Basics
Description
Infective endocarditis (IE) is a microbial infection of the endocardium of the heart.
Epidemiology
Incidence
- IE is relatively uncommon. The estimated incidence is 0.3 per 100,000 children per year.
- The overall incidence of endocarditis decreased with the advent of antibiotics. However, a recent increase in frequency has been associated with improved survival of patients with congenital heart disease and the more widespread and often prolonged use of central vascular catheters, especially in premature infants.
Risk Factors
- Preexisting heart disease (congenital or acquired)
- Prior history of endocarditis
- Cardiac surgery
- Intracardiac pacemakers and implantable cardioverter-defibrillators
- Prosthetic valves or conduits
- Indwelling catheters/IV drug use
General Prevention
- Dental hygiene
- Minimal use of central lines
- Correction of the cardiovascular anomaly by surgery or interventional catheterization techniques
- Subacute bacterial endocarditis (SBE) prophylaxis regimes as per the 2007 American Heart Association (AHA) recommendations. Give as a single dose 30-60 minutes prior to procedure:
- Oral: amoxicillin (50 mg/kg, max 2.0 g)
- IV or IM: ampicillin (50 mg/kg, max 2.0 g) or ceftriaxone/cefazolin (50 mg/kg, max 1.0 g)
- Oral for penicillin-allergic patients: cephalexin, if no history of urticaria, angioedema, or anaphylaxis (50 mg/kg, max 2.0 g); clindamycin (20 mg/kg PO/IV, max 600 mg); or azithromycin/clarithromycin (15 mg/kg PO, max 500 mg)
- IV or IM for penicillin-allergic patients: cefazolin, ceftriaxone, or clindamycin (doses as above)
- SBE prophylaxis is recommended by the AHA only for the following cardiac conditions:
- Prosthetic cardiac valve or prosthetic material used for cardiac valve repair
- Prior history of IE
- Unrepaired cyanotic congenital heart disease, including palliative shunts and conduits
- Congenital heart defect repaired with prosthetic material or device for the first 6 months after the procedure
- Repaired congenital heart disease with residual defect near the site of prosthetic patch or device
- Cardiac transplantation recipients with cardiac valvulopathy
- SBE prophylaxis is recommended only for the following procedures:
- Dental procedures involving manipulation of the gingival or periapical region of teeth or perforation of the oral mucosa
- Invasive respiratory tract procedures involving incision or biopsy, such as tonsillectomy/adenoidectomy or abscess drainage
- Surgery involving prosthetic intravascular or intracardiac material, including heart valves
- Procedures that do not require SBE prophylaxis:
- Placement of removable prosthodontic or orthodontic appliances
- Bleeding from trauma to the lips or oral mucosa or shedding of deciduous teeth
- Routine anesthetic injections through noninfected oral mucosa tissues
- Bronchoscopy without a biopsy
- Gastrointestinal (GI) or genitourinary procedures: Prophylaxis solely to prevent IE is not recommended.
Pathophysiology
- IE is primarily seen in patients with preexisting heart disease (congenital or acquired) who develop bacteremia with organisms that are likely to cause infection.
- IV drug abusers and patients with indwelling central venous catheters may develop endocarditis even in the absence of prior heart disease.
- Local turbulence secondary to the cardiovascular abnormality is thought to result in damage of the endocardial surface. The development of a fibrin and platelet network occurs in which bacteria may then become entrapped, causing infection.
- Bacteremia may be a complication of focal infection (e.g., pneumonia, cellulitis, or urinary tract infection) or may be associated with various dental and surgical procedures. Bacteremia, however, also occurs spontaneously with usual activities, such as chewing, flossing, and brushing teeth.
- Peripheral manifestations in chronic endocarditis are mediated by immune complex reactions.
Etiology
- Gram-positive cocci account for 90% of culture-positive endocarditis. There has been a recent shift in the microbial etiology, corresponding with a more acute presentation:
- Streptococcus viridans and Staphylococcus aureus are the most common agents.
- Other organisms that can cause endocarditis are coagulase-negative staphylococci, β-hemolytic streptococci, enterococci, the HACEK group (Haemophilus aphrophilus, Haemophilus paraphrophilus, Haemophilus parainfluenzae, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella species), Candida species, Aspergillus species, Pseudomonas species, pneumococci, and Neisseria species.
- <20% of endocarditis cases are reported as culture negative.
Diagnosis
- The Modified Duke criteria define diagnostic categories (definite endocarditis, possible endocarditis, and rejected cases) based on combinations of major and minor criteria.
- Criteria:
- Major: organism specific for IE demonstrated by positive blood culture or histologic specimen and definitive echocardiographic data
- Minor: predisposing heart disease, fever, vascular/immunologic phenomena, or microbiologic evidence not within major criteria
- Definitive endocarditis requires 2 major, or 1 major plus 3 minor, or 5 minor criteria.
- Several studies have confirmed the high sensitivity and specificity of these criteria.
History
- Fever
- Malaise
- Anorexia
- Weight loss
- Heart failure symptoms
- Arthralgia/myalgia
- Neurologic symptoms
- GI symptoms
- Chest pain
- Occasionally, a recent infection, dental visit, or surgical procedure can be identified.
- Acute endocarditis is associated with a more rapidly progressive, fulminant course.
Physical Exam
- General
- Fever (usually low grade with α-hemolytic streptococci and high grade with S. aureus)
- Petechiae (occurring in 1/3 of cases)
- Embolic or immunologic phenomena
- Renal: glomerulonephritis, infarct
- Splinter hemorrhages
- Retinal hemorrhages (Roth spots)
- Osler nodes (painful)
- Janeway lesions (painless)
- Splenomegaly (occurring in about 50% of cases)
- Arthralgia/arthritis
- Neurologic: cerebral infarction, embolism, or hemorrhage. Mycotic aneurysms may also occur.
