INFECTIVE ENDOCARDITIS

✓ Medically ReviewedDISEASEID: MDBT0150🚨 TRIAGE: EMERGENCYICD-10: I33

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Definition

CLINICAL DEFINITION

Infective endocarditis is microbial infection of endocardium (inner heart lining) and valves (heart flaps). Bacteraemia (bacteria in blood) seeds native (own) or prosthetic (artificial) valves to form vegetations (infected clot masses). Staphylococcus aureus (skin germ) causes rapid destruction while oral streptococci (mouth germs) run slower. Diagnosis uses Duke criteria (standard diagnostic rules) with blood cultures (blood germ tests) and echocardiography (heart ultrasound). Emboli (travelling clot bits) and heart failure (weak pump) mark severe disease.

IN PLAIN ENGLISH

Germs in blood stick to heart doors. The clumps grow on the flaps. Bits can fly off and block flows. The doors can leak and fail fast. Long drugs and at times surgery cure it.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Infective endocarditis is not marantic endocarditis (sterile clumps without germs) from cancer or lupus alone. It is not simple bacteraemia (brief blood germs) without vegetation (infected valve mass) on imaging. It is not rheumatic fever (immune reaction after strep throat) alone despite murmurs (abnormal sounds). It is not valve thickening (age change) without cultures and echo evidence.

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Word Breakdown

endo-

=within meaning inner place

card-

=heart meaning pump organ

-itis

=inflammation meaning swelling and injury response

Literal Meaning: inflammation inside the heart lining

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Abbreviations

IE=Infective endocarditis - germ infection of heart valves

NVE=Native valve endocarditis - infection of own valves

PVE=Prosthetic valve endocarditis - infection of artificial valves

IDU-IE=Injection drug use endocarditis - right-sided infection from needle use

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Synonyms & Variants

Bacterial endocarditis›Infectious endocarditis›Endocardial infection›

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Category-Specific Context

Infective endocarditis is a Disease because it is an endovascular infection (vessel-lining germ process) with destruction and spread. It is not a single Sign (exam finding) such as murmur alone. It spans native, prosthetic and right-sided forms with acute and subacute courses. Management joins prolonged antibiotics with timely surgery. It needs Duke workup with emboli and failure watch.

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Clinical Context & Usage

CLINICAL SETTINGS

Emergency Department for Fever with MurmurInpatient Cardiology WardIntensive Care for Heart Failure or ShockCardiac Surgery Centre for Valve ComplicationsAddiction Service for Injection-Related DiseaseEchocardiography Suite for Suspected Vegetation

USAGE & DOCUMENTATION NOTES

Use infective endocarditis for proven or suspected valve infection, not fever alone. Apply Duke criteria (standard rules) using cultures, echo and vascular signs. State valve type such as native, prosthetic or device-related and note organism when grown. Ask about injection use, lines, dental work and devices each visit. Record cultures before antibiotics, echo findings and emboli or failure signs.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Injury or turbulent flow (rough blood movement) exposes valve surface (flap cover) for bacterial sticking. Transient bacteraemia (brief blood germs) seeds the site into vegetation (infected clot mass) of platelets (clotting bits), fibrin (clot threads) and germs. Staphylococcus aureus toxins (germ poisons) drive fast leaflet ruin while streptococci build slower masses. Fragments break as septic emboli (infected travelling bits) to brain, lung and spleen. Local spread forms abscess (pus pocket) with block while leak causes regurgitation (backward flow) and failure.

PRIMARY CAUSES

Staphylococcus aureus bacteraemia

Skin germ in blood seeds valves fast and destroys leaflets with high emboli risk

Viridans streptococci from oral source

Mouth germs after dental work seed prior valve injury slowly causing subacute disease

Enterococcus faecalis in older adults

Gut or urinary germs in blood seed degenerative valves causing persistent bacteraemia

Coagulase-negative staphylococci on prosthetic valves

Implant biofilm (germ slime on artificial material) allows slow indolent infection of replacements

Injection drug use with tricuspid seeding

Repeated needle germ showers seed the right-sided valve causing lung emboli and abscesses

Healthcare contact with lines and devices

Catheter and device biofilm releases germs that stick to injured or artificial valves

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Epidemiology

Prevalence:Endocarditis is uncommon but often fatal without prompt care. Incidence is a few cases per 100000 each year. Prosthetic and device cases are rising with more procedures. Staphylococcus aureus now leads in many centres linked to healthcare contact.

Age Group:Adults over 50 years carry highest burden with degenerative and prosthetic valves. Younger cases cluster with injection use and congenital defects (birth heart flaws). Children are rarely affected except with heart lesions or lines.

