Infective endocarditis — fellow's quick read

Personal study digest for a new ID fellow. The 2026 AHA statement is a scientific statement (management suggestions by consensus), not a clinical practice guideline with formal Class/LOE grades. It defers procedural prophylaxis to the AHA prevention statements (2007/2021). The 2026 statement introduces a two-phase treatment model (initial IV therapy, then a continuation phase that may include oral step-down or long-acting lipoglycopeptides). Not a substitute for the full statement.

In one line

Endocarditis is a blood-culture + echo + multimodality imaging diagnosis (2023 Duke-ISCVID criteria). Get ≥2 blood-culture sets (timing/venipuncture rules removed), TTE then TEE, consider 18F-FDG-PET/CT and cardiac CT for prosthetic material. Treat with initial IV bactericidal therapy, then consider oral step-down (POET) or long-acting lipoglycopeptides for continuation. Know the early-surgery triggers and the Endocarditis Team model.

◆How do I diagnose it? The 2023 Duke-ISCVID criteria

Suspect with unexplained bacteremia by a typical organism, a new regurgitant murmur, embolic/immunologic phenomena, or prosthetic valve/CIED/TAVR with fever.
Blood cultures: ≥2 sets before antibiotics. The 2023 Duke-ISCVID criteria eliminated the timing and separate-venipuncture requirements. Prior antibiotics and organisms routine culture cannot grow are the two main causes of culture-negative IE.
Expanded “typical organism” list: viridans strep (all except S. pneumoniae and S. pyogenes), S. gallolyticus, S. aureus, E. faecalis (now typical regardless of source/setting), S. lugdunensis, Granulicatella/Abiotrophia, Gemella, HACEK. With prosthetic material add: CoNS, C. striatum/jeikeium, Serratia marcescens, P. aeruginosa, C. acnes, NTM (esp. M. chimaerae), Candida spp.
Definite = 2 major, or 1 major + 3 minor, or 5 minor (unchanged framework). A new surgical major criterion (direct intraoperative inspection) was added.

Imaging beyond echo

Echo: TTE first. Go to TEE when TTE is negative/inadequate and suspicion persists, for prosthetic valves/CIEDs, or for suspected complications. Repeat in 1 week if initial is negative but suspicion stays high.
TEE before oral step-down: obtain within 2 days of transitioning to partial oral therapy, documenting no abscess, no new surgical indication, and vegetation size.
18F-FDG-PET/CT is a major imaging criterion for PVE, CIED, graft infections. Best utility in prosthetic-material IE (>80–90% sensitivity). Low sensitivity in NVE (not generally recommended). Requires 24h ketogenic diet prep when time allows. Caveat: within 3 months of prosthetic implantation, PET/CT is only a minor criterion (post-op inflammation). Also identifies metastatic foci (splenic abscess, vertebral osteomyelitis, septic emboli).
Cardiac CT (CCT): a major criterion. Best for perivalvular/periprosthetic complications (abscess, pseudoaneurysm, dehiscence) when TEE is inconclusive. Superior to TEE for pseudoaneurysm detection. Can also assess coronary arteries preoperatively as an alternative to invasive angiography.
WBC SPECT/CT: an option when PET/CT is unavailable, especially for prosthetic-material infections. More specific for pyogenic infections but lower sensitivity overall.
Brain MRI: superior to CT for neurologic symptoms (ischemic emboli, abscess, mycotic aneurysm). Reasonable preoperatively even in asymptomatic patients requiring cardiac surgery.

Molecular diagnostics

For culture-negative IE: 16S/18S rRNA PCR, metagenomic sequencing, FISH on valve tissue. If cultures are concordant for a typical organism, molecular testing can be deferred.
Store a pre-antibiotic plasma sample for possible later metagenomic sequencing if blood cultures are negative at 72h.
Hunt Bartonella (serology/EIA), Coxiella (phase I/II IgG), Tropheryma whipplei (PCR). See the 2025 AHA BCNE scientific statement.

◆Initial IV therapy by organism — AHA 2026; doses assume normal renal function

The 2026 statement introduces a two-phase model: initial IV induction, then a continuation phase (continued IV, oral step-down per POET criteria, or long-acting injectable lipoglycopeptides). Duration = cumulative pathogen-directed therapy after clearance of bacteremia. NVE typically 4 wk; PVE 6 wk.

