What is the difference between acute and subacute infective endocarditis?

Acute infective endocarditis is classically caused by Staphylococcus aureus. It moves fast, is highly destructive, and can seed a previously normal valve. Subacute infective endocarditis is classically caused by viridans group streptococci (such as Streptococcus sanguinis) after dental work. It is indolent and usually settles on a valve that was already abnormal. The shorthand: aureus is the aggressive acute one that attacks normal valves, viridans is the slow subacute one that needs a damaged valve.

How do you tell Janeway lesions from Osler nodes?

Janeway lesions are painless, flat, erythematous macules on the palms and soles, caused by septic emboli (microabscesses). Osler nodes are painful, raised nodules on the pads of the fingers and toes, caused by immune complex deposition. The memory hook: Osler nodes are Ouch-ler nodes because they hurt, and Janeway lesions are painless. Both are minor signs that count as immunologic or vascular phenomena under the Duke criteria.

What are the modified Duke criteria for infective endocarditis?

The modified Duke criteria use two major and several minor criteria. Major criteria are sustained bacteremia with a typical organism on at least two separate blood cultures, and echocardiographic evidence of endocardial involvement such as a vegetation or new valvular regurgitation. Minor criteria are a predisposing heart condition or IV drug use, fever of 38 degrees Celsius or higher, vascular phenomena (Janeway lesions, septic emboli), immunologic phenomena (Osler nodes, Roth spots, glomerulonephritis), and a single positive blood culture that does not meet a major criterion. A definite clinical diagnosis requires 2 major, or 1 major plus 3 minor, or 5 minor criteria.

How is infective endocarditis diagnosed and worked up?

Draw at least three sets of blood cultures from separate venipuncture sites before starting antibiotics. Then obtain a transthoracic echocardiogram (TTE) first, and follow with a transesophageal echocardiogram (TEE) when the TTE is non-diagnostic or when sensitivity matters, such as with prosthetic valves. TEE is more sensitive for vegetations and perivalvular abscess. Empiric therapy is vancomycin, often with the addition of gentamicin and a beta-lactam such as ceftriaxone or cefepime depending on the setting, then narrowed once cultures return.

Who needs endocarditis antibiotic prophylaxis before dental work?

Prophylaxis is reserved for the highest-risk cardiac conditions: a prosthetic heart valve or prosthetic repair material, a history of prior infective endocarditis, unrepaired cyanotic congenital heart disease, and cardiac valvulopathy in a transplanted heart. It is given only before dental procedures that manipulate the gingiva or periapical region or perforate the oral mucosa. Amoxicillin is the standard agent. Routine gastrointestinal and genitourinary procedures no longer warrant prophylaxis.

Cardiology · Infections of the Heart

Infective Endocarditis
Fever, a New Murmur, and a Vegetation

Endocarditis is a pattern, not a list. Fever plus a new or changed murmur plus a risk factor is the whole game. The risk factor tells you the bug, the bug tells you the speed, and the speed tells you which valve and how much damage. Start with the trap that catches the most students.

Medically reviewed by Fatima Ali, DO & Kaitlyn Cocuzzo, MD ✦elite

Before you scroll

A 28-year-old man who injects heroin comes to the emergency department because of five days of fever and shortness of breath. His temperature is 39.1 degrees Celsius. A holosystolic murmur is heard at the lower left sternal border that gets louder with inspiration, and a chest radiograph shows several peripheral nodular opacities. Which of the following valves is most likely involved?

What flag does "injects heroin" raise?

IV drug use sends bugs straight up the venous system to the first valve they hit, the tricuspid. So injection drug use means right-sided endocarditis, almost always tricuspid.

Why does the murmur get louder with inspiration?

Inspiration pulls more blood back to the right heart. A murmur that gets louder on inspiration is a right-sided murmur (Carvallo sign). Left-sided murmurs do the opposite. The holosystolic murmur here is tricuspid regurgitation.

What do the lung nodules tell you?

Pieces of a tricuspid vegetation break off and fly into the lungs (the next thing downstream), giving septic pulmonary emboli seen as peripheral nodular opacities. Right-sided emboli go to the lungs; left-sided emboli go to the brain, kidneys, and spleen. The bug here is classically Staphylococcus aureus.

Scroll ↓ the organism map comes next

The Risk Factor Names the Bug

Match the Setup to the Organism

Almost every endocarditis question hands you a risk factor, then asks for the bug. Memorize this map and the question answers itself. Drag each clinical setup onto its classic organism. Get the bug, and the speed and the valve follow.

