Infective Endocarditis
Infection of the endocardial surface (usually valves). Diagnosis requires high clinical suspicion + blood cultures + echo. Delay in treatment = valve destruction, emboli, death. Get cultures before antibiotics -then don't wait.
🔍 Overview
What changed in the 2026 AHA scientific statement (replaces the 2015 statement; consensus suggestions rather than graded recommendations): CHANGED staphylococcal and streptococcal native-valve courses are 4 weeks (staphylococci were 6), E. faecalis is 6 weeks for native and prosthetic valves, and every course is counted from clearance of bacteremia. CHANGED gentamicin is dropped from staphylococcal prosthetic-valve regimens (risk outweighs benefit) and from penicillin-susceptible streptococci; E. faecalis gets ampicillin + ceftriaxone. NEW partial oral therapy after at least 10 days of IV treatment in stable patients (POET), and long-acting dalbavancin or oritavancin when outpatient IV therapy is not possible. NEW surgery, once indicated, is within 48 to 72 hours, delayed 2 to preferably 4 weeks after a hemorrhagic or major ischemic stroke; an endocarditis team decides. UNCHANGED HACEK regimens and durations.
Duke Criteria (use the 2023 Duke-ISCVID version)
Definite IE: 2 major, OR 1 major + 3 minor, OR 5 minor. Possible IE: 1 major + 1 minor, OR 3 minor. Modified Duke, 2000
| Major Criteria | Details |
|---|---|
| 1. Positive blood cultures | Typical organisms in ≥ 2 separate blood culture sets: Viridans strep, S. gallolyticus (bovis), HACEK, S. aureus, or Enterococcus; organisms that only occasionally cause IE need ≥ 3 sets. CHANGED 2023 the old rules on timing (> 12 h apart) and separate venipunctures are no longer required, and coagulase-negative staphylococci count as typical when intracardiac prosthetic material is present. The 2023 criteria also add cardiac CT, FDG-PET/CT and intraoperative findings as major criteria. |
| 2. Endocardial involvement | Echo: vegetation, abscess, new prosthetic dehiscence. OR new valvular regurgitation (murmur change). |
| Minor Criteria |
|---|
| Predisposition: IV drug use, prosthetic valve (including transcatheter), prior IE, structural heart disease, endovascular pacemaker or ICD (the last three clarified in 2023) |
| Fever ≥ 38°C |
| Vascular phenomena: septic emboli, mycotic aneurysm, Janeway lesions, conjunctival hemorrhage |
| Immunologic phenomena: Osler nodes, Roth spots, glomerulonephritis, positive RF |
| Microbiologic: positive cultures not meeting major criteria, or serologic evidence |
Blood Culture Protocol
3 sets of blood cultures from 3 different venipuncture sites before antibiotics. Each set = 1 aerobic + 1 anaerobic bottle. Draw at least 20 mL per set. Space 30–60 min apart if possible (but do NOT delay antibiotics more than 1–2h for critically ill patients).
