Fellow's quick read · Infectious Diseases
Infective endocarditis
AHA Scientific Statement 2015 (Baddour et al), endorsed by IDSA · reviewed 2026-07-27
Personal study digest for a new ID fellow. Recommendations (with ACC/AHA Class of Recommendation / Level of Evidence, e.g. I-B) are from the 2015 AHA/IDSA statement; the 2015 statement is a management document and defers procedural prophylaxis to the AHA prevention statements (2007/2021). The “What’s changed since 2015” section is reviewer synthesis of newer evidence, each claim cited. Not a substitute for the full guideline.
In one line
Endocarditis is a blood-culture + echo diagnosis (modified Duke → now Duke-ISCVID 2023). Get ≥3 blood-culture sets, TTE then TEE, treat with prolonged IV bactericidal therapy by organism, and know the early-surgery triggers: heart failure, uncontrolled infection, and abscess/heart block. ID consult and an Endocarditis Team change outcomes.◆When do I suspect it, and how do I diagnose it?
- Suspect with unexplained bacteremia by a typical organism (viridans strep, S. gallolyticus, S. aureus, enterococci, HACEK), a new regurgitant murmur, embolic/immunologic phenomena, or a prosthetic valve / intracardiac device with fever. S. aureus bacteremia is itself a major Duke criterion — hospital- OR community-acquired.
- Blood cultures: ≥3 sets from separate venipunctures, first and last ≥1 h apart (I-A), before antibiotics whenever possible — prior antibiotics are the leading cause of culture-negative IE.
- Modified Duke criteria classify definite / possible / rejected from major (typical bacteremia; endocardial involvement on echo) and minor (predisposition, fever >38°C, vascular phenomena, immunologic phenomena, suggestive microbiology) criteria. Definite = 2 major, or 1 major + 3 minor, or 5 minor.
- Echo: TTE first in ALL suspected IE (I-B). Go to TEE when TTE is negative/inadequate but suspicion persists, or for a prosthetic valve, possible IE by clinical criteria, or suspected complications (abscess, new AV block) (I-B). Repeat TEE in 3–5 days if the first is negative but suspicion stays high (I-B).
◆Directed therapy by organism — AHA/IDSA 2015; doses assume normal renal function
Principle: prolonged, parenteral, bactericidal therapy. Duration is counted from the first negative blood culture. PVE almost always = 6 weeks. Get an ID consult.
| Organism | Preferred regimen (native valve) | Duration / notes |
|---|---|---|
| Viridans strep / S. gallolyticus (PCN-susceptible, MIC ≤0.12) | Penicillin G 12–18 million U/24h IV or ceftriaxone 2 g IV q24h | 4 wk (IIa-B). A 2-wk course + gentamicin is an option for uncomplicated disease only (no abscess, good renal/8th-nerve function) |
| MSSA | Nafcillin/oxacillin 12 g/24h IV (÷4–6) or cefazolin 6 g/24h IV (÷3) | 6 wk (I). Cefazolin for non-anaphylactoid PCN allergy. Uncomplicated right-sided MSSA = 2 wk |
| MRSA | Vancomycin 30 mg/kg/24h (trough 10–20) or daptomycin ≥8 mg/kg IV daily | 6 wk. Vancomycin is inferior for MSSA — de-escalate to a β-lactam once oxacillin-susceptible |
| Staph — prosthetic valve | Vancomycin (or ASP if MSSA) + rifampin ≥6 wk + gentamicin ×first 2 wk | Rifampin is added only for prosthetic-material staph IE (I-B) |
| Enterococcus (PCN/gent-S) | Ampicillin 2 g IV q4h (or PCN G) + gentamicin, or ampicillin 2 g q4h + ceftriaxone 2 g q12h | NVE 4–6 wk (4 wk if symptoms <3 mo), PVE 6 wk. Double β-lactam if CrCl<50 or high-level gent resistance |
| HACEK | Ceftriaxone 2 g IV q24h | NVE 4 wk, PVE 6 wk (IIa-B). Treat as ampicillin-resistant unless susceptibility confirmed |
| Culture-negative (NVE) | Acute: vancomycin + cefepime; subacute: vancomycin + ampicillin-sulbactam | PVE (early): vancomycin + gentamicin + cefepime + rifampin. Hunt Bartonella, Coxiella, Tropheryma serology/PCR |
| Fungal (Candida/Aspergillus) | Amphotericin B–based induction + valve surgery (I-B) | Then lifelong oral azole suppression (IIa-B). Mortality is high |
- Do NOT add gentamicin to staphylococcal NVE (III-B — toxicity without benefit). Do NOT routinely add rifampin to native-valve staph IE (III-B).