Staphylococcus aureus

Acute, destructive, hits even normal valves

Viridans group strep

Subacute, indolent, needs a damaged valve

The other classics

Each setup has its own signature organism

IV drug use, tricuspid valve Acute IE on a previously normal valve Subacute IE after dental work Indolent IE on a rheumatic valve IE plus a screen for colon cancer IE after a urinary or GI procedure Prosthetic valve within 2 months Culture-negative IE

Drag (or tap a setup below, then a column) to map all 8 to their organism. Get them all to unlock the rule.

The map worth burning in

IV drug use → S. aureus, right-sided/tricuspid. Subacute after dental work → viridans strep (S. sanguinis makes dextran that glues it to the valve). Prosthetic valve, early (under 2 months) → coagulase-negative S. epidermidis; late prosthetic → viridans strep. S. gallolyticus (bovis) → go hunt for colon cancer with a colonoscopy. After GU/GI instrumentation → enterococcus. Culture-negative → HACEK organisms, or Coxiella and Bartonella.

The setup is the answer key. Needle = staph. Teeth = viridans. New plastic valve = epidermidis. Gut bug in the blood = look at the colon.

Acute vs Subacute · one fork, two stories

Acute

Bug: Staphylococcus aureus

Speed: days, sick fast, toxic

Valve: can destroy a normal valve

Vegetations: large, bulky, destructive

Subacute

Bug: viridans strep, enterococcus

Speed: weeks, low fevers, weight loss

Valve: needs an already damaged valve

Vegetations: smaller, smolder slowly

Aureus is the brute that kicks down a healthy door. Viridans is the squatter that only moves into a house that was already broken.

From the Attending

Do not start with the valve. Start with the setup. The needle user gives you staph on the tricuspid. The bad teeth give you viridans on a valve that was already scarred. The new prosthetic valve gives you epidermidis. Find the risk factor first, and the organism falls into your lap. That distinction drives everything that comes after it.

Tap to reveal the gallolyticus trap

An older adult with subacute endocarditis and Streptococcus gallolyticus (formerly S. bovis) in the blood needs a colonoscopy, not just antibiotics. The classic teaching: "bovis in the blood means cancer in the colon." The gut tumor lets the organism enter the bloodstream, so finding the bug is also finding the cancer.

The Hands and Eyes Give It Away

Read the Peripheral Stigmata

Endocarditis leaves clues on the skin and in the eye. The clinical medicine live on one split: Janeway is painless, Osler hurts. Tap each finding to reveal why it forms and whether it is septic emboli or immune complexes. Match the photo to the clue.

Janeway lesion: painless erythematous macule on the palm in infective endocarditis — Janeway lesion (painless macule, palm)

Osler nodes: painful violaceous nodules on the finger pads in infective endocarditis — Osler nodes (painful, finger pads)

Splinter hemorrhages: thin linear streaks under the fingernails — Splinter hemorrhages (subungual streaks)

Fundus photograph showing retinal hemorrhages, the appearance seen with Roth spots — Retinal hemorrhages (Roth spots are retinal hemorrhages with a pale center; the pale center defines them but is not always visible in photographs)

Conjunctival hemorrhage of the eye, a vascular phenomenon in endocarditis — Conjunctival hemorrhage / petechiae

Echocardiogram showing a valvular vegetation in infective endocarditis — Vegetation on echocardiogram (the major finding)

🤚

Janeway lesions

Painless

Flat red macules on the palms and soles.

Septic emboli. Tiny chunks of vegetation lodge in skin vessels and seed microabscesses. They are bug fragments, so they are painless and count as a vascular phenomenon (a minor Duke criterion). JaneWAY = aWAY they fly, painless emboli.

Tap to reveal

✋

Osler nodes

Painful

Raised tender bumps on the finger and toe pads.

Immune complexes. Antigen-antibody deposits set off inflammation in the pulp of the digits. Inflammation hurts, so Osler nodes are painful and count as an immunologic phenomenon (a minor Duke criterion). Osler = Ouch-ler.

Tap to reveal

💊

Roth spots

Immune

Retinal hemorrhages with pale centers.

Immune-mediated retinal bleeds. A hemorrhage with a white center on funduscopy. Like Osler nodes, Roth spots are an immunologic phenomenon. Roth = Round red spot, white in the middle.

Tap to reveal

🙋

Splinter hemorrhages

Vascular

Thin red-brown lines under the nails.

Microemboli in the nail bed. They look like a tiny splinter slid under the fingernail. With petechiae and conjunctival hemorrhages, they round out the vascular phenomena. Common but nonspecific, so they support the picture rather than clinch it.

Tap to reveal

The split the writers test every time

Janeway = painless (septic emboli, vascular). Osler = Ouch-ler (immune complexes, immunologic).

