What is infective endocarditis?

Infective endocarditis (IE) is microbial infection of the endocardial surface — most commonly heart valves, also septal defects, mural endocardium and intracardiac devices (pacemakers, ICDs). Vegetation: a mass of platelets, fibrin, bacteria and inflammatory cells on the valve — the characteristic finding. Presentation: persistent bacteraemia (fever, rigors, malaise), new or changed murmur, embolic phenomena (stroke, pulmonary emboli in right-sided IE, splenic/renal infarction). Mortality: ~20-25%. ~40-50% require cardiac surgery.

What are the most critical IE rules?

(1) Blood cultures BEFORE antibiotics: at least 3 sets from different venepuncture sites, ~1 hour apart, BEFORE starting antibiotics. Antibiotics sterilise cultures within hours. (2) Echo is mandatory: TTE first → TOE if TTE negative, prosthetic valve, intracardiac device, or complications suspected. TOE must be performed for all prosthetic valve IE and all suspected perivalvular complications.

Who gets infective endocarditis?

High-risk groups: Structural heart disease (rheumatic valve disease; prosthetic valves; bicuspid aortic valve; congenital HD). IV drug use (IVDU): right-sided (tricuspid) S. aureus IE; high recurrence. Healthcare-associated IE: bacteraemia from IV lines, dialysis, dental procedures. Prior IE: highest risk for recurrence. Implantable cardiac devices (ICD, pacemaker): lead vegetations. All require preventive dental hygiene and prompt treatment of any bacteraemic infection.

When is surgery needed in IE?

Urgent (24-48h): heart failure from severe acute valve regurgitation/obstruction (most common surgical indication); perivalvular abscess; uncontrolled infection (persistent bacteraemia >7 days; fungal IE; MDR organism). Early (within days): large mobile vegetation >10mm with high embolic risk; prosthetic valve IE with complications; S. aureus prosthetic valve IE.

How does GMJ News cover IE?

GMJ News covers blood cultures before antibiotics (cardinal rule), Modified Duke criteria, S. aureus as dominant pathogen, TTE then TOE echo, urgent surgery indications, HACEK organisms, Osler's/Janeway lesions, S. gallolyticus + colonoscopy, POET oral step-down trial, prophylaxis guidelines (ESC vs NICE), and culture-negative IE work-up.

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Infective Endocarditis

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Infective endocarditis (IE) — microbial infection of the endocardial surface, most commonly involving the heart valves — carries in-hospital mortality of approximately 20-25% despite modern antibiotics and cardiac surgery, and is caused predominantly by Staphylococcus aureus (the most common pathogen globally, particularly in IVDU and healthcare-associated IE) and viridans streptococci (the classic cause of native valve IE following dental procedures) (WHO/ESC). The most critical clinical rule: blood cultures MUST be taken BEFORE antibiotics are started — at least 3 sets from different sites over 1 hour; starting antibiotics before cultures are drawn makes organism identification — and therefore targeted antibiotic therapy for this 4-6 week condition — impossible.

Key messages

Blood cultures BEFORE antibiotics — the cardinal rule

The single most important rule in IE: at least 3 sets of blood cultures from different sites, 1 hour apart, BEFORE starting antibiotics. Antibiotics sterilise cultures within hours — making organism identification impossible for this 4-6 week targeted therapy course. Starting empirical antibiotics before cultures are drawn is a major avoidable error.

Modified Duke criteria — the diagnostic standard

2 major OR 1 major + 3 minor OR 5 minor criteria = definite IE. Major: positive blood cultures (typical organism ×2 or persistent bacteraemia); echocardiographic evidence (vegetation, abscess, new dehiscence of prosthetic valve, new valve regurgitation). Minor: predisposing condition; fever >38°C; vascular phenomena (Janeway lesions, emboli); immunological phenomena (Osler's nodes, Roth's spots, RF, GN); positive culture not meeting major.

S. aureus — most common and most deadly pathogen

S. aureus is now the most common IE pathogen globally — particularly healthcare-associated IE and IVDU (right-sided, tricuspid). S. aureus IE: ~30-40% in-hospital mortality. MRSA: vancomycin or daptomycin. Viridans streptococci: classic community-acquired native valve IE (oral bacteria after dental procedures — indolent, good prognosis). S. gallolyticus (formerly S. bovis): colonic malignancy association — mandates colonoscopy.

Echocardiography — TTE then TOE

TTE: first-line; non-invasive; sensitivity ~50-60% for vegetations. TOE: mandatory if: TTE negative but high suspicion; prosthetic valve; intracardiac device; complications suspected (abscess, fistula). TOE sensitivity ~90-95%. Repeat TOE if initial negative and clinical suspicion remains — vegetations may not form in early IE.