Organisms
| Organism | % of IE | Key Association |
|---|---|---|
| S. aureus | ~30–40% | Most common overall (especially IVDU and healthcare-associated). Acute, destructive. High embolic risk. |
| Viridans streptococci | ~20–25% | Subacute. Dental procedures. Native valve. More indolent course. |
| Enterococcus | ~10% | GI/GU source. Elderly patients. Requires combination therapy: ampicillin + ceftriaxone (AHA 2026 no longer lists ampicillin + gentamicin, which is more nephrotoxic). Colonoscopy is reasonable, as with S. gallolyticus. |
| Coagulase-negative staph | ~10% | Prosthetic valve IE (especially early < 1 year). S. epidermidis. |
| HACEK organisms | ~3% | Gram-negative, slow-growing. May need prolonged incubation. Treat with ceftriaxone. |
| Culture-negative | ~5–10% | Prior antibiotics (most common reason), Coxiella burnetii (Q fever), Bartonella, Brucella, fungi. |
🚨 Management
Empiric Antibiotic Therapy
| Setting | Empiric Regimen | Notes |
|---|---|---|
| Native valve, acute | Vancomycin (Vancocin) 15–20 mg/kg IV q8–12h + cefepime (Maxipime) 2g IV q8h | Covers MRSA + gram-negatives. Narrow based on cultures. Duration: 4–6 weeks. |
| Native valve, subacute | Vancomycin (Vancocin) + ceftriaxone (Rocephin) 2g IV q24h | Covers strep + staph. If Enterococcus is suspected, add ampicillin: ampicillin + ceftriaxone is the 2026 E. faecalis regimen. Enterococcal Endocarditis Trial, 2013 |
| Prosthetic valve | Vancomycin (Vancocin) + gentamicin + rifampin (Rifadin) 300 mg PO q8h | 6 weeks. Rifampin penetrates biofilm, but start it only after bacteremia clears and 5-7 days of therapy. Once staphylococci grow, stop gentamicin: AHA 2026 found its risk outweighs any benefit in staphylococcal PVE. |
| IVDU (right-sided) | Vancomycin (Vancocin) (covers MRSA -most common in IVDU IE) | Narrow to nafcillin/oxacillin if MSSA. Right-sided (tricuspid) has better prognosis than left-sided. If outpatient IV therapy is not possible (no IV access, unstable housing, active injection drug use), dalbavancin 1500 mg IV on days 1 and 8 after blood cultures clear is a 2026 option DOTS, 2025. POET, 2019 |
🔄 Updated Practice: Old teaching: add gentamicin to all endocarditis regimens for synergy. Current practice: gentamicin is no longer routinely recommended for native valve Staph aureus endocarditis, it adds nephrotoxicity without mortality benefit. For Enterococcus faecalis endocarditis, ampicillin + ceftriaxone is preferred over ampicillin + gentamicin (equally effective, less nephrotoxic, Enterococcal Endocarditis Trial, 2013). The 2026 AHA statement goes further: gentamicin is no longer advised for staphylococcal prosthetic valve endocarditis either (its risk outweighs any benefit), and for streptococci it is kept only for fully penicillin-resistant strains, given with ceftriaxone for the first 2 weeks.
Surgical Indications -When to Operate
Early surgery (during initial hospitalization) reduces mortality in these scenarios: [EASE, 2012
- Heart failure from severe valvular regurgitation -most common surgical indication
- Uncontrolled infection -persistent bacteremia > 5–7 days despite appropriate antibiotics, perivalvular abscess, fistula
- Large vegetation (> 10 mm) with embolic events despite antibiotics
- Fungal endocarditis -almost always requires surgery
- Prosthetic valve endocarditis with dehiscence, abscess, or persistent bacteremia
- S. aureus prosthetic valve IE -consider early surgery regardless
📋 On Rounds
Why does S. bovis endocarditis require a colonoscopy?
S. gallolyticus (formerly S. bovis biotype I) bacteremia/endocarditis has a strong association with colorectal malignancy -up to 25–50% of patients have colon polyps or cancer. The mechanism is thought to involve bacterial translocation through disrupted colonic mucosa. Every patient with S. bovis/gallolyticus bacteremia needs a colonoscopy, even if asymptomatic.
When do you get a TEE vs TTE for endocarditis?
TTE first in most patients -sensitivity ~70% for vegetations. If TTE is negative but clinical suspicion remains high → TEE (sensitivity ~95%). Go straight to TEE in: prosthetic valves (TTE limited by acoustic shadowing), suspected perivalvular abscess, S. aureus bacteremia (high-risk, need definitive imaging), poor TTE windows (obese, ventilated). If initial TTE/TEE negative but suspicion persists → repeat in 5–7 days.
When does endocarditis require surgery instead of antibiotics alone?
Four major surgical indications: (1) Heart failure from valvular regurgitation (most common indication), (2) Uncontrolled infection (persistent bacteremia > 7 days despite appropriate abx, perivalvular abscess, mycotic/fungal endocarditis), (3) Large vegetation (> 10 mm on left-sided valve with embolic event, or > 15 mm even without embolism), (4) Prosthetic valve endocarditis with any of the above.
A patient with IVDU has tricuspid valve endocarditis. Does this change your antibiotic approach?
