Step by Step
Sx
The classic presentation
Suspect endocarditis in any patient presenting with fever plus a new heart murmur — this combination should immediately raise concern for infection of the heart valves, especially in a patient with a known risk factor.
Org
Match the organism to the risk factor
Viridans streptococci (S. mutans, S. sanguinis) follow dental procedures, since these organisms normally live in the mouth. Staphylococcus aureus is the most aggressive cause and is strongly associated with IV drug use (IVDU), where it classically infects the right-sided tricuspid valve rather than the left-sided valves usually affected in other cases. Streptococcus bovis (S. gallolyticus) has a distinctive association with colon cancer — any patient diagnosed with S. bovis endocarditis should be scoped for colon cancer.
Signs
Classic peripheral exam findings
Roth spots are retinal hemorrhages with pale centers, seen on fundoscopic exam. Janeway lesions are painless red macules on the palms and soles. Osler nodes are painful red nodules on the fingers and toes. Splinter hemorrhages appear as thin reddish-brown lines under the nails. A simple memory anchor: Osler nodes are Ouchy (painful); Janeway lesions are painless.
Dx/Rx
Diagnosis and treatment
The Duke criteria are used to formally diagnose endocarditis, combining major criteria (positive blood cultures, evidence of valve involvement on echocardiogram) and minor criteria (fever, vascular/immunologic phenomena, risk factors like IVDU). Empiric treatment before culture results return is typically vancomycin plus ceftriaxone, covering the most likely organisms until specific susceptibilities are known.
Applied Walkthrough
1
A patient with a history of IV drug use presents with fever and a new murmur best heard at the tricuspid valve. This presentation — IVDU plus right-sided valve involvement — points strongly toward Staphylococcus aureus, the most aggressive and classic cause in this population.
2
A different patient recently had a dental procedure and now has fever with a new murmur at the mitral valve. This history points toward viridans streptococci, organisms that normally live in the mouth and can enter the bloodstream during dental work.
3
On exam, the second patient has painless red macules on their palms (Janeway lesions) and painful nodules on their fingertips (Osler nodes) — classic peripheral stigmata of endocarditis.
4
Blood cultures and echocardiogram findings are combined using the Duke criteria to confirm the diagnosis, and empiric vancomycin plus ceftriaxone is started while awaiting final culture and susceptibility results. If this patient's cultures grow Streptococcus bovis instead, that finding alone would prompt a colonoscopy to rule out colon cancer.
Exam Application
Exams test whether you can match the causative organism to the clinical risk factor (viridans strep with dental work, S. aureus with IVDU and right-sided disease, S. bovis with colon cancer), correctly identify the peripheral exam findings, and apply the Duke criteria framework.
⚠ Common Trap
The most common trap is mixing up Janeway lesions and Osler nodes. Use the memory anchor: Osler nodes are "Ouchy" (painful), while Janeway lesions are painless — the two are frequently swapped on exams.
✓ Quick Self-Check
1. What is the classic presentation that should raise suspicion for endocarditis?
Fever plus a new heart murmur.
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2. What organism is classically associated with IV drug use, and which valve does it typically affect?
Staphylococcus aureus; it classically affects the right-sided tricuspid valve.
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3. What organism is associated with recent dental procedures?
Viridans streptococci (such as S. mutans or S. sanguinis).
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4. What condition should be ruled out in a patient with Streptococcus bovis endocarditis?
Colon cancer — these patients should be scoped.
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5. What is the difference between Osler nodes and Janeway lesions?
Osler nodes are painful red nodules on the fingers/toes; Janeway lesions are painless red macules on the palms/soles.
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