Emergency cardiac surgery — 40-50% of IE patients

Urgent surgery (24-48h): heart failure from severe valvular regurgitation/obstruction (most common indication); perivalvular abscess; uncontrolled infection (persistent bacteraemia ≥7 days; resistant organism; fungal IE). Early surgery (days): mobile vegetation >10mm high embolic risk; prosthetic valve IE with complications; S. aureus prosthetic valve IE.

POET trial — oral step-down therapy is now endorsed

POET trial (NEJM 2019): 400 patients with left-sided NVE or PVE, stable after ≥10 days IV antibiotics → oral step-down non-inferior to continued IV for composite outcome at 6 months. ESC 2023: oral step-down recommended for stable, uncomplicated left-sided IE after initial IV therapy — reducing hospitalisation and IV line complications.

Key statistics

20-25%

in-hospital mortality in infective endocarditis despite treatment

ESC 2023

≥3 cultures

blood culture sets required BEFORE antibiotics from different sites

ESC 2023/AHA

40-50%

of IE patients require cardiac surgery during admission

ESC 2023

S. aureus

most common IE pathogen globally; 30-40% in-hospital mortality

ESC 2023

POET 2019

oral step-down non-inferior to continued IV after initial stabilisation (NEJM 2019)

NEJM 2019

Colonoscopy

mandatory after S. gallolyticus (formerly S. bovis) IE — colonic malignancy association

ESC 2023

Infective endocarditis — microbial causes by clinical setting (ESC 2023)

Source: ESC 2023. S. aureus dominates healthcare/IVDU IE; streptococci in community native valve; culture-negative in ~12%.

Glossary of key terms

Modified Duke criteria
ESC/Li 20002 major OR 1 major + 3 minor OR 5 minor = definite IE. Major: (1) Positive blood cultures: typical organism (viridans streps, S. bovis, HACEK, S. aureus, enterococcus without primary focus) in 2 separate cultures OR persistent bacteraemia >12h apart; (2) Echo evidence: vegetation, abscess, fistula, new prosthetic valve dehiscence, new valvular regurgitation. Minor: predisposing heart disease/IVDU; fever ≥38°C; vascular phenomena; immunological phenomena (Osler's nodes, Roth's spots, RF, GN); culture not meeting major criteria.

TTE vs TOE in IE
ESC 2023TTE first (non-invasive, sensitivity 50-60%). TOE mandatory: any suspected prosthetic valve IE; any CIED-associated IE; any suspected perivalvular complication; high clinical suspicion with negative TTE. TOE sensitivity 90-95%; superior for posterior structures, prosthetic valves, perivalvular extension (abscess, fistula, pseudoaneurysm). Repeat TOE if initial negative and suspicion remains — vegetations may not be visible in early IE.

Osler's nodes and Janeway lesions
Clinical/IEOsler's nodes: painful raised erythematous nodules on finger/toe pads — immune complex deposition. Janeway lesions: non-tender haemorrhagic macules on palms/soles — septic emboli. Roth's spots: oval retinal haemorrhages with pale centres — on fundoscopy. Splinter haemorrhages: subungual linear haemorrhages (non-specific; significant if multiple and distal). All are now uncommon (modern treatment prevents these late manifestations).

HACEK organisms
MicrobiologyFastidious gram-negative bacteria: Haemophilus parainfluenzae, Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae. Part of normal oral flora → indolent endocarditis on damaged valves. Culture-negative IE: consider HACEK (need special media/prolonged incubation); Coxiella burnetii (Q fever — serology); Bartonella (serology); Tropheryma whipplei; fungi.

Antibiotic duration in IE
ESC 2023/AHANVE — Viridans streptococci: 4 weeks (2-week protocol in uncomplicated cases). MSSA NVE: 4-6 weeks flucloxacillin/oxacillin. MRSA NVE: 6 weeks vancomycin. Right-sided S. aureus IVDU: may use 2-week IV protocol if uncomplicated. PVE: minimum 6 weeks. Oral step-down (POET trial): after ≥10 days IV in stable patients — non-inferior to continued IV for left-sided NVE/PVE. ESC 2023 endorses oral step-down.

IE prophylaxis — dental procedures
ESC 2023/NICEESC 2023: prophylaxis only for very high-risk patients: prosthetic valves; previous IE; CHD with unrepaired defects. Not for moderate-risk (acquired valvular disease, MVP, bicuspid aortic valve) — evidence insufficient. NICE (UK): does not recommend for any patient. When given: amoxicillin 2g PO 30-60 min before (clindamycin 600mg if penicillin-allergic). Good dental hygiene is more important than prophylaxis.