Right-sided endocarditis (TV) in IVDU has better prognosis than left-sided (mortality ~5% vs ~20-30%). If MSSA: nafcillin/oxacillin 2g IV q4h or cefazolin × 4 weeks from clearance (the 2015 2-week right-sided course is not carried into the 2026 statement). MRSA: vancomycin or daptomycin (daptomycin is an alternative for right-sided MRSA IE, but NOT left-sided -inactivated by surfactant in lungs).
Clinical Examples
📋 Case 1, Native Valve Endocarditis with Embolic Stroke
Patient: 58M with poorly controlled diabetes, presents with 3 weeks of fevers, malaise, and new-onset left arm weakness. Recent dental extraction 4 weeks ago without antibiotic prophylaxis.
Key findings: Temp 38.9°C, HR 105, new aortic regurgitation murmur, Janeway lesions on palms, splinter hemorrhages. Blood cultures 4/4 positive for Streptococcus gallolyticus. TEE: 1.4 cm vegetation on aortic valve with moderate AR. MRI brain: acute embolic infarct R MCA territory.
Management:
- IV penicillin G 4 million units q4h (24 million units/day) or ceftriaxone 2 g daily x 4 weeks; no gentamicin for a penicillin-susceptible strain (AHA 2026)
- Urgent CT surgery consult: large vegetation (>10 mm) + embolic event = surgical indication EASE Trial, 2012
- Colonoscopy required: S. gallolyticus (bovis) has strong association with colorectal neoplasia (~60% have polyps or cancer)
- Serial blood cultures q48h until clearance; repeat TEE at 1 week
Teaching point: S. gallolyticus endocarditis mandates colonoscopy regardless of GI symptoms. Embolic events with vegetations >10 mm warrant early surgery.
📋 Case 2, Prosthetic Valve Endocarditis with Paravalvular Abscess
Patient: 72F with mechanical aortic valve (replaced 8 months ago), presents with fever x 2 weeks, chills, and new heart failure symptoms. Central line placed 3 weeks ago for chemotherapy.
Key findings: Temp 38.5°C, HR 98, BP 100/55, bilateral crackles, JVD. Blood cultures 4/4 positive for methicillin-resistant Staphylococcus epidermidis. TEE: 8 mm vegetation on prosthetic AV, paravalvular abscess with new dehiscence.
Management:
- Vancomycin (AUC-guided) x 6 weeks from clearance, adding rifampin 300 mg PO q8h once blood cultures clear and after 5-7 days; no gentamicin, whose risk outweighs any benefit in staphylococcal PVE (AHA 2026)
- Emergent surgical referral: PVE + paravalvular abscess + heart failure = absolute surgical indication
- Heart failure management: diuresis, preload/afterload optimization while awaiting surgery
- Rifampin added ONLY after blood cultures negative (induces resistance if started during active bacteremia)
Teaching point: PVE with paravalvular abscess has near-100% surgical indication. Rifampin is essential for biofilm penetration on prosthetic material but must be started after culture clearance.
📋 Case 3, Culture-Negative Endocarditis
Patient: 38F, no significant PMH, presents with 6 weeks of fevers, weight loss, arthralgias, and night sweats. Given azithromycin empirically 2 weeks ago at urgent care.
Key findings: Temp 38.2°C, new MR murmur, Osler nodes on fingertips. Blood cultures 4/4 negative (drawn on antibiotics). TTE: 6 mm vegetation on anterior mitral leaflet. Bartonella henselae IgG titer 1:1024. Patient has 3 cats.
Management:
- Culture-negative workup: Bartonella, Coxiella (Q fever) and Brucella serologies, Tropheryma whipplei PCR (HACEK now grow in standard blood cultures, so they are no longer a culture-negative cause)
- Bartonella IE confirmed: doxycycline 100 mg BID plus gentamicin, or plus rifampin when gentamicin cannot be used, with duration guided by ID
- Prior antibiotic exposure is the most common cause of culture-negative IE (~50% of cases)
- Consider 16S rRNA PCR on excised valve tissue if serologies inconclusive
Teaching point: When cultures are negative, always ask about prior antibiotics. Bartonella is the most common cause of culture-negative IE in immunocompetent patients -- think cat exposure.