Organism	Initial IV therapy	Continuation options / notes
VGS / S. gallolyticus (PCN-susceptible, MIC <0.12)	PCN G 24 million U/24h IV or ceftriaxone 2 g IV q24h	4 wk NVE, ≥6 wk PVE. Oral step-down: amoxicillin 1 g QID + rifampin 600 mg BID, or linezolid + rifampin, or linezolid + moxifloxacin. Lipoglycopeptide: dalbavancin 1500 mg d1 + d8 (or d1 + d15)
VGS / S. gallolyticus (PCN-intermediate, MIC 0.25–2)	Ceftriaxone 2 g IV q24h monotherapy Add gentamicin ×2 wk only if fully PCN-resistant (MIC ≥4)	New: AHA consensus that ceftriaxone monotherapy is acceptable for PCN-intermediate isolates; gentamicin reserved for fully resistant. The MIC-based refinement (ceftriaxone MIC ≤0.5 → ceftriaxone alone; >0.5 → ampicillin + gentamicin ×2 wk) is from the 2025 SPILF position statement the AHA cites, not AHA consensus language
MSSA (native valve)	Nafcillin/oxacillin 12 g/24h IV (÷6) or cefazolin 6 g/24h IV (÷3)	4 wk after clearance of bacteremia (2015: 6 wk). Oral step-down: dicloxacillin 1 g QID + rifampin 600 mg BID, or linezolid + rifampin. Lipoglycopeptide: dalbavancin 1500 mg d1 + d8
MRSA (native valve)	Vancomycin 30 mg/kg/24h IV (÷2) or daptomycin 8–12 mg/kg IV daily or ceftaroline 600 mg IV q8h or linezolid 600 mg IV/PO q12h	4 wk after clearance of bacteremia (2015: 6 wk). Ceftaroline and linezolid are new alternatives. Oral step-down: linezolid + rifampin or linezolid + fusidic acid. Vancomycin is inferior for MSSA: de-escalate to a β-lactam once susceptible
Staph: prosthetic valve	ASP (if MSSA) or vancomycin/daptomycin/ceftaroline/linezolid (if MRSA) + rifampin	6 wk. Consensus: gentamicin risk outweighs any benefit (dropped). No consensus on rifampin (some members omit it). Delay rifampin until bacteremia cleared + 5–7 days of antibiotics
E. faecalis	Ampicillin 2 g IV q4h + ceftriaxone 2 g IV BID (favored by writing group) Alternative: ampicillin + gentamicin	6 wk all cases (NVE and PVE). Ampicillin + ceftriaxone is favored by the writing group (less nephrotoxicity; retains activity against HLAR isolates). Colonoscopy is reasonable (E. faecalis associated with colon neoplasia). Oral: amoxicillin 1 g QID + moxifloxacin 400 mg QD, or linezolid + rifampin
E. faecium (VRE)	Daptomycin 10–12 mg/kg + a β-lactam, or linezolid 600 mg IV/PO BID	6 wk. Dalbavancin lacks VanA activity; oritavancin retains VanA activity. No POET data for VRE
HACEK	Ceftriaxone 2 g IV q24h	NVE 4 wk, PVE 6 wk. Oral step-down: levofloxacin 750 mg QD in select stable patients if susceptible
P. aeruginosa	Cefepime 2 g IV TID or pip-tazo 4.5 g QID or meropenem 1 g TID + tobramycin 8 mg/kg IV daily (peak 15–20, trough ≤2) or a fluoroquinolone	6 wk (NVE and PVE). Gentamicin removed (CLSI breakpoint changes: wild-type P. aeruginosa not treatable with gentamicin). Table 4 lists levofloxacin 750 mg QD as the oral continuation option; some members favor keeping an IV β-lactam + oral FQ in combination
Candida	Amphotericin B lipid 3–5 mg/kg IV QD + flucytosine 25 mg/kg PO q6h or micafungin 150 mg IV q24h	6 wk + surgery. Transition to oral azole after candidemia clearance, clinical improvement, and surgical source control. Non-surgical candidates: long-term suppressive azole. Mortality in fungal PVE >50%
Aspergillus	Voriconazole (load 6 mg/kg IV BID ×2, then 4 mg/kg IV BID) or amphotericin B lipid	6 wk + surgery. Oral azole with Aspergillus activity for suppression. TDM for voriconazole/posaconazole