◆When does the fellow escalate to surgery?
Roughly half of IE patients undergo valve surgery during the index admission. Decisions belong to a multidisciplinary team. The three classic buckets (all Class I for left-sided NVE):
- Heart failure from valve dysfunction — the strongest indication (I-B).
- Uncontrolled infection — fungi or highly resistant organisms (VRE, MDR GNR); persistent bacteremia/fever >5–7 days on appropriate antibiotics after excluding other sources (I-B).
- Perivalvular extension — annular/aortic abscess, heart block, fistula, or penetrating lesion (I-B). New AV block has an 88% positive predictive value for abscess — get a TEE.
- Also reasonable (IIa-B): recurrent emboli with persistent/enlarging vegetations, or severe regurgitation + mobile vegetation >10 mm. Embolic risk is highest in the first 2 weeks and falls sharply after — so surgery purely to prevent embolism has the most value early.
◆Key decisions a fellow owns
- Stroke & surgical timing: if valve surgery is indicated and ICH is excluded and neuro damage isn't severe (not comatose), proceed without delay (IIb-B). After a major ischemic stroke or any intracranial hemorrhage, delay surgery ≥4 weeks (IIa-B).
- Anticoagulation: in mechanical-valve IE with a CNS embolic event, stop all anticoagulation for ≥2 weeks (IIa-C). Do NOT start aspirin as adjunctive therapy (III-B); long-standing antiplatelet therapy may be continued if no bleeding.
- Source & foci: remove infected lines/CVCs; image symptomatic metastatic foci; suspect intracranial mycotic aneurysm with focal deficit, severe/localized headache, or “sterile” meningitis (CTA/MRA/DSA).
- Follow-up: baseline TTE at completion; dental evaluation and eradication of oral sepsis; remove the OPAT line at the end; re-culture (≥3 sets) for any new fever rather than blindly re-treating.
What's changed since 2015
Reviewer synthesis of newer evidence — NOT the 2015 guideline. Each claim cited. The 2015 AHA statement remains the current comprehensive US IE document (no newer AHA update through 2026).
- Diagnosis moved on — 2023 Duke-ISCVID criteria supersede modified Duke. New major imaging criteria: cardiac CT (structural lesions) and [18F]FDG-PET/CT (abnormal metabolic activity on a prosthetic valve, graft, CIED, or prosthetic material). Also new: a surgical major criterion (direct inspection at surgery), an expanded “typical organism” list, added predispositions (TAVR/transcatheter valves, CIEDs, prior IE), and removal of the blood-culture timing/separate-venipuncture requirement. Caveat the fellow must know: within 3 months of prosthetic implantation, PET/CT is only a minor criterion (post-op inflammation → false positives). Fowler, Clin Infect Dis 2023;77:518–526; PMID 37138445
- Oral step-down is now evidence-based — POET. In stabilized left-sided IE (strep, E. faecalis, MSSA, CoNS) after ≥10 days IV, switching to oral antibiotics was noninferior to continued IV (6-mo composite 9.0% vs 12.1%). The 2015 text assumes full-course IV; 2023 ESC now endorses partial-oral/OPAT for stabilized, uncomplicated patients. Iversen, N Engl J Med 2019;380:415–424; PMID 30152252
- Enterococcal IE — ampicillin + ceftriaxone is the aminoglycoside-sparing standard. Equal efficacy to ampicillin + gentamicin but far less nephrotoxicity (treatment stopped for adverse events 1% vs 25%), and it works against high-level-gentamicin-resistant E. faecalis. 2015 lists it (IIa-B) mainly for CrCl<50/HLAR; it is now widely first-line. Fernández-Hidalgo, Clin Infect Dis 2013;56:1261–1268; PMID 23392394