📣 Sample Presentation
One-Liner
"Mrs. Thompson is a 44-year-old with IVDU presenting with 2 weeks of fever, chills, and a new systolic murmur at the left sternal border. Blood cultures grew MSSA (4/4 bottles). TTE shows a 1.2 cm vegetation on the tricuspid valve."
Key Points to Cover on Rounds
Organism: MSSA on 4/4 blood cultures, sensitive to oxacillin. Antibiotics: nafcillin 2g IV q4h, day 5 of planned 6-week course. Echo: 1.2 cm TV vegetation, moderate TR, no abscess. No embolic complications -CT chest negative for septic emboli, UA clean. Surveillance cultures at 48h negative. ID following. CT surgery evaluated -no surgical indication yet. Plan: PICC line placed, continue IV abx, daily assessment for embolic events.
Monitoring During Treatment
| Parameter | Frequency | Target / Action |
|---|---|---|
| Blood cultures | q24-48h until negative | Must document clearance. Persistent bacteremia → evaluate for abscess, source control |
| Vancomycin trough | Before 4th dose, then 1-2x/week | AUC/MIC-guided dosing preferred. Target AUC 400-600 |
| Gentamicin levels | Peak and trough with first dose | Peak 3-5 mcg/mL (synergy). Trough < 1. Monitor Cr and hearing |
| Renal function | 2-3x/week | Aminoglycosides and vancomycin are nephrotoxic. Adjust doses accordingly |
| CBC, ESR/CRP | Weekly | Trend WBC and inflammatory markers. Should decline with treatment |
| Repeat TTE/TEE | At completion of therapy | New baseline. Sooner if clinical deterioration, new murmur, or concern for abscess |
| Neuro checks | Daily | Embolic stroke in 20-40%. New focal deficit → urgent CT/MRI head |
| ECG | Daily initially | New PR prolongation → perivalvular abscess. New AV block is an emergency |
New conduction abnormality (prolonged PR, new heart block) during IE = abscess until proven otherwise. Get urgent TEE and CT surgery consult.
🧪 Workup
Diagnostic Evaluation -Infective Endocarditis
Blood cultures BEFORE antibiotics. Obtain 3 sets, from separate venipunctures whenever possible; the 2023 Duke-ISCVID criteria dropped the spacing and separate-site requirements, so never delay antibiotics in a septic patient to space them. This is the single most important diagnostic step.
| Test | Findings | Clinical Significance |
|---|---|---|
| Blood cultures ×3 ESSENTIAL | Persistent bacteremia (same organism in multiple sets) | 3 sets BEFORE antibiotics, separate venipunctures when possible. A typical organism in ≥ 2 sets (≥ 3 for nontypical organisms) is a major Duke-ISCVID criterion. Identifies organism + susceptibilities. |
| TTE → TEE | Vegetations, abscess, valve perforation, regurgitation | Start with TTE. If negative but suspicion high → TEE (sensitivity 90-100% vs TTE ~60-75%). TEE mandatory for prosthetic valves. |
| CBC | Leukocytosis, anemia (chronic disease), thrombocytopenia | Anemia of chronic disease common in subacute IE. Thrombocytopenia suggests severe sepsis or DIC. |
| BMP | Cr (baseline + immune complex GN), electrolytes | Renal function -immune complex glomerulonephritis, aminoglycoside toxicity monitoring. |
| ESR / CRP | Elevated | Markers of inflammation. Trend to monitor treatment response. |
| Rheumatoid factor | Elevated in chronic IE | Minor Duke criterion. Immune complex formation in subacute endocarditis. |
| Complement levels (C3/C4) | Low | Consumed by immune complex deposition (glomerulonephritis). |
| Urinalysis | Microscopic hematuria, RBC casts, proteinuria | Immune complex GN or renal septic emboli. Hematuria in up to 50% of IE patients. |
Modified Duke Criteria: Definite IE = 2 major, OR 1 major + 3 minor, OR 5 minor criteria. Major: (1) positive blood cultures (typical organism ×2, or persistently positive), (2) endocardial involvement on echo (vegetation, abscess, new dehiscence, new regurgitation).
