Cardiovascular

Infective endocarditis: antibiotic regimens and surgical indications

Clinical Overview and When to Suspect Infective Endocarditis

— Rising incidence driven by injection drug use (IDU), prosthetic valves, intracardiac devices (pacemakers/ICDs), hemodialysis catheters, and an aging population with degenerative valve disease.

— Rheumatic heart disease now a minor contributor domestically; still dominant globally.

— Prosthetic valve (mechanical or bioprosthetic)

— Prior IE (single strongest risk factor)

— Congenital heart disease (unrepaired cyanotic, repaired with residual shunt <6 mo, prosthetic material)

— IDU → right-sided, tricuspid, S. aureus

— Indwelling catheters, hemodialysis, recent dental/GU/GI procedure

— Poor dentition, HIV, diabetes

— Fever + new murmur

— Fever of unknown origin >1 week in at-risk host

— Septic emboli (stroke in young patient, splenic infarct, renal infarct, septic pulmonary emboli)

— Persistent bacteremia despite appropriate antibiotics, especially S. aureus, viridans strep, enterococci, HACEK, or Streptococcus gallolyticus (bovis)

— Glomerulonephritis or unexplained heart failure in a febrile patient

— Acute (days): S. aureus, β-hemolytic strep → toxic, rapid valve destruction

— Subacute (weeks–months): viridans strep, enterococci, HACEK, coag-negative staph on prosthetic valves → indolent, immune phenomena

Board pearl: Any patient with Staphylococcus aureus bacteremia—even with an obvious alternative source—needs echocardiography to rule out IE; S. gallolyticus bacteremia mandates colonoscopy to evaluate for colon cancer. These two reflex moves are perennial Step 3 vignettes.

Infective endocarditis (IE) = microbial infection of the endocardial surface, most often valvular, producing vegetations of platelets, fibrin, and organisms.

Epidemiology shift in the US:

Classic at-risk hosts to flag on the stem:

When to suspect IE (Step 3 trigger phrases):

Acute vs subacute:

Presentation Patterns and Key History

— CNS: stroke, TIA, mycotic aneurysm rupture with SAH, meningitis, brain abscess

— Renal: flank pain, hematuria from infarct

— Splenic: LUQ pain, referred shoulder pain

— Mesenteric: postprandial pain, acute abdomen

— Pulmonary: pleuritic chest pain, hemoptysis, nodular infiltrates → think right-sided IE in IDU

— Peripheral arterial: cold/painful limb

— IDU pattern, shared needles, skin-popping

— Recent dental work, colonoscopy, GU instrumentation, body piercing/tattoo

— Hemodialysis, central lines, chemotherapy ports

— Prior valve repair/replacement, congenital heart repair

— CIED implantation/manipulation

— Prior IE episode

— Recent hospitalization (healthcare-associated IE → MRSA, CoNS)

— Fever + back pain → consider vertebral osteomyelitis/discitis from same bacteremia

— Fever + new heart block → perivalvular/aortic root abscess

— Fever + focal neuro deficit → embolic stroke or mycotic aneurysm

— Fever + new pulmonary nodules in IDU → septic emboli from tricuspid IE

Key distinction: Left-sided IE (mitral/aortic) presents with systemic emboli and heart failure; right-sided IE (tricuspid, IDU-associated) presents with septic pulmonary emboli, pleuritic pain, hemoptysis—murmur may be absent or soft because tricuspid regurgitation is often inaudible. Do not exclude IE because you cannot hear a murmur.

Constitutional prodrome (subacute IE): low-grade fevers, night sweats, anorexia, weight loss, fatigue, arthralgias over weeks—mimics malignancy or rheumatologic disease.

Acute IE: rigors, high fevers, prostration, rapidly progressive heart failure from valve perforation or chordal rupture.

Embolic phenomena (clue-rich for the boards):

Immunologic phenomena: glomerulonephritis (hematuria, RBC casts), arthritis, positive RF.

Targeted history elements:

Red-flag symptom clusters:

Physical Exam Findings and Hemodynamic Assessment

— New or changed regurgitant murmur (MR, AR, TR most common)

— Acute AR: short, soft diastolic murmur; wide pulse pressure; pulmonary edema; Austin Flint rumble

— Acute MR: soft S1, apical systolic murmur, flash pulmonary edema

— TR (right-sided IE): holosystolic at left lower sternal border, increases with inspiration (Carvallo sign); often subtle

— S3 gallop = volume overload/failure

— New conduction abnormality (AV block) on monitor → suspect aortic root abscess

— Janeway lesions: painless erythematous macules on palms/soles → septic emboli

— Osler nodes: painful nodules on finger/toe pads → immune complex (mnemonic: Osler = Ouch)

— Roth spots: retinal hemorrhages with pale centers

— Splinter hemorrhages under nail beds

— Petechiae on conjunctiva, palate, extremities

— Splenomegaly (subacute)

— Clubbing (chronic)

— JVP elevated → RV failure (tricuspid IE) or biventricular failure

— Crackles, S3, hypoxia → acute left-sided regurgitation

— Cool extremities, narrow pulse pressure, oliguria → cardiogenic shock; immediate surgical consult

Step 3 management: A febrile patient with bacteremia who develops new-onset AV block or PR prolongation on telemetry has a perivalvular abscess until proven otherwise—order urgent TEE and consult cardiothoracic surgery, even if hemodynamically stable. This is a high-frequency CCS pivot point.

