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# Infective endocarditis

Infective endocarditis is an infection of the heart's inner lining, usually a valve, where growths of germs can destroy it and break off into the blood.

Updated 2026-10-29

## Structures involved

Tap one to see what it is and open it in 3D.

- [Mitral anterior leaflet](https://durgical.com/en/anatomy/anterior-leaflet-of-left-atrioventricular-valve/)
- [Mitral posterior leaflet](https://durgical.com/en/anatomy/posterior-leaflet-of-left-atrioventricular-valve/)
- [Aortic right coronary cusp](https://durgical.com/en/anatomy/right-coronary-leaflet/)
- [Tricuspid anterior leaflet](https://durgical.com/en/anatomy/superior-leaflet-of-right-atrioventricular-valve/)
- [Chordae tendineae](https://durgical.com/en/anatomy/chordae-tendineae-of-right-atrioventricular-valve/)
- [Aortic left coronary cusp](https://durgical.com/en/anatomy/left-coronary-leaflet/)
- [Aortic non-coronary cusp](https://durgical.com/en/anatomy/non-coronary-leaflet-of-aortic-valve/)
- [Tricuspid septal leaflet](https://durgical.com/en/anatomy/septal-leaflet-of-right-atrioventricular-valve/)
- [Valve rings (fibrous skeleton)](https://durgical.com/en/anatomy/fibrous-rings-of-the-heart-valves/)

## Microorganisms that cause it

- [Tropheryma whipplei](https://durgical.com/en/microbiology/tropheryma-whipplei/)
- [Bartonella](https://durgical.com/en/microbiology/bartonella/)
- [Staphylococcus aureus](https://durgical.com/en/microbiology/staphylococcus-aureus/)
- [Staphylococcus epidermidis](https://durgical.com/en/microbiology/staphylococcus-epidermidis/)
- [Viridans streptococci](https://durgical.com/en/microbiology/viridans-streptococci/)
- [Enterococcus](https://durgical.com/en/microbiology/enterococcus/)

## In histology

- [The heart wall, valves and conduction tissue](https://durgical.com/en/histology/the-heart-wall-valves-and-conduction-tissue/)

## In the clinical exam

- [Murmurs: timing, grade, location and radiation](https://durgical.com/en/clinical-exam/murmurs-timing-grade-location-and-radiation/)
- [Digital clubbing and nail signs](https://durgical.com/en/clinical-exam/digital-clubbing-and-nail-signs/)

## In physiology

- [Murmurs and the hemodynamics of valve disease](https://durgical.com/en/physiology/murmurs-and-the-hemodynamics-of-valve-disease/)

## Why it happens

- [Thrombosis and Virchow's triad](https://durgical.com/en/general-pathology/thrombosis-and-virchow-s-triad/)
- [Systemic (arterial) thromboembolism](https://durgical.com/en/general-pathology/systemic-thromboembolism/)
- [Arterial vs venous thrombi; mural thrombi and lines of Zahn](https://durgical.com/en/general-pathology/arterial-vs-venous-thrombi-mural-thrombi-and-lines-of-zahn/)
- [What happens to a thrombus: propagation, embolism, dissolution, organization](https://durgical.com/en/general-pathology/what-happens-to-a-thrombus-propagation-embolism-dissolution-organization/)
- [Fat, air and amniotic fluid embolism](https://durgical.com/en/general-pathology/fat-air-and-amniotic-fluid-embolism/)
- [Drugs of abuse: cocaine, opioids, amphetamines, cannabis](https://durgical.com/en/general-pathology/drugs-of-abuse-cocaine-opioids-amphetamines-cannabis/)

## What it is

Infection of the endocardial surface of the heart, usually a heart valve, forming vegetations of fibrin, platelets and microorganisms that can destroy the valve and break off as emboli.

## Who gets it

Uncommon but serious. In high-income countries it is increasingly linked to prosthetic valves, devices and healthcare contact; in Colombia and Latin America rheumatic valve disease remains an important substrate, and injection drug use adds right-sided cases.

## Causes

- Staphylococcus aureus (most common in many series; acute course)
- Viridans group streptococci (classically subacute, on damaged native valves)
- Enterococci, often after urinary or bowel procedures
- Coagulase-negative staphylococci on prosthetic valves and devices
- HACEK organisms and fungi; culture-negative cases after prior antibiotics

## Risk factors

- Injection drug use (classically tricuspid valve)
- Rheumatic heart disease and other damaged native valves
- Prosthetic valve or intracardiac device
- Previous infective endocarditis
- Congenital heart disease
- Haemodialysis, central lines and poor dental health

## Pathophysiology

Turbulent flow damages the endothelium and a sterile platelet-fibrin deposit forms. Bacteria in the bloodstream adhere to it and multiply, protected from host defences, creating a vegetation. The vegetation erodes the valve, causing regurgitation, can spread to the annulus as an abscess, and sheds septic emboli and immune complexes.

