infective endocarditis
Suspect in any bacteraemia with a typical organism (S. aureus, viridans streptococci, S. gallolyticus, E. faecalis, HACEK), a new murmur, emboli, or a prosthetic valve/device. Three blood culture sets before antibiotics, TTE then TEE. Diagnose with Duke-ISCVID 2023. Treatment is 4–6 weeks of bactericidal therapy counted from the first negative culture; partial oral step-down is valid in stable left-sided IE (POET (2019)). Early surgery for heart failure, uncontrolled infection, or embolic risk — decided by an endocarditis team.
initial work-up
- 3 sets of blood cultures from separate venepunctures before antibiotics (stable patient: over ≥30 min; unstable: draw all 3, then treat)
- TTE first in all
- TEE if: TTE negative but suspicion persists, prosthetic valve or intracardiac device, S. aureus with risk features, or TTE positive (to define abscess, perforation, fistula)
- repeat TEE in 5–7 days if initial negative and suspicion remains
- FDG-PET/CT or cardiac CT: prosthetic valve (>3 months post-op) or device IE with equivocal echo; also finds peripheral emboli/metastatic foci
- ECG — new AV block suggests perivalvular abscess (aortic root)
- HIV, HBV, HCV serology in people who inject drugs; dental assessment
diagnostic criteria (ISCVID 2023)
major
| criterion | detail |
|---|---|
| microbiological | typical organism in ≥2 separate cultures (S. aureus, S. lugdunensis, E. faecalis, viridans/S. gallolyticus, HACEK, Granulicatella/Abiotrophia, Gemella, Coxiella/Bartonella by serology/PCR); or non-typical organism persistently positive (≥3 sets) |
| imaging | echo or cardiac CT: vegetation, perforation, aneurysm, abscess, pseudoaneurysm, fistula, new prosthetic dehiscence; or abnormal FDG-PET/CT uptake at a prosthetic valve/device |
| surgical | IE seen at surgery (without histology/micro confirmation) |
minor
- predisposition: prior IE, prosthetic valve, valve repair, congenital heart disease, more-than-mild regurgitation/stenosis, CIED, HOCM, injection drug use
- fever >38.0 °C
- vascular: arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhage, Janeway lesions, cerebral/splenic abscess (incl. imaging-detected)
- immunological: glomerulonephritis, Osler nodes, Roth spots, rheumatoid factor
- microbiological evidence not meeting a major criterion
Definite: 2 major, 1 major + 3 minor, or 5 minor. Possible: 1 major + 1 minor, or 3 minor.
empiric therapy
Only when the patient is unwell before organism identification — otherwise wait for culture results.
| setting | empiric regimen |
|---|---|
| native valve, community-acquired, or late prosthetic valve (>12 months) | vancomycin + ceftriaxone 2 g IV q24h; add ampicillin 2 g IV q4h if enterococcal risk (older, GU/GI source) |
| early prosthetic valve (<12 months) or healthcare-associated | vancomycin + gentamicin, add rifampicin once cultures clear (ID-directed); consider Gram-negative cover (cefepime) |
| people who inject drugs | vancomycin (covers MRSA) ± Gram-negative cover per local epidemiology |
Empiric IE choice depends on local MRSA and Gram-negative resistance rates and on prior patient isolates.
targeted therapy — native valve
Duration counts from the first negative blood culture.
| organism | regimen | duration |
|---|---|---|
| viridans strep / S. gallolyticus, penicillin MIC ≤0.125 mg/L | penicillin G 12–18 MU/day IV or ceftriaxone 2 g IV q24h | 4 weeks (2 weeks + gentamicin in selected uncomplicated NVE) |
| E. faecalis | ampicillin 2 g IV q4h + ceftriaxone 2 g IV q12h | 6 weeks |
| MSSA | cloxacillin 2 g IV q4h or cefazolin 2 g IV q8h | 4–6 weeks |
| MRSA | vancomycin (AUC-guided) or daptomycin 10 mg/kg IV q24h | 6 weeks |
| HACEK | ceftriaxone 2 g IV q24h | 4 weeks |
| right-sided MSSA IE in PWID, uncomplicated | cloxacillin | 2 weeks can suffice |
- prosthetic valve: generally 6 weeks; staphylococcal PVE → cloxacillin/cefazolin (MSSA) or vancomycin (MRSA/CoNS) + rifampicin ≥6 weeks + gentamicin for the first 2 weeks (AHA and ESC)
- ampicillin + ceftriaxone replaces ampicillin + gentamicin for E. faecalis — equal efficacy, far less nephrotoxicity
- S. gallolyticus → colonoscopy (colorectal neoplasia)
- culture-negative IE: prior antibiotics most common cause; send Coxiella and Bartonella serology, consider Tropheryma whipplei PCR on valve tissue
partial oral step-down
POET (2019): stable left-sided IE (streptococci, E. faecalis, S. aureus, CoNS) after ≥10 days IV (and ≥7 days after surgery) → switch to a two-drug oral combination non-inferior for death, embolism, relapse, or unplanned surgery. ESC 2023 endorses partial oral therapy in selected patients.