Do NOT add gentamicin to staphylococcal NVE (toxicity without benefit). Consensus: gentamicin risk outweighs benefit even in staphylococcal PVE (changed from 2015).
Staphylococcal NVE → valve surgery: consensus reached to continue the NVE regimen (monotherapy) post-op; do NOT switch to a PVE combination regimen (adding gentamicin/rifampin increases adverse events without benefit).

◆Oral step-down (POET) and lipoglycopeptides

The 2026 statement endorses partial oral therapy as an option for the continuation phase, not as inferior or second-line therapy.

POET criteria for oral transition

Organisms: streptococci, E. faecalis, MSSA, or CoNS.
≥10 days IV (≥7 days after valve surgery) and clinically stable.
Antimicrobial response: no fever ≥3 days, CRP <25% of peak or <20 mg/L, WBC <15×10⁹/L.
TEE within 2 days of transition: no abscess, no new surgical indication, documented vegetation characteristics.
Exclusions: BMI >40, GI absorption concerns, concomitant infection requiring IV therapy, reduced compliance.

The writing group favors two active oral agents (the POET design). No consensus on dual vs. monotherapy: some members consider monotherapy in select scenarios. The ENDO-ORAL study found no difference with 26% receiving amoxicillin monotherapy.

Long-acting injectable lipoglycopeptides

Dalbavancin: 1500 mg d1 + 1500 mg d8 (DOTS trial; covers ~6 wk), or 1500 mg d1 + d15. Clinical cure 86.9% in one single-center retrospective cohort (n=61, older patients). Consider TDM for longer courses.
Oritavancin: 1200 mg d1 + 1200 mg d8 (or weekly ×2–6 doses). Retains VanA activity (dalbavancin does not). Interferes with aPTT for 120h; unfractionated heparin contraindicated for 5 days post-dose.
Cautions: off-label for IE; relapse rates higher in non-operated PVE (especially E. faecalis, 15%). Case reports of cross-resistance (dalbavancin-, vancomycin-, daptomycin-nonsusceptible S. aureus).

◆When does the fellow escalate to surgery?

Of patients who undergo surgery, roughly 50–60% are operated on during the active phase. Once the indication is established, early surgery within 48–72 hours is favored. Decisions belong to the Endocarditis Team; the final decision to operate rests with the cardiovascular surgeon.

Heart failure from valve dysfunction: the strongest indication.
Uncontrolled infection: fungi or highly resistant organisms; persistent bacteremia/fever >5–7 days on appropriate antibiotics.
Perivalvular extension: abscess, heart block, fistula, perforation.
Large (>1 cm) vegetations threatening embolism, especially with recurrent embolic events. Embolic risk highest in the first 2 weeks.
Right-sided IE: persistent BSI, ongoing septic PE, pulmonary abscess after 7 days of antibiotics, or vegetation >2 cm. Repair preferred over replacement when feasible.
PMA (percutaneous mechanical aspiration): a novel catheter-based option for select patients with right-sided IE and high surgical risk (mostly PWID and CIED patients with tricuspid/lead vegetations). Not widely available; no RCT data yet.

◆Post-surgical antibiotic duration (new guidance)

Recent evidence suggests ≥2 weeks of post-operative antibiotics may be sufficient regardless of valve tissue culture results. Do not “restart the clock” after surgery.
Rule of thumb: complete the planned 4–6 week course, counting preoperative days toward total duration, provided ≥14 days are given post-operatively.
Positive molecular diagnostics (DNA detection on valve tissue) does NOT equal viable organisms and does NOT extend duration.
If therapy completed before surgery with no signs of active infection and negative valve cultures: no additional antibiotics needed.
Metastatic foci (e.g., vertebral osteomyelitis, splenic abscess) may dictate a longer course.

