Infective Endocarditis: Nursing Study Guide

Infective endocarditis is a life-threatening infection of the heart valves with high NCLEX yield. This guide covers its causes, hallmark physical findings, diagnostic Duke criteria, antibiotic management, and the nursing priorities every student must know.

What Is Infective Endocarditis?

• Infection of the heart valves caused by bacteria entering the bloodstream.
• Vegetations (clumps of bacteria and fibrin) form on valves, destroy tissue, and can embolize to distant organs.

Risk Factors

• Prosthetic heart valves, previous endocarditis, congenital heart disease.
• IV drug use, long-term IV catheters, dialysis, poor oral hygiene.
• Valvular disease from rheumatic fever or aging.

Causative Organisms

• Viridans streptococci — dental procedures, poor oral hygiene; most common cause of native valve endocarditis.
• Staphylococcus aureus — most common cause overall, especially in IV drug users; most virulent and rapidly destructive; acute presentation.
• Enterococcus faecalis — GI or GU procedures, elderly men; often from a urinary source.
• Coagulase-negative staphylococci — prosthetic valves, hospital-acquired; up to 3 months post-op; less virulent.
• HACEK group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella) — culture-negative endocarditis.
• Fungi (Candida) — IV drug users, immunocompromised; large vegetations; poor prognosis.

Clinical Presentation

Symptoms

• Fever, chills, night sweats, malaise, weight loss.
• Heart failure symptoms (dyspnea, orthopnea, edema) if valves are destroyed.

Physical Findings

• A new or changing heart murmur is the most common sign.
• Fever is persistent or relapsing in 80–90% of patients.
• Osler's nodes — painful red nodules on finger pads and toe pads.
• Janeway lesions — painless flat red spots on palms and soles.
• Roth spots — retinal hemorrhages with pale centers on eye exam.
• Splinter hemorrhages — linear reddish-brown lines under fingernails and toenails.
• Petechiae — small red spots on skin and mucous membranes.
• Splenomegaly — enlarged spleen from immune response.

Mnemonic — "JONES": Janeway lesions, Osler's nodes, New murmur, Emboli (systemic), Splinter hemorrhages.

Key NCLEX distinction: Osler's nodes are painful; Janeway lesions are painless.

Diagnostic Criteria (Duke Criteria) — "BE TIMER" Mnemonic

Major Criteria

• B — Blood cultures: Two separate positive cultures with typical organisms.
• E — Echocardiogram: Imaging shows vegetation, abscess, or new partial dehiscence of a prosthetic valve.

Minor Criteria

• T — Temperature: Fever above 38.0°C (100.4°F).
• I — Immune phenomena: Osler's nodes, Roth spots, glomerulonephritis.
• M — Microbiologic evidence: Positive cultures not meeting major criteria.
• E — Embolic phenomena: Arterial emboli, septic pulmonary infarcts, Janeway lesions.
• R — Risk factors: Predisposing heart condition or IV drug use.

Diagnosis Thresholds

• Definite: 2 major, OR 1 major + 3 minor, OR 5 minor.
• Possible: 1 major + 1 minor, OR 3 minor.

Diagnostic Tests

• Blood cultures from three sites before antibiotics.
• Transthoracic echocardiogram (TTE) — first-line for native valves.
• Transesophageal echocardiogram (TEE) — gold standard for prosthetic valves.
• ECG — to detect new heart block (suggests abscess).
• Chest X-ray — to detect septic emboli.

Prevention (Antibiotic Prophylaxis)

Who Needs It (High-Risk Only)

• Prosthetic valves, previous endocarditis, unrepaired congenital heart disease.
• Cardiac transplant with valve issues.

Regimen

• Amoxicillin 2 g PO 60 minutes before dental procedures.
• Penicillin-allergic: cephalexin, doxycycline, or azithromycin.
• Clindamycin is no longer recommended (severe C. diff risk).

Antibiotic Therapy

• IV bactericidal antibiotics for 4–6 weeks.
• Organism-specific based on cultures.
• Stable patients may switch to oral after 10 days.

Organism-specific regimens:

• Viridans streptococci: Penicillin or ceftriaxone for 4 weeks.
• Enterococcus: Ampicillin + gentamicin for 4–6 weeks.
• MSSA: Nafcillin or oxacillin for 6 weeks.
• MRSA: Vancomycin for 6 weeks.

Surgical Indications

• Acute valve regurgitation with heart failure.
• Uncontrolled infection despite antibiotics.
• Fungal endocarditis.
• Abscess or fistula formation.
• Large vegetation (>10 mm) with emboli.

Complications

• Heart failure — most common complication; from valve destruction.
• Systemic emboli — stroke, MI, or organ infarction.
• Perivalvular abscess — presents as new heart block on ECG; requires surgery.
• Glomerulonephritis — hematuria and kidney injury from immune complex deposition.
• Mortality: 20–25% despite optimal treatment.

Nursing Care

• Monitor vital signs and temperature frequently.
• Assess daily for new murmurs, heart failure, and emboli.
• Inspect skin for characteristic lesions.
• Administer IV antibiotics on time.
• Monitor for bleeding and antibiotic side effects.
• Encourage rest and obtain daily weights.

Patient Teaching

• Complete the full antibiotic course.
• Maintain excellent oral hygiene and attend regular dental visits.
• Inform all providers about valve condition.
• Report fever, chills, or signs of emboli (sudden weakness, chest pain).
• Know your valve type and anticoagulation needs after surgery.

Common NCLEX Traps

• Clindamycin is no longer recommended for prophylaxis.
• Prophylaxis is only for high-risk patients.
• Osler's nodes are painful; Janeway lesions are painless.
• TEE is better than TTE for prosthetic valves.
• New heart block = abscess until proven otherwise.
• IV drug users → right-sided (tricuspid) endocarditis with S. aureus.
• Bactericidal antibiotics required, not bacteriostatic.

Key Takeaways

• Infective endocarditis = valve infection with vegetations that destroy tissue and embolize; suspect with fever + new murmur.
• S. aureus is the most common cause overall (especially IV drug users); viridans streptococci is most common in native valves after dental sources.
• Diagnose with the Duke criteria using blood cultures and echocardiogram (TEE for prosthetic valves).
• Treat with 4–6 weeks of IV bactericidal antibiotics; surgery for heart failure, abscess, fungal infection, or large vegetations.
• Prophylaxis: amoxicillin 2 g PO 1 hour before dental work in high-risk patients only — not clindamycin.
• Remember the painful/painless distinction: Osler = Ouch, Janeway = painless.