💊 Medications
Key Medications -Infective Endocarditis
| Scenario | Regimen | Duration | Notes |
|---|---|---|---|
| Empiric (native valve) | Vancomycin (AUC 400-600) + Ceftriaxone (Rocephin) 2g IV q24h | Pending cultures | Covers MRSA + streptococci + HACEK. Add ampicillin if considering enterococcal coverage (ampicillin + ceftriaxone, AHA 2026). |
| MSSA -native valve | Nafcillin or Oxacillin 2g IV q4h | 4 weeks CHANGED was 6; counted from clearance | Beta-lactams beat vancomycin for MSSA (better outcomes). Cefazolin 2g IV q8h is now an equal first-line option (AHA 2026), not only for penicillin allergy. |
| MRSA -native valve | Vancomycin IV, AUC-guided dosing (target AUC 400-600) | 4 weeks CHANGED was 6; counted from clearance | Trough-based dosing is outdated. AUC-guided dosing reduces nephrotoxicity. Alternatives (AHA 2026): daptomycin 8-12 mg/kg IV daily, ceftaroline 600 mg IV q8h, or linezolid 600 mg q12h (NOT for left-sided endocarditis with pulmonary involvement -inactivated by surfactant). |
| Prosthetic valve (empiric) | Vancomycin + Gentamicin 1 mg/kg IV q8h + Rifampin 300 mg PO q8h | 6 weeks | Rifampin penetrates biofilm on prosthetic material. Do NOT start rifampin until blood cultures are negative and 5-7 days in (resistance develops rapidly). Stop gentamicin once staphylococci grow CHANGED (AHA 2026: risk outweighs benefit). |
| Viridans streptococci (MIC ≤0.12) | Ceftriaxone 2g IV q24h | 4 weeks | Penicillin G 24 million units/day IV (continuous or divided) is the alternative. CHANGED AHA 2026 drops the 2-week ceftriaxone + gentamicin course; intermediate strains get ceftriaxone alone, fully resistant strains (MIC ≥ 4) ceftriaxone + gentamicin for the first 2 weeks or vancomycin. |
| Enterococcus | Ampicillin 2g IV q4h + Ceftriaxone 2g IV q12h | 6 weeks | Ampicillin + ceftriaxone preferred over ampicillin + gentamicin (avoids nephrotoxicity, similar efficacy). If VRE: linezolid or daptomycin. |
Surgical indications: heart failure from valvular dysfunction, uncontrolled infection (persistent bacteremia >5-7 days, abscess, enlarging vegetation), prevention of embolism (vegetation >10 mm with embolic event, >15 mm regardless). Consult CT surgery early.
⚡ Summary
Summary
Modified Duke
2 major, or 1 major + 3 minor, or 5 minor. Major: positive blood cultures (typical organisms), echo vegetation.
Empiric Abx
Vancomycin + ceftriaxone (native valve). Vancomycin + gentamicin + rifampin (prosthetic valve), stopping gentamicin once staphylococci grow and starting rifampin only after clearance. ID consult and endocarditis team always.
Duration
Native valve 4 weeks (staphylococci, streptococci, HACEK) and 6 for E. faecalis; prosthetic valve 6 weeks; all counted from clearance of bacteremia (AHA 2026). Stable patients may finish orally after ≥ 10 days IV (POET).
Surgery
HF from valvular dysfunction, uncontrolled infection, large vegetation (> 10mm) with embolism, abscess.
Must Do
Blood cultures × 3 sets from different sites. TTE first → TEE if negative but suspicion high. CT head if neurologic symptoms.
Source
IVDU = tricuspid. Dental = strep viridans. GI/GU = enterococcus. Prosthetic = coag-neg staph early, S. aureus late.
