds are not known vectors for the transmission of **Chagas disease**. - While some birds can carry other diseases, they do not carry the **triatomine bug** or the *Trypanosoma cruzi* parasite. *Tsetse flies* - **Tsetse flies** are the primary vectors for **African trypanosomiasis** (sleeping sickness), caused by *Trypanosoma brucei*. - They are not involved in the transmission of **Chagas disease** (*Trypanosoma cruzi*). *Dogs* - While dogs can be reservoirs for the *Trypanosoma cruzi* parasite and can become infected with **Chagas disease**, they are not directly responsible for transmitting the disease to humans. - Transmission to dogs and humans occurs through the bite of an infected **kissing bug**.
Question 7: A Giemsa stain of a thin peripheral blood smear is prepared. Which of the following cannot be diagnosed?
- A. Coxiella burnettii (Correct Answer)
- B. Bartonella henselae
- C. Ehrlichia chaffeensis
- D. Toxoplasma gondii
Explanation: ***Coxiella burnettii*** - *Coxiella burnettii* causes **Q fever** and is an **obligate intracellular bacterium** that resides primarily in **tissue macrophages** (lungs, liver, bone marrow), not in circulating blood cells. - It is **not found in peripheral blood smears** because it does not infect circulating leukocytes in significant numbers that would allow microscopic visualization. - Diagnosis requires **serology** (most common), **PCR**, or specialized culture in BSL-3 facilities—direct microscopic visualization in blood smears is not possible. *Bartonella henselae* - Causes **Cat scratch disease** and can invade **red blood cells**, making it potentially visible on Giemsa-stained blood smears, particularly in immunocompromised patients with bacillary angiomatosis or bacteremia. - While difficult and not the primary diagnostic method, it *can* be visualized in peripheral blood, unlike *Coxiella*. *Ehrlichia chaffeensis* - Causes **human monocytotropic ehrlichiosis (HME)** and forms characteristic **morulae** (berry-like clusters) within the cytoplasm of **monocytes**. - These morulae are readily visible on **Giemsa-stained peripheral blood smears** and are a key diagnostic finding, making this condition easily diagnosed by this method. *Toxoplasma gondii* - An **intracellular parasite** whose **tachyzoites** can occasionally be found in **peripheral blood leukocytes** during acute infection, especially in immunocompromised patients. - While rare and not the primary diagnostic method (serology/PCR preferred), tachyzoites *can* be observed in blood smears during active parasitemia.
Question 8: A 40-year-old gardener presents with several subcutaneous nodules on his right hand, where he had cut himself on rose thorns, and physical examination reveals several erythematous fluctuant lesions. Which organism is most likely responsible for his condition?
- A. Aspergillus
- B. Malassezia
- C. Sporothrix (Correct Answer)
- D. Histoplasma
Explanation: ***Sporothrix*** - The gardener's history of a cut from rose thorns and the development of **subcutaneous nodules** are classic presentations of **sporotrichosis** (rose gardener's disease), caused by *Sporothrix schenckii*. - *Sporothrix schenckii* is a **dimorphic fungus** found in soil and on plant matter, causing localized cutaneous or subcutaneous lesions that typically follow **lymphatic spread** (lymphocutaneous pattern). *Aspergillus* - *Aspergillus* species typically cause **invasive pulmonary infections** (aspergillosis) in immunocompromised individuals or allergic bronchopulmonary aspergillosis. - While it can cause cutaneous infections, these are rare and usually occur in severely immunocompromised patients, without the classic "rose thorn" association. *Malassezia* - *Malassezia* species are yeasts that are normal skin flora and are primarily associated with **pityriasis versicolor**, **seborrheic dermatitis**, and **folliculitis**. - They do not typically cause deep subcutaneous nodules or are associated with puncture wounds from plants. *Histoplasma* - *Histoplasma capsulatum* is a **dimorphic fungus** that primarily causes **pulmonary infections** through inhalation of spores from soil contaminated with bird or bat droppings. - While it can rarely cause cutaneous lesions (especially in disseminated disease in immunocompromised patients), it is not associated with traumatic inoculation from plant material or the lymphocutaneous pattern seen here.
Question 9: Which of the following diseases is caused by the virus shown below?
- A. Neurodegenerative disorder
- B. Swimming pool conjunctivitis (Correct Answer)
- C. Solid organ graft infection
- D. Solid organ graft rejection
Explanation: ***Swimming pool conjunctivitis*** - The image displays an **adenovirus**, characterized by its **icosahedral shape** and distinct **fiber proteins** projecting from the vertices. - Adenoviruses are a common cause of **pharyngoconjunctival fever**, often referred to as "swimming pool conjunctivitis" due to its spread in **inadequately chlorinated swimming pools**. - This is the **most characteristic disease** associated with adenovirus infection, particularly serotypes **3, 4, and 7**. *Neurodegenerative disorder* - Adenoviruses are **not associated** with neurodegenerative disorders. - Neurodegenerative conditions are typically linked to **prions, misfolded proteins**, or other viral agents like **JC virus** (progressive multifocal leukoencephalopathy). - Adenoviruses cause **acute infections**, not chronic neurodegeneration. *Solid organ graft infection* - While adenoviruses can cause severe infections in **immunocompromised patients**, including transplant recipients, this is not their most characteristic presentation. - In transplant patients, adenovirus may cause **colitis, hepatitis, or nephritis**, but these are **opportunistic infections** rather than the typical disease association. - The characteristic disease remains **conjunctivitis and respiratory infections** in immunocompetent hosts. *Solid organ graft rejection* - **Graft rejection** is an **immunological process** where the recipient's immune system attacks the transplanted organ, not a viral infection. - Adenovirus does not directly cause the mechanism of graft rejection. - While viral infections may complicate graft outcomes, rejection itself is **immune-mediated**, not infectious.
Question 10: Which organism does not require a vector for transmission?
- A. Rickettsia rickettsii
- B. Borrelia recurrentis
- C. Rickettsia prowazekii
- D. Coxiella burnetii (Correct Answer)
Explanation: ***Coxiella burnetii*** - This organism causes **Q fever** and does not require an arthropod vector; it is primarily transmitted via **aerosols** from infected animals. - Humans usually acquire the infection by inhaling **contaminated aerosols** from infected livestock (cattle, sheep, goats). *Rickettsia prowazekii* - This bacterium is the causative agent of **epidemic typhus** and is transmitted by the **human body louse** (*Pediculus humanus corporis*). - The louse acts as a **biological vector**, acquiring the organism from an infected human and transmitting it through its feces, which are then scratched into the skin. *Rickettsia rickettsii* - This organism causes **Rocky Mountain Spotted Fever (RMSF)** and is transmitted by **ticks**, primarily the American dog tick (*Dermacentor variabilis*) and the Rocky Mountain wood tick (*Dermacentor andersoni*). - Ticks serve as both **vectors** and **reservoirs** for *Rickettsia rickettsii*. *Borrelia recurrentis* - This spirochete causes **louse-borne relapsing fever** and is transmitted by the **human body louse** (*Pediculus humanus corporis*). - Transmission occurs when the louse is crushed and its hemolymph, containing the bacteria, comes into contact with broken skin or mucous membranes.
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