Vitals: fever (90%), tachycardia, widened pulse pressure if acute AR, hypotension if septic or in cardiogenic shock from acute valvular failure.

Cardiac exam:

Peripheral stigmata (more common in subacute IE; classic Step 3 buzz phrases):

Hemodynamic assessment:

Neuro exam: focal deficits suggest embolic stroke; nuchal rigidity suggests meningitis or mycotic aneurysm rupture.

MSK: vertebral tenderness → concomitant osteomyelitis.

Diagnostic Workup — Initial Labs, Imaging, ECG, Biomarkers

— Obtain 3 sets from separate venipuncture sites, ≥1 hour apart, before antibiotics whenever clinically feasible.

— If patient is septic/unstable: draw 2–3 sets within minutes, then start empiric therapy—do not delay antibiotics for serial cultures in shock.

— Hold antibiotics for 48 hours in stable subacute presentations if prior antibiotics may be obscuring culture yield (when feasible).

— CBC: leukocytosis with left shift (acute) or normocytic anemia (subacute)

— ESR, CRP elevated (nonspecific but supportive)

— BMP: AKI from emboli, GN, or sepsis

— UA: hematuria, RBC casts, proteinuria → immune complex GN

— LFTs, lactate, coags

— Procalcitonin (adjunct, not diagnostic)

— RF positive in ~50% of subacute IE

— HIV testing in IDU

— Baseline rhythm

— New PR prolongation, AV block, BBB → think aortic root/perivalvular abscess

— Ischemic changes from coronary embolization

— CXR: pulmonary edema (left-sided), septic emboli/nodules with cavitation (right-sided)

— CT chest if pulmonary septic emboli suspected

— TTE first in all suspected IE: assesses vegetations ≥3–5 mm, valve function, EF, pericardial effusion

— Sensitivity ~70% native valve, much lower in prosthetic or obese/COPD patients

— Major: typical organism in 2 separate cultures OR persistent bacteremia; echo evidence (vegetation, abscess, new dehiscence) or new regurgitation

— Minor: predisposition, fever ≥38°C, vascular phenomena, immunologic phenomena, suggestive microbiology

Board pearl: A negative TTE does not exclude IE—if clinical suspicion remains, proceed directly to TEE. Always TEE for prosthetic valves, suspected perivalvular abscess, CIED-related IE, or persistent S. aureus bacteremia.

Blood cultures are the cornerstone:

Routine labs:

ECG:

Chest imaging:

Bedside echocardiography:

Modified Duke Criteria (definite IE = 2 major, or 1 major + 3 minor, or 5 minor):

Diagnostic Workup — Advanced and Confirmatory Studies

— Sensitivity >90% for vegetations, ~90% for abscess

— Mandatory for: prosthetic valves, intracardiac devices, suspected complication (abscess, fistula, leaflet perforation, dehiscence), inconclusive TTE with persistent clinical suspicion

— Repeat TEE in 5–7 days if initial negative but suspicion remains high

— Repeat TEE after 1–2 weeks of therapy if clinical deterioration, persistent bacteremia, or new murmur

— Causes: prior antibiotics, fastidious organisms (HACEK—now usually culture-positive in modern systems), Coxiella burnetii (Q fever, livestock/farm exposure), Bartonella (homeless, cat exposure), Brucella, Tropheryma whipplei, Legionella, fungi

— Send serologies: Coxiella phase I IgG, Bartonella IgG, Brucella, Legionella urine antigen

— Marantic (NBTE): malignancy-associated; Libman-Sacks: SLE—obtain ANA, antiphospholipid antibodies

— Consider 16S rRNA PCR on excised valve tissue

— Cardiac CT angiography: defines perivalvular extension, abscess, pseudoaneurysm

— 18F-FDG PET/CT: helpful >3 months post-valve surgery; counts as a Duke major criterion in prosthetic valve IE per 2023 Duke-ISCVID revision

— Brain MRI: identifies silent emboli/mycotic aneurysms—influences surgical timing

— CT abdomen/pelvis: splenic, renal, mesenteric infarcts/abscesses

— Cerebral CTA/MRA: mycotic aneurysm if focal neuro signs or before anticoagulation decisions

— S. gallolyticus → colonoscopy for colorectal neoplasia

— Enterococcus → GU source workup, consider colon source

— Candida → fundoscopy for endophthalmitis, remove indwelling lines

CCS pearl: In suspected IE with stroke, brain MRI changes management—large infarcts or hemorrhagic conversion may delay valve surgery 2–4 weeks; small ischemic emboli without hemorrhage do not preclude urgent surgery.

Transesophageal echocardiography (TEE):

Culture-negative endocarditis (~10%):

Advanced imaging (especially prosthetic valve/CIED IE):

Other workups triggered by organism:

Risk Stratification and First-Line Management Logic

— Admit all suspected IE to inpatient telemetry minimum

— ICU if: septic shock, acute pulmonary edema, AV block, large mobile vegetation with stroke, hemodynamic instability

— Early multidisciplinary "Endocarditis Team": cardiology, cardiothoracic surgery, infectious disease (ID); shown to reduce mortality

— Acute/septic presentation: start empiric therapy immediately after 2–3 blood cultures drawn

— Stable subacute presentation: consider waiting 24–48 hours for cultures to optimize organism identification

— Native valve, community-acquired:

— Vancomycin + ceftriaxone (covers MRSA, MSSA, streptococci, enterococci, HACEK)