🧪 Workup
Diagnostic Workup
- Blood cultures × 3 sets BEFORE antibiotics, from separate venipunctures when possible. 20 mL per set (10 mL aerobic + 10 mL anaerobic). Sensitivity > 90% with 3 sets
- CBC: Leukocytosis, anemia (normocytic, chronic disease), thrombocytopenia (if DIC)
- BMP: Cr (renal emboli, drug-induced nephritis), electrolytes
- ESR/CRP: Elevated in > 90%. Useful for monitoring treatment response
- Urinalysis: Microscopic hematuria (renal emboli, immune complex GN) in 25-50%
- RF (rheumatoid factor): Positive in ~50% of subacute IE
- Procalcitonin: Supports bacterial etiology if elevated
Imaging
- TTE first -sensitivity ~75% for native valves. Adequate if high quality and clinical picture clear
- TEE if: TTE negative but high suspicion, prosthetic valve, poor TTE windows, suspected abscess/fistula. Sensitivity ~95%
- CT chest/abdomen/pelvis: If concern for septic emboli (splenic infarct, renal infarct, mycotic aneurysm)
- Brain MRI: If neurologic symptoms. Mycotic aneurysms, septic emboli, meningitis
- PET/CT: Consider for prosthetic valve IE or cardiac implantable device infection when echo is equivocal
Modified Duke Criteria: 2 major, or 1 major + 3 minor, or 5 minor = definite IE. Major = positive blood cultures (typical organism × 2 OR persistently positive) + endocardial involvement on echo (vegetation, abscess, new dehiscence, new regurgitation).
💊 Medications
Antibiotic Therapy
| Organism | Native Valve | Prosthetic Valve | Duration |
|---|---|---|---|
| Empiric (acute) | Vancomycin + cefepime (or gentamicin) | Vancomycin + cefepime, adding rifampin only once staphylococci are confirmed and bacteremia has cleared | Until cultures return |
| MSSA | Nafcillin/oxacillin 2g IV q4h or cefazolin 2g IV q8h | Same + rifampin 300mg PO q8h after clearance; no gentamicin (AHA 2026) | NV: 4 weeks. PV: 6 weeks |
| MRSA | Vancomycin (AUC-guided) OR daptomycin 8-12 mg/kg IV daily | Vancomycin + rifampin after clearance; no gentamicin (AHA 2026) | NV: 4 weeks. PV: 6 weeks |
| Viridans Strep (MIC ≤ 0.12) | Ceftriaxone 2g IV daily OR penicillin G 24 MU/day | Same; no gentamicin for a penicillin-susceptible strain (AHA 2026) | NV: 4 weeks. PV: 6 weeks |
| Enterococcus | Ampicillin 2g IV q4h + ceftriaxone 2g IV q12h (preferred for E. faecalis) | Ampicillin + ceftriaxone 6 weeks | 6 weeks |
| HACEK | Ceftriaxone 2g IV daily | Ceftriaxone 2g IV daily | NV: 4 weeks. PV: 6 weeks |
| Culture-negative | Vancomycin + cefepime. ID consult for serologies (Bartonella, Coxiella, Brucella) | Same + rifampin | 6 weeks |
Key principles: IV therapy until the patient is stable; partial oral therapy (POET) or a long-acting lipoglycopeptide can complete the course in selected patients (AHA 2026). Gentamicin now has a narrow role (enterococcal alternatives and penicillin-resistant streptococci). Monitor vanco troughs, gentamicin levels, renal function. ID consult for all IE.
⚡ Summary
Cultures Before Antibiotics, Then Do Not Wait
Three sets of blood cultures before the first antibiotic dose, from separate venipunctures when possible. Antibiotics given first cause culture-negative endocarditis, which turns a targeted regimen into months of guesswork. In sepsis or acute deterioration, take the cultures fast and start empiric therapy immediately; the 2023 criteria no longer require spacing.
Use the 2023 Duke-ISCVID Criteria
Major: a typical organism in 2 or more blood culture sets, and evidence of endocardial involvement on echo (vegetation, abscess, new dehiscence) or a new regurgitant murmur. Minor: predisposing condition or injection drug use, fever, vascular phenomena, immunologic phenomena, and supportive microbiology. Definite is 2 major, or 1 major plus 3 minor, or 5 minor.