◆Key decisions a fellow owns

Stroke & surgical timing: small strokes without neurologic deficits: surgery can proceed without delay. Hemorrhagic or major ischemic strokes: delay ≥2 weeks, preferably 4 weeks. CT/CTA or MRI/MRA to rule out mycotic aneurysm before proceeding. Cardiac surgery is not appropriate when patients are comatose.
Mechanical thrombectomy: a feasible option for large-vessel occlusion from IE emboli. IV thrombolysis increases mortality 20% due to hemorrhagic complications; MT does not appear to increase hemorrhage.
CIED extraction: in valvular IE, complete device extraction is preferred even without evidence of lead vegetations (2024 AHA CIED statement). Associated with lower 6-month readmission, recurrent bacteremia, and mortality.
Colonoscopy: reasonable in patients with S. gallolyticus or E. faecalis IE (both associated with colon neoplasia).
Follow-up: TTE at end of therapy + 6–12 weeks after valve surgery. Dental evaluation. Remove PICC/OPAT line at completion. Re-culture (≥2 sets) for any new fever.

Suppressive antimicrobial therapy (SAT)

A new section in the 2026 statement. SAT is secondary prevention to decrease relapse risk, not a substitute for surgery when surgery is indicated.

Indications: PVE or CIED IE with an indication for surgery but high operative risk; retained foreign material; limited life expectancy; patient preference. Also fungal IE and mycobacterial IE (often lifelong).
Regimen: pathogen-directed oral agent preferred. IV dalbavancin (500 mg weekly or 1000 mg biweekly) is an alternative.
Breakthrough infection rates remain substantial (7–12.5%) despite SAT.
18F-FDG-PET/CT may help monitor residual infection and guide SAT duration.

What changed: 2015 → 2026

Key differences between the 2015 AHA/IDSA statement (Baddour) and the 2026 AHA statement (DeSimone). The 2026 document supersedes the 2015.

Diagnostic criteria: 2015 used modified Duke (2000). 2026 endorses 2023 Duke-ISCVID: PET/CT, cardiac CT, and intraoperative inspection are now major criteria; expanded typical-organism list; blood-culture timing/venipuncture rules eliminated.
Two-phase treatment: 2015 assumed full-course IV. 2026 explicitly structures initial IV → continuation (continued IV, POET oral step-down, or long-acting lipoglycopeptides).
MRSA alternatives: 2015 listed vancomycin and daptomycin (≥8 mg/kg). 2026 adds ceftaroline 600 mg IV q8h and linezolid 600 mg q12h as alternatives; daptomycin dose range widened to 8–12 mg/kg.
Staphylococcal NVE duration: 2015 said 6 wk for all cases. 2026 Table 1: native valve 4 wk, prosthetic valve 6 wk, counted as cumulative pathogen-directed therapy after clearance of bacteremia.
Enterococcal IE: 2015 stated no preference between ampicillin + gentamicin and ampicillin + ceftriaxone. 2026: ampicillin + ceftriaxone is favored by the writing group; 6 weeks for all cases (NVE and PVE alike).
Staphylococcal PVE: 2015 recommended triple therapy (ASP + rifampin + gentamicin ×2 wk). 2026: consensus that gentamicin is harmful (dropped). No consensus on rifampin (some omit it). Rifampin delay emphasized (not until bacteremia cleared + 5–7 days).
VGS intermediate PCN resistance: 2015 required ceftriaxone + gentamicin ×2 wk. 2026: AHA consensus that ceftriaxone monotherapy is acceptable for PCN-intermediate isolates (the ceftriaxone MIC ≤0.5 refinement is from SPILF 2025, which AHA cites).
Pseudomonal IE: 2015 named "an aminoglycoside" without specifying. 2026: CLSI breakpoint changes eliminated gentamicin as an option; tobramycin is the listed aminoglycoside ( wild-type P. aeruginosa not treatable with gentamicin).
Post-surgical duration: 2015 restarted the clock if valve cultures were positive. 2026: ≥14 days post-op is sufficient; positive molecular diagnostics do not extend duration.
NVE → surgery: 2015 lacked consensus on whether to switch to a PVE regimen post-op. 2026: continue NVE monotherapy (adding gentamicin/rifampin increases harm).
New sections: suppressive antimicrobial therapy, percutaneous mechanical aspiration, TAVR-related IE, mechanical thrombectomy for stroke.
Still current: TTE-first→TEE; nafcillin/cefazolin for MSSA; no gentamicin/rifampin for native-valve staph IE; the core surgery triggers (HF, uncontrolled infection, abscess/heart block); prophylaxis per AHA 2021 (amoxicillin 2 g PO; doxycycline for PCN allergy; clindamycin removed).

