Infective Endocarditis
Also written as IE.
The Duke criteria are used to diagnose infective endocarditis.
Infective Endocarditis
- IV drug users → Tricuspid valve (right-sided)
- Dental procedures → S. viridans → mitral valve
- Signs: Fever, new murmur, Osler nodes (painful, fingers), Janeway lesions (painless, palms/soles), Roth spots (retina), splinter hemorrhages, splenomegaly
Read this in Comprehensive Heart Pathology Notes 🫀
What our notes say
- The Duke criteria are used to diagnose infective endocarditis. (Paediatrics end of second semester exam (MBPE 4300): 4 October 2022, cardiology,)
- An organism that causes acute infective endocarditis is: (Paediatrics end of second semester exam (MBPE 4300): 4 October 2022, cardiology,)
- The most common organism that causes infective endocarditis on a native valve is: (Paediatrics main exam (MBPE 4300): 24 January 2022, Paper One, 100 MCQs, 2 short)
- The following are features of infective endocarditis EXCEPT: (Paediatrics end of 3rd trimester exam (MBPE 4300): 11 January 2022, congenital h)
- Suspected infective endocarditis needs multiple blood cultures before antibiotics, because bacteraemia is continuous and identifying the organism guides therapy. (Cardiology Question Bank: 15 Clinical MCQs)
- A 28-year-old woman is given intravenous penicillin to treat infective endocarditis. (Immunopathology complete mcqs — Past Paper Questions & Answers)
Study material on Infective Endocarditis
- 🫀 VALVULAR HEART DISEASE — ULTRA DEEP NOTES
- Paediatrics main exam (MBPE 4300): 24 January 2022, Paper One, 100 MCQs, 2 short essays and 2 long essays
- Paediatrics end of 3rd trimester exam (MBPE 4300): 11 January 2022, congenital heart disease essay and 20 MCQs
- CARDIOVASCULAR PATHOLOGY
- Junior Clerkship in Internal Medicine (MBIM4100) main exam, Paper One: 31 January 2024
- Paediatrics end of second semester exam (MBPE 4300): 4 October 2022, cardiology, hepatology and gastroenterology, 47 of 50 MCQs
- CARDIOVASCULAR PATHOLOGY
- Cardiovascular system examination revised 2012
- Heart Pathology: Comprehensive Short Notes
- Comprehensive Heart Pathology Notes 🫀
- Cardiovascular syste.m yr 3 — Past Paper Questions & Answers
Practice questions on Infective Endocarditis
48-year-old, infective endocarditis on a previously damaged (rheumatic) valve. Most common cause of subacute bacterial endocarditis?
- Staphylococcus aureus
- Streptococcus viridans (S. sanguinis)
- Enterococcus faecalis
- HACEK organisms
- Staphylococcus epidermidis
Answer: B. - Low-virulence oral streptococci (**viridans group**) classically infect already-damaged/deformed valves → indolent, subacute course - S. aureus causes acute IE, often on **normal** valves ---
A 28-year-old woman is given intravenous penicillin to treat infective endocarditis. Within minutes she develops severe difficulty breathing with respiratory stridor and tachypnea, and an erythematous rash over most of her body. Her symptoms are most likely produced by release of which chemical mediator?
- Interleukin 1
- Bradykinin
- Complement C5a
- Histamine
- Thromboxane
Answer: D. * This is a type I hypersensitivity reaction with systemic anaphylaxis, mediated in part by histamine released from mast cells, causing increased vascular permeability. About 20% of people have some reaction to penicillin or similar drugs, and a minority of these are severe. ---
A 48-year-old male is diagnosed with infective endocarditis. The MOST common cause of subacute bacterial endocarditis on a previously damaged (rheumatic) valve is:
- Staphylococcus aureus
- Streptococcus viridans (Streptococcus sanguinis)
- Enterococcus faecalis
- Staphylococcus epidermidis
- HACEK organisms
Answer: B. *Streptococcus viridans* is the most common cause of subacute infective endocarditis, particularly affecting previously damaged heart valves.
A 68-year-old male develops a fever, new murmur, and splinter hemorrhages 3 weeks after a dental extraction. A TTE reveals a vegetation on the aortic valve. Which of the following peripheral signs is caused by septic emboli from infective endocarditis?
- Osler nodes (painful nodules on finger pads)
- Janeway lesions (painless hemorrhagic macules on palms/soles)
- Roth spots (retinal hemorrhages)
- Splinter hemorrhages
- Clubbing of the fingers ✅ Answer: D
Answer: A. Splinter hemorrhages are linear hemorrhages under the nail bed, caused by microemboli from infective endocarditis lodging in the capillaries.
A patient with infective endocarditis has blood culture showing catalase negative, gram-positive cocci resistant to optochin and not lysed by bile. The organism is
- Enterococcus faecalis
- Staphylococcus epidermidis
- Streptococcus pneumoniae
- Streptococcus pyogenes
- . Enterococci are common causes of subacute endocarditis and UTIs.
Answer: E. Enterococcus is optochin resistant, bile insoluble, and catalase negative, distinguishing it from S. pneumoniae (optochin sensitive, bile soluble). Enterococci are common causes of subacute endocarditis and UTIs. ---
A patient with infective endocarditis has blood culture showing catalase negative, gram-positive cocci resistant to optochin and not lysed by bile. The organism is
- Enterococcus
- Staphylococcus epidermidis
- Streptococcus pneumoniae
- Streptococcus pyogenes
- Primarily an incidental laboratory finding
Answer: A. Enterococcus is optochin resistant and bile insoluble, distinguishing it from S. pneumoniae. ---