Group them by cause and the Duke criteria sort themselves. Vascular phenomena (embolic): Janeway lesions, splinter hemorrhages, conjunctival hemorrhages, septic infarcts, mycotic aneurysm. Immunologic phenomena (immune-complex): Osler nodes, Roth spots, glomerulonephritis. Both are minor Duke criteria, never major.

If it hurts, it is immune (Osler, Ouch-ler). If it is painless, it flew there (Janeway, splinters). Pain sorts the two.

Tap to reveal where left-sided emboli land

Left-sided vegetations throw clots into the systemic circulation: brain (stroke, mycotic aneurysm), kidney (infarct, hematuria), spleen (infarct, left-upper-quadrant pain), and the digits (Janeway, splinters). Right-sided vegetations (IV drug use) throw clots into the lungs instead, giving septic pulmonary emboli. The side of the heart predicts where the damage shows up.

The Signature Game · Build the Diagnosis

The Duke Criteria Builder

The modified Duke criteria decide whether endocarditis is Definite, Possible, or Rejected. Tap the major and minor criteria a patient has and watch the tally light up the verdict. Load a case, or build your own. This is the exact math a stem is asking for.

Major criteria

Minor criteria

Major

Minor

Verdict

Tap criteria to begin

Definite needs 2 major, OR 1 major + 3 minor, OR 5 minor.

The threshold to memorize

Definite = 2 major, OR 1 major + 3 minor, OR 5 minor.

Two major criteria only: positive blood cultures with a typical organism (drawn twice, separate sites), and echo showing a vegetation or new regurgitation. Five minor criteria: a predisposing condition (or IV drug use), fever ≥ 38, vascular phenomena, immunologic phenomena, and a single positive culture. Possible endocarditis is 1 major + 1 minor, or 3 minor. Below that it is rejected.

Two big ones, or one big plus three small, or five small. The vegetation and the cultures are the two majors everything else is minor.

From the Attending

The two majors carry the weight: a real organism growing in the blood twice, and a vegetation you can see on echo. Everything you find on the skin and in the eye, the fever, the murmur on a damaged valve, those are minors. You will almost never count to five minors before the echo or the cultures hand you a major. Get the blood cultures and the echo, and the diagnosis usually makes itself. Know your clues.

From Suspicion to the Operating Room

Diagnose, Treat, Operate, Prevent

Four management questions the clinical medicine ask in order: how do you work it up, what antibiotics, when do you operate, and who gets prophylaxis. Tap a tab. The order of the workup and the surgical triggers are the high-yield lines.

Cultures first · then echo

The Diagnostic Workup

Step 13 sets of blood cultures, separate sites, BEFORE antibiotics

→

Step 2TTE (transthoracic echo) first

→

Step 3TEE if TTE non-diagnostic or prosthetic valve

Cultures

At least 3 sets from separate venipunctures, before any antibiotic

First imaging

TTE (noninvasive, fast)

Most sensitive

TEE (better for vegetations, abscess, prosthetic valves)

Also

ECG to watch for a new AV block (suggests a perivalvular abscess, a pocket of pus burrowing around the valve into the conduction system)

Board trap

Draw cultures BEFORE antibiotics. Starting antibiotics first can sterilize the cultures and erase the major criterion. If the TTE is negative but suspicion stays high, go to TEE, do not stop.

Cultures before drugs. TTE first, TEE when you need sensitivity or there is hardware. New AV block on the ECG means look for an abscess.

Empiric, then narrow

Antibiotic Therapy

Empiric backbone

Vancomycin (covers MRSA while you wait)

Add per setting

Gentamicin and/or ceftriaxone or cefepime

Then

Narrow to a targeted regimen once cultures return

Duration

Long IV course (about 4 to 6 weeks)

Board trap

Start vancomycin empirically because you must cover MRSA before cultures return. Do not wait for sensitivities in a toxic patient. Confirmed viridans strep can be de-escalated to penicillin or ceftriaxone (often with gentamicin to shorten the course).

Empiric is vancomycin (cover MRSA), then add a gram-negative or strep agent by setting, then narrow once cultures speak. Always after the cultures are drawn.

When antibiotics are not enough

Surgical Indications

Heart failure

Valve destruction causing refractory heart failure

Local spread

Perivalvular abscess, valve perforation, or new heart block

Big mobile vegetation

> 10 mm with embolization, or recurrent emboli on therapy

Hard-to-clear bug

Fungal or highly resistant organisms; persistent bacteremia

Board trap

Acute heart failure from a destroyed valve is the most common reason to operate, and it cannot wait for antibiotics to finish. Prosthetic valve dehiscence (the artificial valve tearing loose from its sewn-in seam) also goes to surgery.