— Or ampicillin-sulbactam + gentamicin if MRSA risk low

— Native valve, IDU or healthcare-associated (MRSA risk):

— Vancomycin + cefepime or piperacillin-tazobactam (cover Pseudomonas in IDU)

— Prosthetic valve, early (<12 months post-op):

— Vancomycin + gentamicin + cefepime + rifampin (cover MRSA, CoNS, gram-negatives)

— Prosthetic valve, late (>12 months):

— Same as native valve regimen, often with vancomycin

— Remove infected catheters, ports, pacemaker/ICD leads when implicated

— Drain abscesses (splenic, vertebral, paravertebral)

— Treat dental caries/periodontal disease before valve surgery when feasible

— S. aureus, fungal, or MDR organism

— Heart failure from valve dysfunction

— Perivalvular extension/abscess

— Persistent bacteremia >5–7 days on appropriate therapy

— Large (>10 mm) mobile vegetation, especially with embolic event

— Prosthetic valve IE

Step 3 management: Always draw blood cultures first, then start empiric IV antibiotics, then arrange TTE within hours—do not wait days for echo before starting therapy in a septic patient. Antibiotics typically run 6 weeks from the first negative blood culture.

Initial triage decisions (CCS workflow):

Empiric antibiotic timing:

Empiric regimen selection (before culture data):

Source control priorities:

Risk factors predicting poor outcome / early surgery need:

Pharmacotherapy — Pathogen-Directed Regimens

— Penicillin G or ceftriaxone × 4 weeks (native valve)

— Or PCN/ceftriaxone + gentamicin × 2 weeks (short course, native valve only, no complications)

— Prosthetic valve: 6 weeks of PCN/ceftriaxone ± 2 weeks gentamicin

— PCN-allergic: vancomycin × 4 weeks

— Penicillin G × 4 weeks + gentamicin × 2 weeks

— MSSA: nafcillin or oxacillin × 6 weeks (cefazolin if mild PCN allergy)

— MRSA: vancomycin × 6 weeks (target AUC/MIC 400–600) or daptomycin (≥8 mg/kg) if vancomycin intolerance

— Right-sided uncomplicated MSSA IE in IDU: 2-week short course of nafcillin + gentamicin acceptable in select cases (small vegetation, no emboli, no left-sided involvement)

— MSSA: nafcillin + rifampin × ≥6 weeks + gentamicin × 2 weeks

— MRSA: vancomycin + rifampin × ≥6 weeks + gentamicin × 2 weeks

— Rifampin is added after bacteremia clears to avoid resistance

— Ampicillin + ceftriaxone × 6 weeks (preferred, less nephrotoxic than gent)

— Or ampicillin + gentamicin × 4–6 weeks

— Vancomycin-resistant (VRE): daptomycin or linezolid, ID-guided

Board pearl: Duration is counted from the first negative blood culture, not the start of antibiotics. Repeat cultures every 24–48 hours until clearance; persistent positivity at day 5–7 mandates re-imaging for abscess and surgical consultation.

Streptococci (viridans, S. gallolyticus) — highly susceptible (PCN MIC ≤0.12):

Streptococci with relatively resistant PCN (MIC 0.12–0.5):

Staphylococcus aureus, native valve:

S. aureus, prosthetic valve:

Enterococcus (E. faecalis):

HACEK organisms: ceftriaxone × 4 weeks (native) or 6 weeks (prosthetic).

Fungal (Candida, Aspergillus): liposomal amphotericin B or echinocandin plus surgery; lifelong suppression with azole common.

Coxiella burnetii (Q fever): doxycycline + hydroxychloroquine × 18 months (native), 24 months (prosthetic).

Bartonella: doxycycline + gentamicin × 14 days, then doxycycline × 6 weeks.

Surgical Indications and Procedural Management

— Heart failure from valve dysfunction (acute AR/MR, fistula, prosthetic dehiscence)—#1 indication and #1 mortality driver

— Uncontrolled infection: perivalvular abscess, fistula, pseudoaneurysm, heart block, enlarging vegetation despite therapy

— Persistent bacteremia or fever >5–7 days on appropriate antibiotics with no other source

— Fungal or highly resistant organisms (MDR, VRE, Brucella)

— Prosthetic valve IE with valve dysfunction, dehiscence, or S. aureus

— Recurrent emboli despite appropriate antibiotics

— Large vegetation (>10 mm) with severe valve regurgitation

— Isolated very large vegetation (>15 mm), especially mitral

— Vegetation >10 mm + prior embolic event

— Ischemic stroke, no hemorrhage, no coma: surgery can proceed early (within days) when otherwise indicated

— Hemorrhagic stroke or large infarct: delay surgery ≥4 weeks when possible

— Always obtain head imaging before bypass anticoagulation

— Complete hardware removal (generator + all leads) is mandatory for definite CIED IE or pocket infection with bacteremia

— Percutaneous lead extraction preferred; surgical if vegetation >2 cm or extraction failure

— Reimplant only after blood cultures negative ≥72 hours (longer if vegetations); reassess need for device

— Operative mortality 6–25% depending on indication and stability

— Repair preferred over replacement for mitral valve when feasible

— Mechanical vs bioprosthetic: shared decision—age, anticoagulation tolerance, pregnancy plans

— Aortic root replacement (Bentall) if extensive root destruction

— Drain peripheral abscesses (splenic, vertebral)

— Coil/clip large or symptomatic mycotic aneurysms before cardiac surgery

— Dental extraction of severely diseased teeth pre-op when stable

CCS pearl: A patient with IE and a new 2 cm vegetation plus heart failure symptoms needs cardiothoracic surgery consult on day 1, not after completing antibiotics—early surgery improves survival in high-risk IE.