- A genuinely new anti-staph agent — ceftobiprole. FDA-approved 3 Apr 2024 for S. aureus bacteremia including right-sided IE (ERADICATE: noninferior to daptomycin, 69.8% vs 68.7%) — an option the 2015 text could not mention. Holland, N Engl J Med 2023;389:1390–1401; PMID 37754204 · RECENCY-SENSITIVE: confirm formulary
- Prophylaxis narrowed and simplified (AHA 2021 + ESC 2023). AHA 2021 reaffirmed 2007: prophylaxis only for the highest-risk cardiac conditions (prosthetic valve/material incl. TAVR, prior IE, certain congenital heart disease, cardiac-transplant valvulopathy) before dental procedures with gingival/periapical manipulation — amoxicillin 2 g PO 30–60 min prior. Clindamycin was removed (C. difficile deaths); doxycycline is now the PCN-allergy option. ESC 2023 strengthened high-risk dental prophylaxis to Class I. Wilson, Circulation 2021;143:e963–e978 · Delgado, Eur Heart J 2023;44:3948–4042
- The Endocarditis Team is now formalized. 2023 ESC mandates a multidisciplinary Endocarditis Team at a Heart Valve Centre for complicated IE — codifying the team approach 2015 only gestured at. Delgado, Eur Heart J 2023;44:3948–4042; doi 10.1093/eurheartj/ehad193
- Still current from 2015: the Duke framework (extended, not discarded); TTE-first→TEE; nafcillin/cefazolin ×6 wk for MSSA and vancomycin/daptomycin for MRSA; no gentamicin and no adjunctive rifampin for native-valve staph IE; the early-surgery triggers (HF, uncontrolled infection, abscess/heart block); and the stroke-timing rules.
◆Anki cards minted this run
2 cards added to Bugs and Drugs Clinicals after a live findNotes dedup (Anki was offline during the run, then reconnected). Tags: Guideline::AHA_IDSA::Endocarditis + Subject::Infectious_Disease.
- Enterococcus faecalis IE, aminoglycoside-sparing regimen → ampicillin + ceftriaxone (double β-lactam); equal efficacy, far less nephrotoxicity, works despite high-level gentamicin resistance.
- Native-valve staph IE → do not add gentamicin or rifampin for synergy (III-B); rifampin is reserved for prosthetic-material staph IE.
Dropped as deck duplicates: POET oral step-down (already carded) and the Duke-ISCVID PET/CT + cardiac CT major-criteria fact (already a pearl on the Duke-criteria card plus five PET/CT cards). Also already in the deck, so not duplicated: cefazolin-first-for-MSSA (SNAP), HACEK→ceftriaxone, and the surgery-indication list.
Sources: Baddour LM, et al. Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications. AHA Scientific Statement, endorsed by IDSA. Circulation 2015;132:1435–1486. doi:10.1161/CIR.0000000000000296. — Currency: Fowler VG, et al. 2023 Duke-ISCVID Criteria. Clin Infect Dis 2023;77:518–526 (PMID 37138445; doi:10.1093/cid/ciad271). Iversen K, et al. POET. N Engl J Med 2019;380:415–424 (PMID 30152252; doi:10.1056/NEJMoa1808312). Fernández-Hidalgo N, et al. Ampicillin+ceftriaxone for E. faecalis IE. Clin Infect Dis 2013;56:1261–1268 (PMID 23392394; doi:10.1093/cid/cit052). Holland TL, et al. ERADICATE (ceftobiprole). N Engl J Med 2023;389:1390–1401 (PMID 37754204; doi:10.1056/NEJMoa2300220). Wilson WR, et al. Prevention of VGS IE (AHA update). Circulation 2021;143:e963–e978 (doi:10.1161/CIR.0000000000000969). Delgado V, et al. 2023 ESC endocarditis guidelines. Eur Heart J 2023;44:3948–4042 (doi:10.1093/eurheartj/ehad193).