Endocarditis

Diagnosis

Indications for Testing

• Risk factor and appropriate clinical presentation

Criteria for Diagnosis

• To establish final diagnosis, use the Duke Criteria for Infective Endocarditis

Laboratory Testing

• CBC – frequently leukocytosis and left shift toward immature cell forms
• Blood cultures – 3-5 sets from separate venipuncture sites; first and last set at least 1 hour apart
• ESR/CRP – frequently elevated but not diagnostic
• In blood culture-negative disease, consider
  • Coxiella antibodies
  • Bartonella
  • HACEK organisms
  • Brucella
  • Cardiobacterium hominis
  • Eikenella corrodens
  • Kingella kingae
  • Antinuclear antibodies (ANA)/rheumatoid arthritis (RA)
  • 16s rDNA by PCR
  • More unusual causes – Tropheryma whipplei, fungi (yeasts, molds)

Imaging Studies

• Transthoracic echocardiogram (TTE) or transesophageal echocardiogram (TEE) is the gold standard for visualization of vegetations, but negative study does not rule out endocarditis
  • TTE
    • Recommended first test
    • 60-65% sensitive – sensitivity dependent on vegetation size; if >10 mm, test is 100% sensitive
  • TEE
    •  Use in patients with high clinical suspicion and negative TTE
    • 85-95% sensitive; negative study has negative predictive value of 90%

Differential Diagnosis

• Infectious
  • Treponema pallidum
  • Mycobacterium tuberculosis
  • HIV
  • Abscess in other anatomic location
• Pulmonary embolus
• Myocardial infarction
• Libman-Sacks endocarditis

Clinical Background

Endocarditis is an infection of the endocardium usually associated with infection of the cardiac valve leaflets.

Epidemiology

• Incidence – 3-4/100,000; incidence increases with age (up to 20/100,000)
• Age – mean 30-60 years, depending on population
• Sex – M>F, 2:1

Organisms

• Intravenous drug use (IVDU) – Staphylococcus spp, Streptococcus viridans
• Rheumatic heart disease – Streptococcus viridans
• Elderly with gastrointestinal neoplasms – Streptococcus bovis
• Prosthetic valves – Staphylococcus spp
• Health care associated infection – Enterococcus spp, Staphylococcus spp
• Culture negative disease – Coxiella, Bartonella, HACEK organisms (Haemophilus spp [esp. H. parainfluenzae], Aggregatibacter spp [A. aphrophilus, A. actinomycetemcomitans], Brucella, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae)
• Fungi – yeasts, molds

Risk Factors

• IVDU – sixty-fold increase
• Structural heart disease – rheumatic carditis, valvular stenosis, congenital heart disease
• Hemodialysis
• Cardiovascular prostheses, intravascular devices
• Diabetes mellitus
• Poor oral hygiene
• Human immunodeficiency virus (HIV)
• Prior episode of infective endocarditis

Pathophysiology

• Classification – native valve endocarditis and prosthetic valve endocarditis; right- versus left-sided valves
• Turbulent blood flow produced by abnormalities on valvular leaflets
  • In patients with rheumatic heart disease, mitral valve most commonly involved; aortic valve second most commonly involved
  • Right-sided endocarditis more common with IVDU
• Transient bacteremia occurs
  • Bacteria naturally adhere to abnormal tissue and form vegetations on the valve
  • Bacteria proliferate within the vegetations  

Clinical Presentation

• Constitutional – fever, anorexia, night sweats, weight loss
• Cardiovascular – new onset murmur, congestive heart failure, dysfunctional prosthetic valve
• Renal – glomerulonephritis
• Embolic phenomena
• Osler nodes – painful blue or purple nodules on the fingers, toes, palms, and soles
• Roth spots – retinal hemorrhages with central white spots
• Janeway lesions – nontender nodules on hands and feet
• Splinter hemorrhages – subungual linear hemorrhages on the long axis of the distal third of nail
• Complications
  • Valvular collapse with heart failure
  • Periannular extension of the infection into the adjacent myocardium
  • Rupture of the myocardium from extension
  • Embolization – highest with left-sided lesions
    • Stroke
  • Mycotic aneurysm
  • Splenic/hepatic abscesses
  • Intracardiac abscesses

Treatment

• Rapid initiation of antibiotics
• May require valvular replacement

Prevention

• Prophylaxis for high-risk patients before dental procedures (AHA, 2007)
  • Manipulation of gingival tissue periapical region
  • Perforated oral mucosa
  • Invasive procedure of the respiratory tract needing biopsy of respiratory mucosa or invasive procedure involving infected skin
• High-risk patients include the following
  • Previous infective endocarditis
  • Prosthetic valve
  • Unrepaired or incompletely repaired cyanotic congenital heart disease or repaired CHD within 6 months of previous repair
  • Valve disease in cardiac transplant patients
• No prophylaxis needed before gastrointestinal or genitourinary procedures

Pediatrics

Clinical Background

Epidemiology

• Incidence – lower than in adult population

Risk Factors

• Congenital heart disease
• Rarely – malignancy, osteomyelitis

Organisms

• Viridans streptococcus – rheumatic heart disease
• Staphylococcus epidermidis – nosocomial infection

Clinical Presentation

• Constitutional – lethargy, fever, malaise
• Cardiovascular – new onset murmur
• Adult manifestations such as Osler nodes and Janeway lesions uncommon
• Complications
  • Heart failure 
  • Intracardiac abscess
  • Embolization

Diagnosis

• Refer to Diagnosis tab

Indications for Laboratory Testing

• Tests generally appear in the order most useful for common clinical situations
• Click on number for test-specific information in the ARUP Laboratory Test Directory

Click the plus sign to expand the table of additional tests.

Test Name and Number	Comments
Organism Identification by 16S rDNA Sequencing 0060720 Method: 16S rDNA Sequencing
Coxiella burnetii (Q-Fever) Antibodies, IgG & IgM by IFA with Reflex to Titer 2003102 Method: Immunofluorescence Assay (Indirect Fluorescent Antibody)
Bartonella Species by PCR 0093057 Method: Qualitative Polymerase Chain Reaction
Rheumatoid Arthritis Panel 2003277 Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Immunoturbidimetry
Anti-Nuclear Antibodies (ANA), IgG by ELISA with Reflex to ANA, IgG by IFA 0050080 Method: Qualitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Indirect Fluorescent Antibody