Class I indications for valve surgery (do not delay):

Class IIa — prevent embolism:

Timing of surgery in IE-associated stroke:

Cardiac implantable electronic device (CIED) infection:

Surgical mortality and considerations:

Adjunctive procedures:

Special Populations — Elderly and Renal/Hepatic Impairment

— Increasing share of IE cases—degenerative valve disease, healthcare exposures, prosthetic valves

— Atypical presentation: low-grade fever, confusion, fatigue, failure to thrive—think IE in elderly FUO

— Higher rates of S. gallolyticus and enterococcal IE (GI/GU sources)

— Surgical risk higher but advanced age alone is not a contraindication—frailty, comorbidities, and goals of care drive decision

— Heightened risk of antibiotic toxicities (renal, ototoxicity, C. difficile)

— Adjust vancomycin (target AUC/MIC 400–600, monitor trough 15–20)

— Avoid prolonged aminoglycoside courses; use ampicillin + ceftriaxone instead of amp + gent for E. faecalis IE

— Daptomycin alternative for MRSA in CKD (renal-dose adjusted; monitor CK weekly)

— Beta-lactams: nafcillin preferred over oxacillin in hepatic disease; cefazolin acceptable in MSSA with adjustment in severe CKD

— Hemodialysis patients are high IE risk (vascular access bacteremia); aggressive line/fistula management; treat S. aureus bacteremia ≥4–6 weeks and screen for IE

— Nafcillin/oxacillin primarily hepatically metabolized—monitor LFTs, consider dose adjustment in severe dysfunction

— Rifampin contraindicated in significant hepatic disease (hepatotoxic, induces many CYP enzymes—major DDI with warfarin, DOACs, antiretrovirals)

— Ceftriaxone causes biliary sludging; use cefotaxime if biliary disease

— Vancomycin + aminoglycoside or piperacillin-tazobactam → AKI risk

— Rifampin lowers warfarin, DOAC, OCP, statin, and ART levels

— Linezolid + SSRI → serotonin syndrome; thrombocytopenia with prolonged use

— Daily renal function, weekly CBC, LFTs

— Hearing/vestibular checks with prolonged aminoglycosides

— Frailty/delirium assessment, fall precautions, early PT/OT

Step 3 management: In an elderly patient with E. faecalis IE and CrCl 35, choose ampicillin + ceftriaxone × 6 weeks over ampicillin + gentamicin—equivalent efficacy with markedly less nephrotoxicity and ototoxicity. This is a recurrent Step 3 stem.

Elderly patients (>65):

Renal impairment:

Hepatic impairment:

Drug interactions to flag:

Monitoring in elderly/renal:

Special Populations — Pregnancy, Pediatrics, IDU, CIED

— Rare but high mortality (maternal 11%, fetal 33%)

— Risk factors: IDU, congenital heart disease, prior IE, prosthetic valve

— Safe antibiotics: penicillins, cephalosporins, vancomycin (category B/C historically)

— Avoid: aminoglycosides (ototoxicity), tetracyclines (teeth/bone), fluoroquinolones, rifampin (relative)

— Imaging: TTE/TEE safe; minimize CT/fluoroscopy; MRI without gadolinium preferred

— Surgery during pregnancy: bypass increases fetal loss (15–30%); ideally defer to 2nd trimester or post-delivery, but maternal indications take precedence

— Delivery planning: multidisciplinary, often vaginal with assisted second stage; C-section for obstetric indications

— Most cases occur in congenital heart disease (especially unrepaired cyanotic, VSD, bicuspid aortic valve)

— Neonatal IE associated with central lines, prematurity, S. aureus, Candida

— Empiric: vancomycin + gentamicin ± cefotaxime

— Modified Duke criteria apply; TTE often diagnostic given better windows

— Prophylaxis indicated for high-risk pediatric cardiac conditions before dental procedures

— Predominantly right-sided, tricuspid, S. aureus (often MRSA)

— Higher rates of polymicrobial, fungal, Pseudomonas, HACEK, gram-negative IE

— Addiction medicine consultation, MAT (buprenorphine/methadone), harm reduction, hepatitis C and HIV testing are integral

— OPAT (outpatient parenteral antibiotic therapy) increasingly used with structured support; oral step-down (POET trial regimens) is selective and ID-guided

— Recurrence high; second surgery has worse outcomes—shared decision-making essential

— Complete device extraction nearly always required

— Defer reimplantation until cultures sterile ≥72 h (≥2 weeks if vegetation persists)

— Reassess true device need; up to 30% may not need replacement

Board pearl: In a pregnant patient with native valve viridans strep IE, use ceftriaxone monotherapy × 4 weeks—avoids aminoglycoside ototoxicity to the fetus while providing once-daily dosing for OPAT.