## Classification

- Native vs prosthetic valve vs device-related
- Left-sided vs right-sided (tricuspid, typical in injection drug use)
- Acute (fulminant, often S. aureus) vs subacute (weeks, often streptococci)

## Symptoms and signs

- Fever, sometimes with night sweats, weight loss and fatigue
- New or changing regurgitant murmur
- Splinter haemorrhages and conjunctival petechiae
- Janeway lesions (painless palm and sole macules) and Osler nodes (painful finger pads)
- Roth spots on fundoscopy
- Splenomegaly; septic pulmonary emboli with cough in tricuspid disease

## Red flags

- Acute heart failure from valve destruction
- New neurological deficit (embolic stroke)
- New conduction block on ECG, suggesting annular abscess
- Persistent fever or bacteraemia despite antibiotics
- Large mobile vegetation on echocardiography

## Diagnosis

**Clinical**
Diagnosed with the modified Duke criteria: major criteria are typical organisms in repeated blood cultures and evidence of endocardial involvement on imaging; minor criteria include predisposition, fever, vascular and immunological phenomena.

**Tests**
At least three sets of blood cultures from separate venepunctures before antibiotics; full blood count, inflammatory markers, renal function and urinalysis (haematuria). ECG for conduction changes.

**Imaging**
Transthoracic echocardiography first; transoesophageal echo for prosthetic valves, suspected abscess or a negative but likely case. CT or PET-CT and brain imaging look for emboli and paravalvular spread.

## Differential diagnosis

- Acute rheumatic fever
- Systemic lupus erythematosus
- Atrial myxoma
- Other sources of bacteraemia and sepsis
- Lymphoma or other cause of prolonged fever

## Goal of treatment

Sterilise the vegetation with prolonged bactericidal therapy, repair or replace destroyed valves when needed, and prevent embolic and heart-failure complications.

## Treatment

**Medical**
Prolonged intravenous bactericidal antibiotics chosen by organism and sensitivity (penicillins, glycopeptides and others), usually for several weeks, guided by an endocarditis team.

**Medical**
Empirical antibiotic cover after cultures are taken when the patient is unwell, then narrowed to the cultured organism.

**Surgical**
Valve surgery for heart failure from valve destruction, uncontrolled infection or abscess, or high embolic risk.

**Follow-up**
Repeat blood cultures to confirm clearance, follow-up echocardiography and monitoring for drug toxicity.

**Lifestyle**
Harm-reduction support for people who inject drugs, and attention to dental health.

## Drugs for this condition

- [Ampicillin](https://durgical.com/en/pharmacology/ampicillin/)
- [Cefazolin](https://durgical.com/en/pharmacology/cefazolin/)
- [Cloxacillin](https://durgical.com/en/pharmacology/cloxacillin/)
- [Oxacillin](https://durgical.com/en/pharmacology/oxacillin/)
- [Nafcillin](https://durgical.com/en/pharmacology/nafcillin/)
- [Vancomycin](https://durgical.com/en/pharmacology/vancomycin/)
- [Gentamicin](https://durgical.com/en/pharmacology/gentamicin/)
- [Streptomycin](https://durgical.com/en/pharmacology/streptomycin/)
- [Daptomycin](https://durgical.com/en/pharmacology/daptomycin/)

## Complications

- Heart failure from acute valve regurgitation
- Embolic stroke and brain abscess
- Mycotic aneurysm
- Perivalvular abscess and heart block
- Septic emboli to [spleen](https://durgical.com/en/anatomy/spleen/), [kidneys](https://durgical.com/en/anatomy/kidney/) or lungs
- Immune-complex glomerulonephritis

## Prognosis

Serious even with treatment, with substantial in-hospital mortality. Outcomes are worse with S. aureus, prosthetic valves, heart failure, stroke and older age; early diagnosis and timely surgery improve them. Relapse and recurrence are possible.

## Prevention

- Good oral hygiene and regular dental care in people with valve disease
- Antibiotic prophylaxis before certain dental procedures in high-risk patients, per guidelines
- Careful central line and device care
- Prevention and treatment of streptococcal pharyngitis to limit rheumatic heart disease

## Test yourself

Think of the answer, then tap the question to see it.

## Which criteria are used to diagnose infective endocarditis?

The modified Duke criteria: major (positive blood cultures with typical organisms, imaging evidence of endocardial involvement) and minor criteria.

## Which heart valve is classically affected in people who inject drugs?

The tricuspid valve, often with Staphylococcus aureus and septic pulmonary emboli.

## How do Osler nodes differ from Janeway lesions?

Osler nodes are painful nodules on the finger pads (immunological); Janeway lesions are painless macules on palms and soles (embolic).

## What should be done before starting antibiotics in suspected endocarditis?

Take at least three sets of blood cultures from separate venepunctures.

## What does a new conduction block suggest in aortic valve endocarditis?

Extension of infection into the annulus as a perivalvular abscess, which usually needs surgery.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/infective-endocarditis/)

## Related conditions

- [Rheumatic heart disease](https://durgical.com/en/conditions/rheumatic-heart-disease/)
- [Mitral regurgitation](https://durgical.com/en/conditions/mitral-regurgitation/)
- [Aortic regurgitation](https://durgical.com/en/conditions/aortic-regurgitation/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)
- [Ischaemic stroke](https://durgical.com/en/conditions/ischaemic-stroke/)
- [Ventricular septal defect](https://durgical.com/en/conditions/ventricular-septal-defect/)
- [Tetralogy of Fallot](https://durgical.com/en/conditions/tetralogy-of-fallot/)
- [Systemic lupus erythematosus](https://durgical.com/en/conditions/systemic-lupus-erythematosus/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Infective Endocarditis](https://www.ncbi.nlm.nih.gov/books/NBK557641/) (StatPearls (NCBI Bookshelf), 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/infective-endocarditis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/infective-endocarditis/