- Cardiac/valvulitis
- New or change in heart murmur
- Signs of congestive heart failure (CHF)
- Newborns with IE may present with feeding difficulty, respiratory distress, tachycardia, hypotension, seizures, apnea, and septic emboli.
Diagnostic Tests & Interpretation
Lab
- Blood cultures
- Most important diagnostic test for endocarditis
- Positive in 85-90% of reported cases
- Obtain 3-5 sets from different sites during the first 24 hours of suspected endocarditis.
- Collect the largest volume that is clinically reasonable.
- The bacteremia of endocarditis is continuous; therefore, it is not necessary to wait to obtain the blood cultures during a fever spike.
- Nonspecific data
- Elevated erythrocyte sedimentation rate (ESR) (80%) and C-reactive protein
- Anemia (44%)
- Positive rheumatoid factor (38%)
- Hematuria (35%) and red cell casts
- Leukocytosis
- Decreased complement
Imaging
- Echocardiography, transthoracic
- Valuable noninvasive technique in the identification of vegetations
- Specificity is 98%, but sensitivity is <60%, so a negative echocardiogram does not rule out endocarditis.
- Also invaluable for follow-up, including evaluation for potential cardiac complications
- Echocardiography, transesophageal
- Especially in older or obese patients, provides better visualization of smaller vegetations, with sensitivity of 76-100%
- Recommended in patients with an inconclusive transthoracic study but a high index of suspicion for endocarditis
Alert
- The absence of vegetation(s) by echocardiography does not rule out endocarditis.
- In patients with a prosthetic valve, echocardiography is not always helpful as there is frequently artifact from the prosthetic valve. Abnormal movements of the valve leaflets may suggest a vegetation.
- The ESR may remain elevated for some time, even after cessation of bacteremia.
Diagnostic Procedures/Other
Electrocardiogram: New-onset abnormalities such as atrioventricular block (even 1st-degree) may represent conduction system and myocardial involvement from invasive disease.
Differential Diagnosis
- Other infections
- Acute rheumatic fever
- Malignancy
- Connective tissue disorders
Treatment
Medication
Antibiotics
- Prolonged IV therapy (at least 4 weeks) is needed.
- Choice of antibiotic(s) and duration of treatment depend on the infecting organism, sensitivity pattern, and patient risk factors.
- For staphylococcal or fungal endocarditis, IV therapy is given for at least 6-8 weeks.
Surgery/Other Procedures
- Severe/worsening CHF
- Valvular disease with unstable hemodynamics
- Failing medical therapy
- Large (>10 mm), mobile vegetations
- ≥2 major embolic events
- Fungal endocarditis
- Abscess formation/periannular extension
- Prosthetic valve endocarditis
Inpatient Considerations
Initial Stabilization
- Rest
- Antipyretics
- Optimal nutrition and hydration
- Careful dental hygiene
Ongoing Care
Follow-up Recommendations
Patient Monitoring
- Obtain repeat blood cultures after a few days of antibiotic or antifungal therapy to ensure the eradication of bacteria.
- Obtain blood cultures again 2 months after completion of a full course of antibiotic therapy.
Prognosis
If diagnosed in a timely fashion and appropriate therapy is instituted, prognosis is relatively good for bacterial endocarditis. S. aureus and fungal endocarditis are associated with higher morbidity and mortality.
Complications
Despite improvements in diagnosis and treatment, IE continues to be a disease with significant morbidity and mortality (~10-20%):
- Cardiac: valve destruction and perforation leading to incompetence, abscess and fistula formation, heart failure, or conduction abnormalities
- Embolic events (22-50%) may occur to multiple organ systems (central nervous system, bowel, coronary arteries, kidneys, spleen, skin, lungs).
Additional Reading
- Ferrieri P, Gewitz MH, Gerber MA, et al. Unique features of infective endocarditis in childhood. Circulation. 2002;105(17):2115-2126. [View Abstract]
- Knirsch W, Nadal D. Infective endocarditis in congenital heart disease. Eur J Pediatr. 2011;170(9):1111-1127. [View Abstract]
- McDonald JR. Acute infective endocarditis. Infect Dis Clin North Am. 2009;23(3):643-664. [View Abstract]
- Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis: guidelines from the American Heart Association. Circulation. 2007;116(15):1736-1754. [View Abstract]
Codes
ICD09
- 424.9 Endocarditis, valve unspecified, unspecified cause
- 421 Acute and subacute bacterial endocarditis
- V07.39 Need for other prophylactic chemotherapy
ICD10
- I38 Endocarditis, valve unspecified
- I33.0 Acute and subacute infective endocarditis
SNOMED
- 56819008 Endocarditis (disorder)
- 73774007 Subacute bacterial endocarditis (disorder)
- 426931009 Subacute bacterial endocarditis prophylaxis (procedure)
FAQ
- Q: I forgot to give my child antibiotics prior to the procedure. Should I give him a dose afterward?
- A: The dosage may be administered up to 2 hours after the procedure.
- Q: SBE prophylaxis is recommended for my child, but she already is on long-term antibiotic therapy with that recommended antibiotic. Should she use an additional antibiotic or increase her current dose for the procedure?
- A: An antibiotic from a different class should be selected.
- Q: My child has a congenital heart defect. Does he/she require SBE prophylaxis?
- A: The answer depends on the type of the congenital heart defect and the status of any needed intervention. The child's physician should be contacted regarding the need for prophylaxis.