Endocarditis — MCQs
Which organism causes prosthetic valve endocarditis within 60 days of surgery?
What are the essential major blood culture criteria for diagnosing infective endocarditis?
Infective endocarditis is not seen in –
A 28 year old man with 3 weeks of fever presented with tricuspid valve vegetation. What is the MOST common cause of Endocarditis in I.V. drug abusers?
A 6-year-old with congenital heart disease presents with fever, new-onset murmur, and petechiae. Blood cultures are pending, but initial Gram stain shows Gram-positive cocci. What is the most appropriate initial intervention?
Which of the following is not a complication of infective endocarditis?
Vegetations in Libman-Sacks endocarditis are:
Flat vegetations in valve pockets due to deposition on previously normal valve surfaces are characteristic of:
Which among the following is true about non-bacterial thrombotic endocarditis (NBTE)?
Vegetations on under surface of cusps are found in:
Endocarditis Indian Medical PG Practice Questions and MCQs
Question 1: Which organism causes prosthetic valve endocarditis within 60 days of surgery?
- A. Staphylococcus aureus
- B. Staphylococcus epidermidis (Correct Answer)
- C. Fungus
- D. Streptococcus viridans
Explanation: ***Staphylococcus epidermidis*** - This organism is the **most common cause of early prosthetic valve endocarditis (within 60 days of surgery)**, accounting for 30-40% of cases. - As a coagulase-negative Staphylococcus, *S. epidermidis* commonly colonizes the skin and can be introduced during the surgical procedure. - It produces **biofilms**, which allow it to adhere to prosthetic surfaces and resist antibiotic treatment. *Staphylococcus aureus* - *Staphylococcus aureus* is the **second most common cause of early prosthetic valve endocarditis** (20-25% of cases) and can cause both early and late infections. - It typically presents with a more **fulminant, aggressive course** compared to *S. epidermidis*. - While both staphylococcal species cause early PVE, *S. epidermidis* remains more frequent. *Fungus* - **Fungal endocarditis** on prosthetic valves (typically *Candida* species) accounts for 5-10% of early PVE cases. - More commonly seen in immunocompromised patients, those with prolonged antibiotic use, or after complicated cardiac surgery. - Its incidence is significantly lower than staphylococcal causes in the early post-operative period. *Streptococcus viridans* - *Streptococcus viridans* is the **most common cause of native valve endocarditis**, particularly in patients with pre-existing valvular heart disease. - It typically causes a **subacute presentation** and is more associated with **late prosthetic valve endocarditis** (>60 days post-surgery), not early PVE. - Rarely implicated in early prosthetic valve infections.
Question 2: What are the essential major blood culture criteria for diagnosing infective endocarditis?
- A. Single positive culture of Coxiella burnetii (Correct Answer)
- B. Single positive culture of Corynebacterium species
- C. Both HACEK and Coxiella cultures
- D. Single positive culture of HACEK group
Explanation: ***Single positive culture of Coxiella burnetii*** - A single positive blood culture for **Coxiella burnetii** or **anti-phase I IgG antibody titer > 1:800** is considered a major criterion for infective endocarditis due to its highly pathogenic nature in this context [1], [2]. - This organism is a known cause of **culture-negative endocarditis**, and specific serology or molecular tests are often required for diagnosis [1]. *Single positive culture of Corynebacterium species* - **Corynebacterium species** are often considered **contaminants** in blood cultures, especially *Corynebacterium jeikeium*, and typically require multiple positive cultures, often from different sites, to be considered significant pathogens for infective endocarditis [2]. - A single positive culture of these organisms alone is generally insufficient to meet major diagnostic criteria for endocarditis [2]. *Both HACEK and Coxiella cultures* - While both **HACEK organisms** and **Coxiella burnetii** can cause endocarditis, the combination of both is not a specific major criterion in itself. - The diagnostic criteria address each organism individually [2]. *Single positive culture of HACEK group* - **HACEK organisms** (**H**aemophilus, **A**ggregatibacter, **C**ardiobacterium, **E**ikenella, **K**ingella) are well-known causes of endocarditis, but usually require **two separate positive blood cultures** for infective endocarditis major criteria [2]. - A single positive culture of a HACEK organism is typically classified as a minor criterion unless other supporting evidence is present.
