Infective endocarditis: workup and management
Suspect endocarditis with bacteremia from a typical organism, fever with a predisposing valve or device, injection drug use, or embolic events. Diagnose with the 2023 Duke-ISCVID criteria (three blood culture sets before antibiotics, echocardiography, and newer imaging), treat with prolonged bactericidal therapy, and involve an endocarditis team early for surgical decisions.
Working diagnosis
Adult · US guidelines
Draft · awaiting physician review
01Orient
What's new in the evidence
- 2023 Duke-ISCVID criteria: PET/CT, cardiac CT, PCR/sequencing and intraoperative findings count; no timing rule for blood cultures; TAVI and cardiac devices added as predispositions
- POET (2019): switching stable left-sided IE to oral antibiotics after ≥10 days IV was noninferior
- 2023 ESC guideline endorses oral step-down in stabilized patients and early surgery for heart failure, uncontrolled infection or embolic risk
- DOTS (2025): dalbavancin after initial therapy for complicated S. aureus bacteremia had similar efficacy to standard therapy
Differential diagnoses
- Native valve endocarditis (S. aureus, viridans streptococci, enterococci)
- Prosthetic valve or device-related endocarditis (can't miss)
- Right-sided endocarditis with septic pulmonary emboli (injection drug use)
- Culture-negative endocarditis (prior antibiotics, Bartonella, Coxiella, HACEK)
- Nonbacterial thrombotic endocarditis (malignancy, lupus)
- Other causes of persistent bacteremia: line infection, abscess, osteomyelitis
02Assess
Risk scores and decision tools
- 2023 Duke-ISCVID criteria (definite, possible, rejected)
- VIRSTA score to decide on TEE in S. aureus bacteremia
- Surgical risk: EuroSCORE II or STS score
- Embolic risk: vegetation >10 mm, mobile, S. aureus, mitral location
Key history questions
- Fever duration, night sweats, weight loss
- Injection drug use, indwelling lines, hemodialysis
- Prosthetic valve, prior IE, congenital heart disease, cardiac device
- Recent dental or invasive procedure
- Stroke symptoms, back pain, limb or abdominal pain (emboli)
Examination findings
- New or changed regurgitant murmur
- Signs of heart failure
- Splinter hemorrhages, Janeway lesions, Osler nodes, Roth spots, conjunctival petechiae
- Focal neurology, splenomegaly, vertebral tenderness
03Investigate
Initial investigations
- Three sets of blood cultures before antibiotics (stable patients)
- Transthoracic echocardiogram promptly; TEE if TTE negative with ongoing suspicion, prosthetic valve, device, or S. aureus
- CBC, BMP, CRP, urinalysis (hematuria), ECG (new conduction delay suggests abscess)
Advanced investigations
- FDG PET/CT for prosthetic valve or device infection
- Cardiac CT for abscess or pseudoaneurysm
- Brain MRI if neurological symptoms; CT abdomen for emboli
- Serology (Bartonella, Coxiella) and PCR on valve tissue if culture-negative
04Treat
Immediate management
- Unstable or acutely ill: empiric vancomycin plus ceftriaxone (native valve) or plus cefepime/gentamicin for prosthetic valve, after cultures
- Stable patients: wait for culture results before antibiotics when possible
- Acute valve regurgitation with heart failure: emergency surgical consult
First-line treatment
- MSSA: cefazolin 2 g IV every 8 hours or nafcillin/oxacillin
- MRSA: vancomycin (AUC-guided) or daptomycin 8–10 mg/kg/day
- Viridans streptococci: penicillin G or ceftriaxone 2 g daily (4 weeks native)
- Enterococcus faecalis: ampicillin plus ceftriaxone
- Native valve: usually 4–6 weeks; prosthetic valve ≥6 weeks with rifampin (and gentamicin for 2 weeks) for staphylococci
Second-line treatment
- Oral step-down (POET criteria) for stable left-sided IE after ≥10 days IV with clinical response
- Early surgery: heart failure, uncontrolled infection (abscess, persistent bacteremia), fungal or resistant organisms, large vegetation with embolism
- Device infection: complete device removal
Specialist referrals
- Endocarditis team: infectious diseases, cardiology, cardiothoracic surgery
- Addiction medicine for injection drug use (start medication for opioid use disorder)
- Dental evaluation
05Disposition
Admission criteria
- All suspected or confirmed endocarditis
Safe discharge criteria
- Clinically stable, cultures cleared, surgical decisions made
- OPAT or oral step-down plan with weekly labs and ID follow-up
Follow-up timing
- ID clinic every 1–2 weeks during therapy
- Echo at end of therapy
Patient instructions
- Report fever, breathlessness or neurological symptoms immediately
- Dental hygiene and prophylaxis before future dental procedures
Monitoring
- Repeat blood cultures every 24–48 hours until negative
- Weekly CBC, BMP, CK (daptomycin), vancomycin levels
Clinical pearls and pitfalls
- Count antibiotic duration from the first negative blood culture
- Persistent fever after a week suggests abscess, embolic focus or resistant organism
- Injection drug use is not a contraindication to surgery or to oral or long-acting antibiotic options
RefGuidelines and landmark evidence
- Guideline2023 Duke-ISCVID Criteria for Infective EndocarditisPubMed
- GuidelineESC – Guidelines for the Management of Endocarditis (2023)PubMed
- GuidelineAHA – Infective Endocarditis in Adults: Scientific Statement (2015)PubMed
- TrialPOET: partial oral treatment of endocarditis (2019)PubMed
- TrialEASE: early surgery vs conventional treatment for endocarditis (2012)PubMed
For education only. Typical adult starting points; confirm doses against renal function, allergies, interactions and your institution's protocols. Not a substitute for clinical judgment or senior review.