Pregnancy:

Pediatrics:

Injection drug users:

CIED-related IE:

Complications and Adverse Outcomes

— Heart failure from acute valvular regurgitation (AR > MR > TR)—leading indication for surgery and #1 mortality driver

— Perivalvular abscess → fistula, pseudoaneurysm, conduction block (PR prolongation → complete heart block)

— Valve perforation, leaflet rupture, chordal rupture

— Pericarditis or purulent pericardial effusion with possible tamponade

— Myocardial infarction from coronary artery embolization (typically left main or LAD ostium from aortic valve vegetation)

— Incidence 20–50%; risk highest in first 2 weeks of therapy and falls sharply after

— CNS: ischemic stroke, hemorrhagic transformation, mycotic aneurysm, brain abscess, meningitis

— Splenic infarct/abscess, renal infarct, mesenteric ischemia, acute limb ischemia, coronary embolus

— Septic pulmonary emboli in right-sided IE: cavitary lung lesions, abscesses

— Immune complex glomerulonephritis (hematuria, RBC casts, low complement)

— Reactive arthritis, vasculitis, positive RF

— Vertebral osteomyelitis/discitis (especially with S. aureus, enterococci)

— Psoas, splenic, hepatic abscesses

— Septic arthritis, endophthalmitis (especially Candida, S. aureus)

— Intracranial > visceral; risk of catastrophic rupture

— Screen with CTA/MRA if focal neuro signs, severe headache, or before cardiac surgery requiring bypass anticoagulation

— Endovascular coiling or surgical clipping if large, expanding, or symptomatic

— Vancomycin AKI, red man syndrome, DRESS

— Aminoglycoside nephrotoxicity and ototoxicity

— Daptomycin myopathy (check CK weekly)

— Line-associated complications: DVT, secondary bacteremia, C. difficile colitis

— In-hospital 15–25%; 1-year 30%; higher in S. aureus, prosthetic valve, healthcare-associated, and surgical candidates not operated on

Key distinction: Anticoagulation is not initiated for vegetations themselves (no proven benefit, increases hemorrhagic conversion risk). Continue existing anticoagulation only for a clear independent indication (e.g., mechanical valve), and hold temporarily after CNS embolic event until imaging clarifies hemorrhage risk.

Cardiac complications (most common cause of death):

Embolic complications:

Immunologic complications:

Metastatic infection:

Mycotic aneurysms:

Treatment-related complications:

Mortality:

When to Escalate Care — ICU, Consult, Inpatient Triage

— Septic shock or hemodynamic instability requiring vasopressors

— Acute pulmonary edema from valvular failure

— New high-grade AV block or sustained arrhythmia

— Large embolic stroke with airway/neurologic compromise

— Status post embolic MI

— Respiratory failure (septic pulmonary emboli with ARDS)

— Infectious disease: antibiotic stewardship, source identification, OPAT planning

— Cardiology: imaging interpretation, hemodynamics, anticoagulation balance

— Cardiothoracic surgery: early surgical assessment for any high-risk feature—do not wait until antibiotics fail

— Neurology/Neurosurgery: stroke, mycotic aneurysm management

— Addiction medicine: IDU patients (MAT initiation in hospital improves engagement)

— Dental: source eradication before valve surgery when stable

— Multidisciplinary team improves mortality 30–40% in observational studies

— All prosthetic valve IE

— Any surgical indication

— Culture-negative or unusual organism

— CIED-related IE

— Need for valve surgery not available locally

— Mechanical circulatory support need (ECMO, IABP)

— Complex CIED/lead extraction

— Mycotic aneurysm requiring endovascular therapy

— Afebrile ≥48 hours

— Hemodynamically stable, no heart failure

— Negative surveillance blood cultures

— OPAT plan: PICC placed, antibiotic schedule confirmed, weekly labs arranged (CBC, BMP, drug levels, LFTs)

— ID and cardiology outpatient follow-up booked

— Addiction services engaged if IDU

CCS pearl: In CCS cases, the high-value early-clock actions are: draw 3 blood culture sets → start empiric IV antibiotics → order TTE → consult ID, cardiology, and CT surgery → admit to telemetry (or ICU if unstable) → daily blood cultures until negative. Missing the early CT surgery consult in a complicated case is a frequent CCS deduction.

All suspected IE patients are admitted—outpatient management of new IE is not appropriate.

ICU admission criteria:

Consultations within 24 hours:

Indications for "Endocarditis Team" activation:

Transfer to tertiary center:

Discharge readiness checklist:

Key Differentials — Same-Category (Endovascular/Cardiac Infection)

— Sterile fibrin-platelet vegetations

— Seen in advanced malignancy (mucinous adenocarcinomas: pancreas, lung, GI), DIC, chronic inflammatory states, antiphospholipid syndrome

— Presents with systemic emboli (stroke in cancer patient is classic) without fever or positive cultures

— Diagnosis: TEE shows vegetations; blood cultures negative; evaluate for underlying malignancy

— Treatment: anticoagulation (LMWH preferred) + treat underlying disease—do not give antibiotics

— Sterile verrucous vegetations on either side of mitral valve in SLE/APLS

— Often asymptomatic; embolic risk

— Treat underlying lupus and anticoagulate per APLS guidelines

— Post-streptococcal pharyngitis (2–4 weeks)

— Jones criteria: carditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules

— Aschoff bodies histologically; MacCallum plaques in atria

— Treatment: penicillin + anti-inflammatories; long-term IM penicillin prophylaxis

— Bacteremia from line that resolves rapidly with line removal and short antibiotic course

— S. aureus bacteremia always warrants echo to rule out IE; CoNS often contaminant unless persistent or prosthetic material present

— Local erythema, drainage, no bacteremia, sterile lead vegetations on TEE

— Still typically requires full device removal

— Cardiac tumors that mimic vegetations on echo

— Myxoma: most often left atrial, "ball-valve" obstruction, constitutional symptoms, elevated IL-6

— Papillary fibroelastoma: aortic valve, embolic risk; resect when symptomatic

— Mechanical valves; presents with heart failure, stroke; TEE/fluoroscopy distinguishes

— Treatment: anticoagulation, fibrinolysis, or surgery—not antibiotics

Key distinction: Fever + vegetation + negative cultures + cancer history → think marantic endocarditis, not culture-negative IE. Anticoagulate, image for malignancy, withhold prolonged antibiotics.