Companion AHA IE scientific statements

IE prevention (Wilson, Circulation 2021)
IE in PWID (Circulation 2022)
CIED infections (Circulation 2024)
Blood culture-negative endocarditis (Circulation 2025)
Nondental invasive procedures (science advisory, 2023)
Selected nonvalvular cardiovascular device infections (science advisory, 2026)
PMA in right-sided IE (science advisory, 2026)

◆Anki cards (12 total)

Tags: Guideline::AHA_IDSA::Endocarditis + Subject::Infectious_Disease. Deck: Bugs and Drugs Clinicals.

From the 2015 digest (2026-07-27, updated 2026-09-08)

E. faecalis IE, aminoglycoside-sparing regimen → ampicillin + ceftriaxone (double β-lactam); equal efficacy, far less nephrotoxicity, works despite HLAR. Favored by the AHA 2026 writing group.
Native-valve staph IE → do not add gentamicin or rifampin. For PVE, gentamicin is now dropped (2026); no consensus on rifampin. (Back text updated 2026-09-08.)

New cards from the 2026 AHA update (2026-09-08)

MRSA NVE alternatives → ceftaroline 600 mg IV q8h, linezolid 600 mg q12h; daptomycin 8–12 mg/kg.
POET oral step-down criteria → ≥10d IV, stable vitals/labs, TEE clear; two oral agents favored but no consensus vs monotherapy; organisms limited to strep/E. faecalis/MSSA/CoNS.
Tobramycin for Pseudomonas IE → replaces gentamicin (CLSI breakpoint changes).
Post-op antibiotic duration → don’t restart the clock; ≥14 days post-op; positive PCR on valve tissue does not extend duration.
NVE stays NVE after surgery → continue monotherapy post-op; do not switch to PVE triple therapy.
Staph PVE: gentamicin dropped, rifampin debated → consensus gent risk outweighs benefit; no consensus on rifampin; delay rifampin until BSI cleared + 5–7 days.
VGS intermediate PCN resistance → ceftriaxone monotherapy OK for PCN-intermediate isolates (the MIC ≤0.5 refinement is SPILF, not AHA); gentamicin only for fully resistant (MIC ≥4).
Dalbavancin for IE continuation → 1500 mg d1 + d8 (~6 wk coverage); lacks VanA activity. Oritavancin retains VanA but interferes with aPTT ×5 days.
PET/CT and cardiac CT as major criteria → Duke-ISCVID 2023; PET/CT best for prosthetic IE (>80–90% sens), minor if <3 mo post-implant; CCT best for perivalvular complications.
Staph NVE duration → 4 wk native valve, 6 wk prosthetic (2015: 6 wk for all); counted after clearance of bacteremia.

Sources: DeSimone DC, et al. Infective Endocarditis: Diagnosis, Antibiotic Therapy, and Management. AHA Scientific Statement 2026, endorsed by ISCVID and CCS. Circulation 2026;154:e•••–e•••. doi:10.1161/CIR.0000000000001466. — Predecessor: Baddour LM, et al. AHA/IDSA Scientific Statement 2015. Circulation 2015;132:1435–1486. doi:10.1161/CIR.0000000000000296. — Diagnostic criteria: Fowler VG, et al. 2023 Duke-ISCVID Criteria. Clin Infect Dis 2023;77:518–526 (PMID 37138445; doi:10.1093/cid/ciad271). — POET: Iversen K, et al. N Engl J Med 2019;380:415–424 (PMID 30152252; doi:10.1056/NEJMoa1808312). — DOTS (dalbavancin): Turner NA, et al. Clin Infect Dis 2023 (doi referenced in AHA 2026 Table 1). — ESC 2023: Delgado V, et al. Eur Heart J 2023;44:3948–4042 (doi:10.1093/eurheartj/ehad193). — AHA 2021 IE prevention: Wilson WR, et al. Circulation 2021;143:e963–e978 (doi:10.1161/CIR.0000000000000969).