Question 3: Infective endocarditis is not seen in –
- A. TOF
- B. VSD
- C. ASD (Correct Answer)
- D. MR
Explanation: Atrial septal defect (ASD) is generally considered a low-risk lesion for infective endocarditis because the pressure gradient across the defect is low, leading to less turbulent flow and less endothelial damage. While IE very rarely occurs, it is not common cause for IE. Generally the risk of infective endocarditis in an uncomplicated ASD is comparable to the general population. Tetralogy of Fallot (TOF) is a cyanotic congenital heart disease characterized by four defects (pulmonary stenosis, VSD, overriding aorta, right ventricular hypertrophy) that create turbulent flow, significantly increasing the risk of infective endocarditis. The abnormal anatomy and high flow jets in TOF predispose the heart valves and endocardium to damage, making them fertile ground for bacterial adherence and infection. Ventricular septal defect (VSD) involves an abnormal opening between the ventricles, causing a high-pressure, high-velocity jet of blood flow [1]. This turbulent flow leads to endothelial damage, particularly on the right ventricular side of the defect or the tricuspid valve, creating a nidus for bacterial colonization and infective endocarditis [1]. Mitral regurgitation (MR), especially due to degenerative valve disease or rheumatic heart disease, creates turbulent backward flow into the left atrium during systole. This chronic turbulent flow can cause endothelial injury on the mitral valve leaflets or the atrial wall, increasing the susceptibility to bacterial adherence and subsequent infective endocarditis.
Question 4: A 28 year old man with 3 weeks of fever presented with tricuspid valve vegetation. What is the MOST common cause of Endocarditis in I.V. drug abusers?
- A. Pseudomonas
- B. Candida albicans
- C. Streptococcus viridans
- D. Staph.aureus (Correct Answer)
Explanation: ***Staph.aureus*** - **_Staphylococcus aureus_** is the most common cause of **infective endocarditis** in intravenous drug abusers due to its prevalence on the skin and ability to adhere to damaged endothelial surfaces [1]. - The organism frequently accesses the bloodstream through contaminated needles, leading to tricuspid valve involvement as it is the first valve encountered by venous blood. *Pseudomonas* - While **_Pseudomonas aeruginosa_** can cause endocarditis, particularly in _IV drug users_ or immunocompromised individuals, it is significantly less common than **_Staphylococcus aureus_**. - Its infections are often associated with more severe, rapidly progressive disease and may be more challenging to treat. *Candida albicans* - **_Candida albicans_** can cause endocarditis, especially in **immunocompromised patients** or those with **indwelling catheters** or prosthetic valves, but it is not the most common cause in intravenous drug abusers [2]. - Fungal endocarditis is generally rarer than bacterial endocarditis and has a higher mortality rate. *Streptococcus viridans* - **_Streptococcus viridans_** group is a common cause of subacute bacterial endocarditis, especially in patients with **pre-existing valvular heart disease** [1]. - However, in the context of intravenous drug abuse, **_Staphylococcus aureus_** is significantly more prevalent than **_Streptococcus viridans_** [1].
Question 5: A 6-year-old with congenital heart disease presents with fever, new-onset murmur, and petechiae. Blood cultures are pending, but initial Gram stain shows Gram-positive cocci. What is the most appropriate initial intervention?
- A. Schedule for urgent valve replacement
- B. Administer high-dose steroids
- C. Start broad-spectrum antibiotics (Correct Answer)
- D. Wait for susceptibility testing
Explanation: ***Start broad-spectrum antibiotics*** - The presentation of **fever**, **new-onset murmur**, **petechiae**, and **Gram-positive cocci** in a patient with **congenital heart disease** is highly suggestive of **infective endocarditis**. - Prompt initiation of **broad-spectrum antibiotics** is crucial to prevent further damage to the heart valves and systemic complications while awaiting definitive culture results. *Schedule for urgent valve replacement* - **Valve replacement** is a definitive treatment for severe valvular damage but is typically considered after initial medical management has failed or in cases of severe complications like heart failure or recurrent emboli. - It is not the initial intervention for suspected infective endocarditis. *Administer high-dose steroids* - **Steroids** are anti-inflammatory but are not indicated in the treatment of active bacterial infections like endocarditis. - Administering steroids could potentially worsen the infection by suppressing the immune response. *Wait for susceptibility testing* - **Waiting for susceptibility testing** to initiate treatment would delay critical care, allowing the infection to progress and increasing morbidity and mortality. - Initial treatment should be empiric, and antibiotics can be narrowed once susceptibility results are available.
Question 6: 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 7: Vegetations in Libman-Sacks endocarditis are:
- A. Large and fragile
- B. Small warty along the line of closure of valve
- C. Small or medium sized on either or both sides of valve (Correct Answer)
- D. Small bland vegetations
Explanation: ***Small or medium sized on either or both sides of valve*** - **Libman-Sacks endocarditis** typically presents with vegetations that are **small to medium in size**, found on either aspect of the valve leaflets [1][2][3]. - These vegetations are **sterile**, non-infectious, and often associated with systemic lupus erythematosus (SLE) [2][3]. *Large and fragile* - Vegetations in Libman-Sacks endocarditis are not typically **large**; they are small or medium [1]. - The term **fragile** is misleading, as the vegetations are not characterized by fragility but by being sturdy yet non-infectious. *Small warty along the line of closure of valve* - While the vegetations are small, they are **not warty** and do not primarily form along the line of closure, which is common in infective endocarditis [1]. - Libman-Sacks vegetations can be found on either side of the valve, unlike warty vegetations [1]. *Small bland vegetations* - Vegetations in Libman-Sacks endocarditis are bland but not solely described as **small and bland**; their presence on either or both sides of the valve is critical [1]. - This option fails to capture the significance of their size and localization in the endocardial lesions associated with SLE. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 568. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 232-233. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 570.