Non-bacterial thrombotic endocarditis (NBTE / marantic endocarditis):

Libman-Sacks endocarditis:

Rheumatic fever / rheumatic carditis:

Catheter-associated bloodstream infection without IE:

Pacemaker pocket infection without lead/valve involvement:

Myxoma and papillary fibroelastoma:

Prosthetic valve thrombosis or pannus:

Key Differentials — Other-Category Mimics

— UTI urosepsis, pneumonia with bacteremia, intra-abdominal source

— TTE/TEE negative; bacteremia clears promptly with source control

— ANCA-associated vasculitis (GPA, MPA): fever, hematuria/RBC casts, pulmonary nodules with cavitation—mimics right-sided IE

— Distinguishing features: positive ANCA, negative cultures, sinus/upper-airway involvement, biopsy

— Cryoglobulinemic vasculitis: HCV-related, palpable purpura, low complement

— Fever, arthritis, hematuria, anemia, immune phenomena overlap

— Positive ANA, anti-dsDNA, low complement; Libman-Sacks if vegetations present

— Constitutional symptoms (fevers, weight loss), embolic events, "tumor plop" murmur

— Echo diagnostic; cultures negative; resect

— Pentad: MAHA, thrombocytopenia, fever, renal dysfunction, neurologic signs

— ADAMTS13 activity <10%; schistocytes on smear

— Treat with plasma exchange—not with antibiotics

— Chronic fevers, weight loss, pulmonary findings; consider in immunocompromised, foreign-born

— Specific cultures, IGRA, fungal serologies

— B symptoms, anemia, splenomegaly, hematuria mimic subacute IE

— Imaging, peripheral smear, biopsy, tumor markers

— Especially in IDU, HIV, or polypharmacy patients—diagnosis of exclusion after IE ruled out

— Doppler/ultrasound for line thrombus; manage with line removal and anticoagulation per indication

Board pearl: A young patient with fever, hematuria, RBC casts, and pulmonary nodules has two competing diagnoses: right-sided IE and ANCA vasculitis (GPA). Order blood cultures, TTE, ANCA, and consider sinus/upper-airway exam—treating the wrong one is catastrophic. Always send cultures before starting steroids.

Sepsis / bacteremia without endocarditis:

Vasculitis:

Systemic lupus erythematosus:

Atrial myxoma:

Thrombotic thrombocytopenic purpura (TTP):

Disseminated tuberculosis or fungal infection:

Malignancy (lymphoma, leukemia, renal cell carcinoma):

Drug fever / serum sickness:

Catheter-related thrombosis with bacteremia (mimics line-related IE):

Secondary Prevention, Discharge Meds, and Long-Term Plan

— Total IV duration typically 4–6 weeks from first negative blood culture

— OPAT via PICC most common; daily/BID dosing favored

— Selective oral step-down (POET trial) acceptable in stable left-sided IE after ≥10 days of IV therapy, ID-directed

— Indicated only for highest-risk patients AND specified procedures

— High-risk patients: prosthetic valve or prosthetic material used for valve repair, prior IE, unrepaired cyanotic CHD or repaired CHD with residual defect or within 6 months of repair, cardiac transplant recipients with valvulopathy

— Procedures requiring prophylaxis: dental procedures involving gingival/periapical tissue or oral mucosa perforation; respiratory procedures with mucosal incision; infected skin/MSK procedures

— GI/GU procedures no longer routinely covered unless active infection

— Standard regimen: amoxicillin 2 g PO 30–60 min before procedure; clindamycin no longer first-line for PCN allergy—use cephalexin, azithromycin, or doxycycline

— Establish dental home; routine cleanings, twice-daily brushing, flossing

— Treat caries/periodontal disease promptly—poor dentition is a major recurrence risk

— IDU: MAT (buprenorphine/methadone), behavioral therapy, naloxone prescription, syringe service program referral, HIV/HCV linkage

— Hemodialysis: minimize tunneled catheters, transition to AVF when possible

— CIED: only reimplant if clearly indicated; minimize unnecessary lines/ports

— Baseline post-treatment TTE to document residual valve function/structure

— Anticoagulation per mechanical valve protocol (warfarin, target INR by valve type/position)

— Heart failure GDMT if reduced EF post-IE

— Annual influenza, pneumococcal (PCV20 or PCV15+PPSV23), COVID-19 boosters, hepatitis B (especially IDU/HD)

Step 3 management: Patient with bioprosthetic mitral valve needs amoxicillin 2 g prophylaxis before dental extraction; same patient does not need prophylaxis for routine colonoscopy. Wrong-indication prophylaxis is a common stem trap.

