Infective Endocarditis MCQ Questions And Answers

Staphylococcus is the correct answer because it is the most common species of bacteria that causes infective endocarditis. This bacterium is commonly found on the skin and in the nasal passages, making it more likely to enter the bloodstream and infect the heart valves. Staphylococcus can cause severe infections in individuals with weakened immune systems or those who have undergone invasive medical procedures. Helicobacter is primarily associated with gastrointestinal infections, while Bacillus is more commonly associated with food poisoning. Therefore, neither of these bacteria are typically responsible for causing infective endocarditis.

Infective Endocarditis (IE) primarily affects the heart valves, particularly the valve leaflets. The infection typically leads to the formation of vegetations, which are clumps of platelets, fibrin, microorganisms, and inflammatory cells. These vegetations can cause significant damage to the valve leaflets, leading to complications such as valve stenosis or regurgitation. Chordae tendineae, chamber walls, and periprosthetic tissues can also be involved, but the valve leaflets are the most commonly and severely affected.

Infective Endocarditis (IE) primarily affects heart valve leaflets, with vegetation formed from clumps of microorganisms and inflammatory cells. These organisms are metabolically active but do not replicate rapidly, complicating antibiotic treatment. Clinical manifestations arise from the infection, embolization of vegetation fragments, immune responses, and cytokine-induced inflammation. These factors collectively contribute to IE's complex symptoms, necessitating comprehensive management strategies.

Blood cultures positive for typical infective endocarditis organisms is a major criterion for infective endocarditis according to the Duke criteria. This criterion refers to the identification of microorganisms in the blood that are commonly associated with infective endocarditis, such as Streptococcus viridans, Staphylococcus aureus, and Enterococcus species. The presence of these organisms in the blood indicates an active infection involving the heart valves, which is a key diagnostic feature of infective endocarditis. The other options listed, predisposing heart condition or intravenous drug use and immunologic findings such as glomerulonephritis, are not major criteria for diagnosing infective endocarditis.

The Modified Duke Criteria for Infective Endocarditis (IE) are highly sensitive and specific, designed to accurately diagnose IE using a combination of clinical and echocardiographic findings. These criteria classify IE cases into definite, possible, or rejected categories based on major criteria, including typical microorganisms in separate blood cultures and endocardial involvement on echocardiograms, and minor criteria like predisposition and fever. The precision of these criteria ensures effective identification and minimizes false diagnoses, making them essential for managing IE.

True. In children with congenital heart disease (CHD), Group A Streptococci (Streptococcus pyogenes) rarely cause infective endocarditis. While Group A Streptococci can cause various infections, including strep throat and skin infections, it is not a common causative agent for infective endocarditis in individuals with CHD. Infective endocarditis is more commonly associated with other bacteria, such as viridans streptococci or staphylococci, in individuals with underlying heart conditions.

The trial that shows the significant benefit of early surgery in patients at high risk for emboli and with large vegetations is the EASE trial.

In the treatment of Infective Endocarditis (IE), antimicrobial therapy aims to reduce the bacterial load within vegetation to a level manageable by the patient's immune system, rather than achieving complete bacterial eradication. This strategy is necessary because the vegetations have a poor blood supply that impedes antibiotic delivery, and the bacteria present are in a low-growth state, making them inherently less susceptible to antibiotics. Therefore, the objective is to suppress the infection to a point where the body’s immune defenses can effectively control and eliminate the remaining bacteria.

Electrocardiography is effective in diagnosing infective endocarditis in patients with congenital heart disease because it can help identify any abnormal electrical activity in the heart. This can be indicative of an infection in the heart valves, which is a common complication in patients with congenital heart disease. By analyzing the electrical patterns and rhythms of the heart, electrocardiography can provide valuable information to aid in the diagnosis of infective endocarditis.

In the vegetation of Infective Endocarditis (IE), the organisms are typically very active metabolically. This metabolic activity is crucial for their survival and pathogenicity, especially as they produce factors that help them adhere to the valve leaflets and evade the immune system. However, despite their metabolic activity, they do not grow or replicate rapidly within the vegetation. This slow growth is partially due to the limited nutrient supply in the blood and the effects of the host's immune responses, which inhibit replication but not metabolic activity. This characteristic makes treating IE challenging, as the bacteria can be less susceptible to antibiotics due to their slow growth and dormancy-like state in the vegetation.