TTE First, but a Negative TTE Does Not Exclude It
Transthoracic echo is the starting point and is quick and non-invasive. TEE is far more sensitive and is required for a prosthetic valve, when abscess is suspected, and whenever suspicion remains after a negative TTE. Going home on a negative TTE with persistent bacteremia is a recognized way to miss this diagnosis.
Let the Organism Tell You Where to Look
S. aureus: acute, aggressive, destroys valves quickly, and is the commonest overall including in injection drug use (classically tricuspid). Viridans streptococci: subacute, after dental procedures. Enterococcus: genitourinary source. S. gallolyticus (bovis): get a colonoscopy, because of its association with colorectal neoplasia. Coagulase-negative staphylococci: prosthetic valves.
Empiric Therapy Then Narrow
Vancomycin plus ceftriaxone for a native valve; vancomycin, gentamicin and rifampin for a prosthetic valve, dropping gentamicin once staphylococci grow. Narrow as soon as susceptibilities return, since targeted therapy is more effective and less toxic. Treat 4 weeks for a native valve (6 for E. faecalis) and 6 for a prosthetic valve, counted from clearance of bacteremia; after valve surgery, give the planned course minus the days already given, with at least 14 days after the operation.
Know the Surgical Indications
Heart failure from valve dysfunction (the commonest and most urgent), perivalvular abscess or heart block, persistent bacteremia beyond 5 to 7 days of appropriate therapy, fungal or highly resistant organisms, recurrent emboli with a persisting large vegetation, and prosthetic valve endocarditis. Refer early rather than after the patient decompensates: operating on established heart failure carries far higher mortality.
Look for Complications Actively
Embolic stroke, mycotic aneurysm, splenic and renal infarcts, vertebral osteomyelitis and septic pulmonary emboli in right-sided disease. Image the brain in any neurologic symptom, and consider whole-body imaging in S. aureus bacteremia. Peripheral stigmata (Janeway lesions, Osler nodes, Roth spots, splinter hemorrhages) are uncommon now, so their absence means nothing.
Get Prophylaxis Right, Because It Narrowed
Only the highest-risk patients need antibiotic prophylaxis: prosthetic valves or prosthetic material, previous endocarditis, certain congenital heart disease, and cardiac transplant valvulopathy. Only for dental procedures involving gingival or periapical manipulation, plus certain respiratory and infected-skin procedures. Mitral valve prolapse and bicuspid aortic valve no longer qualify, and routine GI and GU procedures do not warrant it.
📄 One Pager
Text version
Cardiology / ID · One Pager
Infective Endocarditis
Blood cultures × 3 → empiric abx → echo → ID consult → 4 weeks (native) or 6 (prosthetic, E. faecalis) from clearance, oral completion possible once stable. Surgery if HF, uncontrolled infection, or large vegetation.
Modified Duke Criteria
- 2 major = definite IE
- 1 major + 3 minor = definite IE
- Major: typical organism on ≥ 2 cultures; vegetation/abscess on echo
- Minor: predisposing condition, fever, vascular/immunologic phenomena, positive cultures not meeting major
Management
- Blood cultures × 3 BEFORE antibiotics, separate venipunctures when possible
- Empiric: vancomycin + ceftriaxone (native valve)
- Prosthetic valve: vancomycin + gentamicin + rifampin; stop gentamicin once staphylococci grow, rifampin only after clearance
- TTE first → TEE if negative but high suspicion
- ID consult and endocarditis team always. Duration: 4 weeks native, 6 prosthetic or E. faecalis (AHA 2026)
Surgical Indications
- Heart failure from valvular dysfunction (most common indication)
- Uncontrolled infection (persistent bacteremia > 7 days, abscess)
- Large vegetation > 10mm with embolism EASE, 2012
- Prosthetic valve IE with any of the above
- Fungal endocarditis (almost always requires surgery)
Key Drugs
Vancomycin15-20 mg/kg q8-12h
Ceftriaxone2g IV q12h
Nafcillin2g IV q4h (MSSA)
Gentamicin1 mg/kg q8h (empiric PVE; stop once staphylococci grow)
Pitfalls
- Antibiotics before blood cultures
- Missing perivalvular abscess (need TEE)
- Not consulting surgery early enough
- Not checking for embolic complications (CT head, spleen)