Antibiotic completion:

Endocarditis prophylaxis for future procedures (AHA 2007/2021):

Dental and oral health:

Address modifiable risk factors:

Cardiac follow-up:

Vaccinations:

Follow-Up, Monitoring, and Counseling

— Daily exam: heart sounds, JVP, lungs, neuro check, IV site

— Surveillance blood cultures every 24–48 hours until clearance documented

— Daily CBC, BMP; vancomycin levels (trough or AUC) every 3–5 days

— Weekly LFTs (nafcillin, rifampin), CK (daptomycin), hearing assessment (aminoglycosides)

— Repeat TTE/TEE if new murmur, persistent fever, worsening clinical status, or before completing therapy to establish baseline

— PICC line care, weekly nurse visits, labs faxed to ID

— Weekly ID review of cultures, drug levels, renal function

— 24/7 contact line for fever, line issues, AKI

— ID clinic 1–2 weeks after discharge, then end of therapy

— Cardiology 2–4 weeks; TTE at end of treatment and at 3, 6, 12 months

— PCP within 1 week to reconcile medications, screen for C. difficile, address comorbid conditions

— Dental within 4–6 weeks for source control and maintenance plan

— Addiction medicine weekly to monthly if IDU; MAT continuation critical

— Recognize recurrence: fever, night sweats, new fatigue, embolic symptoms—seek care, draw cultures before antibiotics

— Inform all future providers of IE history (wallet card)

— Avoid unnecessary IV lines, tattoos, piercings; meticulous skin care

— Oral hygiene as endocarditis prevention

— Prophylaxis indications and limits

— Cardiac rehab post-valve surgery

— PT/OT for embolic stroke recovery

— Nutrition for catabolic recovery; address weight loss/sarcopenia

— Mental health: depression and PTSD common after prolonged hospitalization

Board pearl: Recurrence rate is ~5–10% lifetime; risk is highest in IDU, prosthetic valve, and inadequately treated initial infection. Any new fever in an IE survivor warrants 3 blood cultures before any antibiotics—premature empiric therapy can sabotage diagnosis for weeks.

Inpatient monitoring during therapy:

OPAT structure:

Post-discharge follow-up cadence:

Patient counseling:

Rehab and functional recovery:

Ethical, Legal, and Patient Safety Considerations

— High-yield Step 3 ethics scenario: patient with recurrent IE after first valve replacement, ongoing IDU, requesting second surgery

— Active IDU is not an absolute contraindication to repeat surgery

— Decision involves multidisciplinary team (CT surgery, ID, addiction medicine, ethics, social work) and patient autonomy

— Bias against patients with substance use disorders is documented; address with structured criteria, MAT initiation, harm reduction

— Document shared decision-making, surgical risks, expected outcomes, role of MAT and addiction treatment

— Embolic stroke patient with aphasia or impaired cognition—use surrogate decision-maker (spouse, healthcare proxy, next of kin per state hierarchy)

— Document capacity assessment; involve ethics if family disagreement

— Emergent surgery in unconscious unstable patient: implied consent doctrine applies

— OPAT failure modes: missed doses, line infection, ED revisits—mitigate with structured OPAT program, weekly labs, 24/7 hotline

— Medication reconciliation at discharge: rifampin interactions (warfarin, DOACs, OCP, statins, ART) must be communicated to all prescribers

— Ensure end-of-therapy TTE is scheduled before discharge

— Hand-off to PCP with explicit recurrence-recognition counseling

— Public health reporting varies by state; some require reporting of S. aureus bacteremia, MRSA, C. difficile

— Healthcare-associated IE (e.g., dialysis-catheter source) triggers infection control review and possible root-cause analysis

— Avoid unnecessary central lines; consider midlines for shorter courses

— Hand hygiene, chlorhexidine bathing in inpatient setting

— Prevent secondary C. difficile with antibiotic stewardship

— Document blood culture timing and antibiotic start to demonstrate adherence to sepsis bundles

— OPAT access may be limited by insurance or housing—uninsured/unhoused patients may need full inpatient course; do not discharge to inappropriate setting

Step 3 management: When an IDU patient requests a third valve surgery, do not unilaterally refuse based on substance use—convene the endocarditis and ethics teams, optimize MAT, set explicit care plan, and document the shared decision. Refusing care based solely on addiction is an ethics violation.

Repeat valve surgery in active IDU:

Informed consent edge cases:

Transition-of-care risks (very Step 3):

Mandatory and recommended reporting:

Patient safety / quality measures:

Resource and equity considerations:

High-Yield Associations and Rapid-Fire Facts

— S. aureus → IDU, healthcare-associated, prosthetic valve (early), most common overall

— Viridans streptococci → poor dentition, subacute, native valve

— S. gallolyticus (bovis) → colon cancer—order colonoscopy

— Enterococcus → elderly, GU/GI source, post-instrumentation

— Coagulase-negative staph (CoNS) → prosthetic valves, especially early post-op

— HACEK → culture-negative historically; now usually culture-positive in modern systems; native valve

— Coxiella burnetii → farm/livestock, raw milk → Q fever endocarditis

— Bartonella → homeless, cat scratch, alcohol use disorder

— Candida → IDU with brown heroin, TPN, prosthetic valves; large vegetations; mandatory surgery

— Pseudomonas → IDU (especially with adulterants)

— Right-sided (tricuspid) → IDU, septic pulmonary emboli

— Left-sided (mitral > aortic) → systemic emboli, heart failure

— Aortic root abscess → new AV block

— Do not start anticoagulation for IE vegetations

— Continue existing AC for mechanical valves unless intracranial hemorrhage

— Hold AC for 1–2 weeks after embolic stroke pending imaging

— Prosthetic valve + dental gum manipulation = yes (amoxicillin 2 g)

— Mitral valve prolapse without prior IE = no

— Bicuspid aortic valve without prior IE = no

— Routine GI/GU procedures = no (unless active infection)

— Heart failure, Hardware (prosthetic) involvement, Highly resistant/fungal

— Extension perivalvular (abscess), Embolic risk (large vegetation), Enduring bacteremia (persistent fever/cultures)

Board pearl: Two reflex orders to memorize—S. aureus bacteremia → echo; S. gallolyticus bacteremia → colonoscopy. These appear nearly every exam cycle.