Eligibility: afebrile, cultures cleared, CRP falling, no abscess on TEE, able to absorb oral therapy. Oral regimens should be ID-directed (e.g. amoxicillin + moxifloxacin/rifampicin; linezolid + fusidic acid/rifampicin).
indications for surgery (ESC 2023, AHA 2015)
| indication | timing |
|---|---|
| heart failure from severe regurgitation, obstruction, or fistula — cardiogenic shock or pulmonary oedema | emergency (<24 h) |
| heart failure without shock | urgent (3–5 days) |
| uncontrolled infection: abscess, pseudoaneurysm, fistula, enlarging vegetation | urgent |
| persistent bacteraemia or fever despite appropriate therapy and source control — >5–7 days (AHA) / >1 week (ESC) | urgent |
| left-sided IE with S. aureus, fungi, or highly resistant organisms (AHA class I) | urgent/elective |
| new heart block, annular/aortic abscess, penetrating lesion | urgent |
| relapsing prosthetic valve IE after completed therapy | urgent/elective |
| vegetation ≥10 mm + embolic event on therapy | urgent |
| vegetation ≥10 mm + severe valve dysfunction, low operative risk | urgent — EASE (2012): surgery <48 h reduced death/embolism |
| vegetation ≥30 mm | urgent |
- infected pacemaker/ICD (lead or device IE) → complete device and lead extraction (AHA class I), even with valve-only involvement
- ischaemic stroke is not a contraindication to surgery unless extensive or comatose
- intracranial haemorrhage → surgery usually delayed ≥4 weeks (endocarditis team)
antithrombotics
- no role for starting aspirin or anticoagulation to reduce embolism
- mechanical valve on warfarin → switch to UFH for flexibility; stop all anticoagulation if intracranial haemorrhage
- thrombolysis contraindicated in septic embolic stroke
prophylaxis
Highest-risk patients only (AHA 2021):
- prosthetic valve, incl. TAVI and prosthetic repair material (annuloplasty rings, chords, clips); VAD (ESC)
- prior IE
- unrepaired cyanotic congenital heart disease; repair with prosthetic material within 6 months; residual defect adjacent to prosthetic material
- cardiac transplant recipients with valvulopathy
Procedures: dental work manipulating gingiva/periapical region or perforating oral mucosa; respiratory procedures incising mucosa (e.g. tonsillectomy). Not for GI, GU, or gynaecological procedures, TOE, or routine cleaning without gingival manipulation.
Regimens (single dose 30–60 min before):
| situation | regimen |
|---|---|
| standard | amoxicillin 2 g PO |
| cannot take PO | ampicillin 2 g IV/IM, or cefazolin/ceftriaxone 1 g IV/IM |
| penicillin allergy without anaphylaxis/angioedema/urticaria | cephalexin 2 g PO |
| penicillin allergy with anaphylaxis/angioedema/urticaria | azithromycin 500 mg or doxycycline 100 mg PO |
Clindamycin is no longer recommended.
traps
- starting antibiotics before 3 blood culture sets → culture-negative IE
- S. aureus bacteraemia without TTE — every adult needs one (Staphylococcus aureus bacteraemia)
- negative TTE ≠ no IE — especially prosthetic valves and small vegetations
- E. faecalis bacteraemia without a clear source → echo (higher IE rate than other enterococci)
- new conduction delay on therapy → aortic root abscess until proven otherwise → TEE
- PWID: addiction medicine/OAT, harm reduction, and HIV/HCV care are part of IE treatment — relapse of injection drives reinfection