Question 8: Flat vegetations in valve pockets due to deposition on previously normal valve surfaces are characteristic of:
- A. Non-bacterial thrombotic endocarditis (NBTE) (Correct Answer)
- B. Infective endocarditis
- C. Libman-Sacks endocarditis
- D. Rheumatic heart disease
Explanation: ***Rheumatic heart disease*** - Characterized by **flat vegetations** on heart valves, known as **Aschoff bodies**, which represent the sequelae of rheumatic fever [1]. - Vegetations in this condition occur due to **non-endothelial attachment**, leading to valve damage and dysfunction . *Rheumatic heart disease* - This is a repeat nd does not provide a different context, hence it is incorrect. - Must include distinguishing clinical features or findings that clearly differentiate it from other listed conditions. *Infective endocarditis* - Characterized by **irregular, bulky vegetations** on valves due to microbial infection, differentiating from the flatter vegetations seen in rheumatic heart disease [1]. - Often associated with **systemic symptoms** such as fever and embolic phenomena, which are not present here. *Non-bacterial thrombotic endocarditis (NBTE)* - Typically presents with **small vegetations** that may also be flat, but are usually found in the context of a malignancy or systemic disease [1]. - These vegetations are primarily **non-infectious**, i.e., not due to current infection, unlike in infective endocarditis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 568. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 566.
Question 9: Which among the following is true about non-bacterial thrombotic endocarditis (NBTE)?
- A. Characterized by small, non-invasive vegetations.
- B. Does not elicit an inflammatory reaction (Correct Answer)
- C. Associated with hypercoagulable states and systemic diseases
- D. Commonly associated with malignancy, especially adenocarcinomas.
Explanation: ***Vegetations elicit inflammatory reaction*** - In non-bacterial thrombotic embolism (NBTE), **vegetations do not provoke a significant inflammatory response** compared to infectious endocarditis. - The vegetations seen in NBTE are typically **non-destructive**, lacking the classic inflammatory signs. *Non invasive in nature* - While NBTE is often associated with underlying malignancy and can present similarly to infective endocarditis, it does not undergo the same **invasive changes**. - This statement is misleading since although the lesions are non-infectious, they can still cause significant **embolic phenomena**. *Thrombi on the leaflets of the cardiac valves* - NBTE is characterized by **sterile vegetations** on heart valves, as opposed to **thrombi**, which are clots formed by platelets and fibrin [1]. - These vegetations attach to **valve surfaces** without causing the same level of damage seen in bacterial endocarditis [1]. *Marantic endocarditis* - This term is often used interchangeably with NBTE, describing the presence of **non-bacterial vegetations** related to states of hypercoagulability, particularly in malignancy. - While NBTE does have marantic features, this oes not accurately depict a false statement about the characteristics of NBTE. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 568.
Question 10: Vegetations on under surface of cusps are found in:
- A. Libman-Sacks endocarditis (Correct Answer)
- B. SABE
- C. Rheumatic fever
- D. Infective endocarditis
Explanation: ***Libman-Sacks endocarditis*** - This condition is characterized by **sterile vegetations** composed of immune complexes and fibrin, typically found on the **undersurface of the mitral and aortic valve cusps**. [1] - It is a prominent cardiac manifestation of **systemic lupus erythematosus (SLE)**. *SABE* - **Subacute bacterial endocarditis (SABE)** refers to infection of an already damaged heart valve, causing slowly progressive vegetations. - While it causes vegetations, they are typically on the **closure line** or ventricular side of the valve, and are not sterile but contain bacteria. [1] *Rheumatic fever* - Acute rheumatic fever causes **small, verrucous vegetations** primarily along the **closure lines of the valve leaflets (especially mitral)**, due to fibrin deposition. [1] - These are caused by an autoimmune reaction to streptococcal infection and are not found on the undersurface of the cusps. *Infective endocarditis* - **Infective endocarditis** involves vegetations formed from thrombus and microorganisms on heart valves, typically on the **atrial surface of the mitral valve** or the **ventricular surface of the aortic valve**. [1] - These vegetations are large and destructive, containing active infection, unlike the sterile vegetations of Libman-Sacks endocarditis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 568.
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