Endocarditis is an infection of the endocardium usually associated with infection of the cardiac valve leaflets. Blood cultures are generally used for diagnosis, and are very sensitive for most organisms.

  • Diagnosis
  • Background
  • Pediatrics
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • Risk factors and appropriate clinical presentation

Criteria for Diagnosis

Laboratory Testing

  • CBC – frequently shows leukocytosis and left shift toward immature cell forms
  • Blood cultures – 3 sets from separate venipuncture sites; first and last set at least 1 hour apart
    • Perform prior to antibiotic administration
    • Very sensitive for most organisms
  • C- reactive protein (CRP)
  • For blood culture-negative disease, consider
    • Coxiella – antibody testing
    • Bartonella – polymerase chain reaction (PCR)
    • Brucella – culture, antibody testing
    • HACEK organisms (Haemophilus spp, Aggregatibacter spp [A. aphrophilusA. actinomycetemcomitans], Cardiobacterium hominisEikenella corrodensKingella kingae)
      • Cardiobacterium hominis
      • Eikenella corrodens
      • Kingella kingae
    • Antinuclear antibodies (ANA)/rheumatoid arthritis (RA)
      • RA may be less positive
    • Unusual causes – Tropheryma whipplei, fungi (yeastsmolds)
  • Urine analysis – may demonstrate hematuria, proteinuria, pyuria, red cell casts

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
      • Sensitivity dependent on vegetation size – if >10 mm, test is 100% sensitive
      • Prosthetic values may be better visualized with TTE
    • TEE
      •  Use in patients with high clinical suspicion and negative TTE
      •  Very sensitive – negative study has negative predictive value of 90%

Differential Diagnosis


  • Incidence – 3-10/100,000; incidence increases with age (up to 20/100,000)
  • Age – mean 30-60 years, depending on population
  • Sex – M>F, 3:1 to 9:1


  • Variety of organisms – Staphylococcus and Streptococcus spp account for most cases
  • Specific medical condition associations
    • Intravenous drug use (IVDU) – Staphylococcus spp, Streptococcus anginosus group
    • Rheumatic heart disease – Streptococcus anginosus group
    • Elderly with gastrointestinal neoplasms – Streptococcus bovis
    • Healthcare-associated infectionEnterococcus spp, Staphylococcus spp
    • Prosthetic valves – Staphylococcus spp
    • Culture negative disease – CoxiellaBartonella, BrucellaHACEK organisms (Haemophilus spp, Aggregatibacter spp [A. aphrophilusA. actinomycetemcomitans], Cardiobacterium hominisEikenella corrodensKingella kingae)
    • Fungi – yeastsmolds
      • Usually 2-3 months after left ventricular assist device (LVAD) implantation
      • Immunocompromised patients

Risk Factors

  • IVDU
  • Structural heart disease – rheumatic carditis, valvular stenosis, congenital heart disease, prosthetic heart valves
  • Hemodialysis
  • Cardiovascular prostheses, intravascular devices
  • Poor dentition
  • HIV
  • Prior episode of infective endocarditis (IE)
  • ​Age >60 years


  • Classification
    • Native valve endocarditis, prosthetic valve endocarditis, and nonvalvular device endocarditis (eg, pacemaker, LVAD)
    • Right- versus left-sided valves
    • Community versus healthcare acquired
  • 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
    • Patients with cardiac-device related IE may only have these symptoms normally
  • 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 (rare)
  • Roth spots – retinal hemorrhages with central white spots (rare)
  • Janeway lesions – nontender nodules on hands and feet (rare)
  • 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


Clinical Background


  • Incidence – lower than in adult population

Risk Factors

  • Congenital heart disease
    • Highest risk in cyanotic heart disease, endocardial cushion defects, high velocity jets
  • Indwelling catheters
  • Rarely – malignancy, osteomyelitis


  • Streptococcus anginosus group – 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


  • Refer to Diagnosis section
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.

CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Blood Culture 0060102
Method: Continuous Monitoring Blood Culture/Identification


Testing is limited to the University of Utah Health Sciences Center only

Low volume will result in decreased recovery of pathogens

C-Reactive Protein 0050180
Method: Quantitative Immunoturbidimetry


Baddour LM, Wilson WR, Bayer AS, Fowler VG, Bolger AF, Levison ME, Ferrieri P, Gerber MA, Tani LY, Gewitz MH, Tong DC, Steckelberg JM, Baltimore RS, Shulman ST, Burns JC, Falace DA, Newburger JW, Pallasch TJ, Takahashi M, Taubert KA, Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease in the Young, Councils on Clinical Cardiology, Stroke, and Cardiovascular Surgery and Anesthesia, American Heart Association, Infectious Diseases Society of America. Infective endocarditis: diagnosis, antimicrobial therapy, and management of complications: a statement for healthcare professionals from the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease in the Young, Circulation. 2005; 111(23): e394-434. PubMed

Choosing Wisely. An initiative of the ABIM Foundation. [Accessed: Nov 2017]

Durack DT, Lukes AS, Bright DK. New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings. Duke Endocarditis Service. Am J Med. 1994; 96(3): 200-9. PubMed

Wilson W, Taubert KA, Gewitz M, Lockhart PB, Baddour LM, Levison M, Bolger A, Cabell CH, Takahashi M, Baltimore RS, Newburger JW, Strom BL, Tani LY, Gerber M, Bonow RO, Pallasch T, Shulman ST, Rowley AH, Burns JC, Ferrieri P, Gardner T, Goff D, Durack DT, American Heart Association. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Cou J Am Dent Assoc. 2008; 139 Suppl: 3S-24S. PubMed

General References

Cahill TJ, Prendergast BD. Infective endocarditis. Lancet. 2016; 387(10021): 882-93. PubMed

Calabrese F, Carturan E, Thiene G. Cardiac infections: focus on molecular diagnosis. Cardiovasc Pathol. 2010; 19(3): 171-82. PubMed

Duke Criteria for Infective Endocarditis (IE). MedicalCRITERIA.com. [Last updated: Aug 2014; Accessed: Feb 2017]

McDonald JR. Acute infective endocarditis. Infect Dis Clin North Am. 2009; 23(3): 643-64. PubMed

Nataloni M, Pergolini M, Rescigno G, Mocchegiani R. Prosthetic valve endocarditis. J Cardiovasc Med (Hagerstown). 2010; 11(12): 869-83. PubMed

Pierce D, Calkins BC, Thornton K. Infectious endocarditis: diagnosis and treatment. Am Fam Physician. 2012; 85(10): 981-6. PubMed

Que Y, Moreillon P. Infective endocarditis. Nat Rev Cardiol. 2011; 8(6): 322-36. PubMed

Thanavaro KL, Nixon JV. Endocarditis 2014: an update. Heart Lung. 2014; 43(4): 334-7. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Medical Reviewers

Last Update: October 2017