Operate for failing pump, abscess/perforation, a big mobile vegetation that keeps throwing clots, or a bug antibiotics cannot clear (fungal, resistant). Heart failure is the number one trigger.

Highest-risk hearts only

Antibiotic Prophylaxis

Who (highest risk)

Prosthetic valve/material, prior IE, unrepaired cyanotic CHD, valvulopathy after a heart transplant

For what

Dental work that manipulates gingiva/periapical tissue or perforates oral mucosa

Drug

Amoxicillin (single dose before the procedure)

NOT for

Routine GI or GU procedures

Board trap

Prophylaxis is narrow on purpose. Only the four highest-risk cardiac conditions qualify, and only for gum-manipulating dental work. A patient with mitral valve prolapse or a bicuspid valve getting a colonoscopy does NOT get prophylaxis.

Only the riskiest hearts (prosthetic valve, prior IE, unrepaired cyanotic CHD, transplant valvulopathy), only for gingiva-manipulating dental work, with amoxicillin. Not for routine GI/GU.

Osteopathic Note · Sympathetics & the OMT contraindication

The cardiac sympathetics run from T1 to T5, so a viscerosomatic reflex from the inflamed heart can show up as tissue texture changes in the upper thoracic spine. But the high-yield osteopathic point here is a contraindication: in active bacteremia or sepsis, lymphatic-pump and other aggressive OMT are generally deferred. Vigorously mobilizing fluid during an active bloodstream infection risks pushing infected emboli into circulation. Treat the infection first; gentle osteopathic care has a role only once the patient is stable.

Cardiac sympathetics = T1 to T5. In active bacteremia, hold the lymphatic pump. Do not pump a patient who is actively septic.

Board Gold · Pattern Recognition

Who Has Endocarditis?

Each round gives one clinical question and four patients. Tap the patients who fit the rule. This is the same pattern recognition the stem is testing, just stripped to its bones.

The unifying theme

The risk factor predicts the bug, the bug predicts the side, and the side predicts where the emboli land.

A needle user with fever and lung nodules is right-sided S. aureus. Bad teeth and a slow burn is left-sided viridans. A new murmur plus a positive culture is endocarditis until echo says otherwise. The reversals to know: mitral valve prolapse and a bicuspid aortic valve are common but do NOT qualify for prophylaxis, and an anaphylactic-level detail never changes the diagnosis, only the drug.

Needle plus lung nodules equals right-sided staph. Teeth plus slow fevers equals left-sided viridans. New murmur plus positive culture equals echo now.

Build the Plan

Walk the Endocarditis Workup

One suspected case, one decision at a time. Guess each branch before it opens. This is the reasoning the exam wants when it asks for the most appropriate next step.

From the Attending

The order is the test. Cultures before antibiotics, because the drugs can erase your proof. TTE first because it is fast and noninvasive, then TEE when you need the sensitivity or there is a prosthetic valve. And surgery the moment the valve fails the pump, because no antibiotic rebuilds a destroyed valve. Get the sequence right and the questions answer themselves. Every time.

Don't Miss The Vegetation

Five Quick Calls

Five rapid questions pulled from a bigger pool, reshuffled every visit. Cross out (right-click / long-press) and highlight (select text) as you read.

clinical Practice

Walk the Cases

Full clinical vignettes, one at a time, in a shuffled order. Progress saves to your account on this device. Cross out (right-click / long-press) and highlight (select text) as you go.

From the Attending

These vignettes are written the way the real exam writes them: a fever and a murmur with one buried discriminator. Cover the choices, find the risk factor, name the organism, then read the options. If you can say the bug out loud, the next step is usually obvious. Read every explanation, not just the one you missed.

Tip: kill the wrong choices first, then read the explanation chain for every option.

References

First Aid for the clinical medicine. Infective endocarditis: organisms, acute vs subacute, peripheral stigmata, modified Duke criteria, prophylaxis.
Modified Duke Criteria. Major and minor criteria for the clinical diagnosis of infective endocarditis (Definite, Possible, Rejected).
American Heart Association. Prevention of Infective Endocarditis. Highest-risk cardiac conditions and dental-procedure prophylaxis with amoxicillin.
Harrison's Principles of Internal Medicine. Infective endocarditis: diagnosis, antimicrobial therapy, and indications for surgery.
Foundations of Osteopathic Medicine. Viscerosomatic reflexes and osteopathic considerations in systemic infection.

Reviewed by Fatima Ali DO and Kaitlyn Cocuzzo MD. Vignettes are original clinical teaching cases; demographics, values, and answer order are written for practice. Always confirm management against the current guideline at the point of care.

Infective EndocarditisFever, a New Murmur, and a Vegetation

Infective Endocarditis
Fever, a New Murmur, and a Vegetation