Geographic Distribution:Endocarditis occurs worldwide in all regions. Prosthetic and device patterns follow procedure volume. Oral streptococcal patterns persist where rheumatic valve injury (post-strep valve harm) is common. No climate restriction applies because seeding is blood-borne.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 EMERGENCY

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Acute aortic leak with heart failure needing surgery
Perivalvular abscess with new heart block
Large mobile vegetation over 10 mm with emboli
Persistent cultures beyond 72 hours on therapy
Tricuspid disease with lung abscesses in drug use

URGENT EVALUATION TRIGGERS

Fever with new murmur and positive blood cultures
Embolic stroke or limb ischaemia (blocked flow) with fever
Breathlessness with low pressure in suspected valve infection
Persistent bacteraemia beyond 48 to 72 hours on drugs
Chest pain with new block or severe leak murmur

Contraindications & Precautions

CONTRAINDICATIONS

Do not delay blood cultures for antibiotics when endocarditis is suspected
Do not use anticoagulants (clot thinners) to treat vegetation alone without separate indication
Do not start antibiotics before cultures unless shock or severe sepsis forces action
Do not avoid surgery referral when abscess, leak with failure or large mobile mass appears

SPECIAL PRECAUTIONS

Take 3 blood culture sets before antibiotics and note prior doses
Watch daily for failure, emboli, rash and kidney injury
Involve cardiology, infectious diseases and cardiac surgery early
Track echo size with rhythm, renal function and drug levels
Counsel dental hygiene with injection cessation and device review

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Septic emboli (infected travelling clots) to brain, lung or spleen
Heart failure (weak pump) from leaflet destruction and leak
Perivalvular abscess (pus around valve) with conduction block (signal stop)
Stroke (brain injury) and splenic infarct (spleen death)
Glomerulonephritis (kidney filter inflammation) with blood in urine
Persistent bacteraemia (ongoing blood germs) with metastatic abscesses

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Marantic endocarditis

Shares vegetations and murmurs but means sterile clumps from cancer, not germ infection

Pericarditis

Shares chest pain and fever but means outer sac inflammation without valve vegetation

Endocardiosis

Sounds alike but means degenerative thickening without infection or emboli

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Marantic noninfective endocarditis

Key Distinguishing Feature: Sterile vegetations with negative cultures in cancer or lupus without response to antibiotics

Acute rheumatic fever

Key Distinguishing Feature: Migratory joint pain with carditis after strep throat and no vegetations on echo

Uncomplicated bacteraemia

Key Distinguishing Feature: Clear source with fast clearance and no vegetation on transoesophageal echo (throat ultrasound)

Vasculitis

Key Distinguishing Feature: Positive immune markers with glomerular disease but no vegetation on echo

Atrial myxoma with emboli

Key Distinguishing Feature: Mobile tumour mass (benign growth) on echo with negative cultures

Libman-Sacks endocarditis

Key Distinguishing Feature: Small lupus vegetations (immune clumps) with lupus markers and negative cultures

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Clinical Pearls

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Draw 3 blood culture sets before any antibiotics and record prior doses because sterilised cultures hide the cause.

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Image early with transthoracic plus transoesophageal echo and repeat when suspicion stays high.

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Think right-sided disease with lung emboli in injection use and involve addiction care at once.

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Call cardiac surgery early for heart failure, abscess with block or large mobile vegetation over 10 mm.

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Give prolonged organism-led antibiotics with drug-level and kidney checks and book dental review before discharge.

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Example Usage & SOAP

CLINICAL SENTENCE

""38-year-old with fever, murmur and bacteraemia has infective endocarditis.""

IN A SOAP NOTE

S: 38-year-old man with 1-week fever, chills and back ache, injection use history, no chest pain. O: Temp 38.6C, BP 108/62, HR 112, RR 20, SpO2 96 percent on air, new systolic murmur with painful finger nodule. A: Suspected infective endocarditis with bacteraemia. P: Three blood culture sets then empiric antibiotics, transthoracic echo with transoesophageal plan, surgery and addiction consults.

DIFFERENTIAL DIAGNOSIS CONTEXT

Fever with murmur, bacteraemia and vegetation favours infective over marantic endocarditis. Negative cultures with cancer favours marantic disease. Migratory joints after strep favours rheumatic fever. Clear source with fast clearance favours simple bacteraemia. Test cultures with transoesophageal echo.

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Classifications & Scoring

STAGING SCALE

Duke criteria for endocarditis diagnosis

Stages as definite, possible or rejected by major and minor culture, echo and vascular signs to set certainty

STAGING SCALE

Native versus prosthetic and right-sided spectrum

Stages as native, prosthetic, device and right-sided disease by valve and risk to guide drugs and surgery

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Prognosis

SHORT-TERM OUTCOME

Short term death follows heart failure, emboli and aureus virulence (germ aggression). Acute aureus disease of own valves can kill quickly. Early cultures with echo and prompt antibiotics improve survival. Delayed surgery for abscess or leak worsens early outcome.

LONG-TERM PROGNOSIS

Survivors face relapse, valve damage and repeat surgery risk. Prosthetic infection carries higher recurrence and death. Dental hygiene with echo follow-up lowers repeat risk. Addiction care with harm reduction shapes long term course in drug-related cases.

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References & Coding

ICD-10 DIAGNOSTIC CODE

I33

LITERATURE CITATIONS & GUIDELINES

[1]WHO ICD-10 I33 Acute and subacute endocarditis

[2]ESC Guidelines for endocarditis

[3]AHA Scientific Statement on infective endocarditis

[4]Harrisons Principles of Internal Medicine endocarditis

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.