Pathogen → tip-off pairings:

Vegetation location/side clues:

Anticoagulation rules:

Prophylaxis quick check:

Surgery indication memory aid (the 3 H's + 3 E's):

Mortality drivers: heart failure > stroke > sepsis > uncontrolled infection

Modified Duke criteria still cornerstone; 2023 Duke-ISCVID update added PET/CT as major criterion for prosthetic valve IE

Board Question Stem Patterns

— Diagnosis: right-sided IE (tricuspid), S. aureus with septic pulmonary emboli

— Next: blood cultures × 3 → empiric vancomycin → TTE (then TEE if needed)

— Diagnosis: subacute IE; if S. gallolyticus, mandate colonoscopy

— Echo (TEE if TTE negative); duration 4–6 weeks; consider AV graft as source; remove tunneled catheter

— Diagnosis: prosthetic valve IE with aortic root abscess

— Next: TEE, broad empiric coverage (vanc + gent + cefepime + rifampin), urgent CT surgery consult

— Diagnosis: Libman-Sacks endocarditis; treat lupus, anticoagulate; do not prolong antibiotics

— Diagnosis: marantic (NBTE) endocarditis; treat with LMWH, address malignancy

— Action: repeat TEE, look for perivalvular abscess, escalate to surgery

— Action: amoxicillin 2 g PO 30–60 min before procedure

— Treat with ceftriaxone; avoid aminoglycosides and tetracyclines

— Delay surgery ≥4 weeks if feasible; manage AC carefully

— No prophylaxis indicated

Key distinction: When stems present fever + new murmur + embolic phenomena, the answer cascade is almost always: blood cultures × 3 → empiric IV antibiotics → TTE → TEE if needed → ID + CT surgery consult. Memorize this sequence cold.

Stem 1: "IDU presents with fever, pleuritic chest pain, hemoptysis. Multiple nodules on CXR."

Stem 2: "Elderly man with viridans strep bacteremia, fatigue, weight loss, anemia."

Stem 3: "Patient on hemodialysis with new murmur, S. aureus bacteremia."

Stem 4: "Post-aortic-valve-replacement 2 months, fever, new diastolic murmur, PR interval prolonged."

Stem 5: "Young woman with SLE, stroke, vegetations on mitral valve, three negative blood cultures."

Stem 6: "Pancreatic cancer patient, embolic stroke, mitral vegetation, cultures negative."

Stem 7: "IE patient at 7 days of vancomycin still bacteremic and febrile."

Stem 8: "Patient with prior IE due to viridans strep, scheduled for dental cleaning with scaling."

Stem 9: "Pregnant patient with viridans strep IE."

Stem 10: "IE with embolic stroke; surgery planned. Imaging shows hemorrhagic conversion."

Stem 11: "Patient with bicuspid aortic valve, no prior IE, asks about prophylaxis for colonoscopy."

One-Line Recap

— Viridans strep → PCN or ceftriaxone × 4 wk

— MSSA → nafcillin × 6 wk; MRSA → vancomycin × 6 wk

— Enterococcus → ampicillin + ceftriaxone × 6 wk (less nephrotoxic than amp+gent)

— Prosthetic valve staph → add rifampin + 2 wk gentamicin

— Count duration from first negative blood culture

Board pearl: If you remember nothing else: cultures first, echo early, surgery sooner than you think, duration from first negative culture, and prevent the next episode through dental health, MAT, and judicious prophylaxis.

One-line teaching point: Infective endocarditis is diagnosed by combining persistent bacteremia with echocardiographic evidence (modified Duke criteria), treated with prolonged pathogen-directed IV antibiotics from the first negative culture, and managed surgically when there is heart failure, uncontrolled infection (abscess/fistula/persistent bacteremia), large or embolizing vegetations, or prosthetic/fungal/highly resistant infection—best delivered by a multidisciplinary endocarditis team.

Diagnosis pearl: Three blood culture sets from separate sites before antibiotics; TTE first, TEE if prosthetic valve, persistent bacteremia, suspected abscess, or non-diagnostic TTE.

Antibiotic pearl:

Surgery pearl: Operate early for heart failure from valve dysfunction, perivalvular abscess/heart block, persistent bacteremia, fungal or MDR organism, prosthetic valve dysfunction, or large vegetation with embolic event—do not wait for antibiotics to fail.

Reflex orders pearl: S. aureus bacteremia → echo; S. gallolyticus bacteremia → colonoscopy; new AV block in IE → TEE for aortic root abscess + urgent surgical consult; IE in IDU → addiction medicine, MAT, HIV/HCV testing; prior IE or prosthetic valve before dental gingival manipulation → amoxicillin 2 g.