It Began to Murmur: Duke Criteria for Infective Endocarditis

Duke Clinical Criteria for the Diagnosis of Infective Endocarditis

1. Major Criteria
   • Positive blood culture for IE
     • Typical microorganism consistent with IE from 2 separate blood cultures, including the following: viridans streptococci, Streptococcus bovis, or HACEK group, or community-acquired Staphylococcus aureus or enterococci in the absence of a primary focus
     • Microorganisms consistent with IE from persistently positive blood cultures defined as: 2 positive cultures of blood samples drawn >12 hours apart or all of 3 or a majority of 4 separate blood cultures
   • Positive echocardiogram for IE
     • Oscillating intracardiac mass on valve, abscess, or new partial dehiscence of prosthetic valve
     • Sensitivity of TTE is highest in IVDU (88% to 94%) who more often have larger vegetations, a preponderance of right-sided lesions, and patients are younger with a favorable acoustic precordial window.
   • New valvular regurgitation

2. Minor Criteria
   • Predisposition: Prior heart condition or injection drug use
   • Fever: Temperature >38°C (100.4°F)
   • Vascular phenomena: Major arterial emboli, septic pulmonary conjunctival hemorrhages, or Janeway lesions
   • Immunologic phenomena: Glomerulonephritis, Osler nodes, Roth spots, or rheumatoid fever
   • Microbiologic evidence: Positive blood culture but does not meet a major criterion or serologic evidence of active infection with organism consistent with IE

1. Definite IE
   • 2 major criteria
   • 1 major and 3 minor criteria
   • 5 minor criteria
2. Possible IE
   • Findings consistent with IE that fall short of “definite” but are not “rejected”
3. Rejected IE (1 of these)
   • Firm alternate diagnosis for manifestations of endocarditis
   • Resolution of manifestations of endocarditis with antibiotic therapy for 4 days or less
   • No pathologic evidence of IE at surgery or autopsy after antibiotic therapy for ≤ 4 days

1) Heart murmur

2) Janeway Lesions: Painless macules located on the thenar and hypothenar eminences of the hands and feet. Pathologically, these lesions are microabscesses of the dermis caused by septic emboli.

3) Osler Nodes: Small, tender nodules that range from red to purple and are in the pulp spaces of the terminal phalanges of the fingers and toes, the soles of the feet, and the thenar and hypothenar eminences of the hands.

4) Roth Spots: Oval-shaped hemorrhages with white centers present on the retina.

5) Splinter Hemorrhages: Red lines of blood running under the nails in the direction of nail growth that look like splinters and may be caused by vasculitis or microemboli.

• The Duke criteria have a sensitivity of about 80%
• Validation studies of the Duke criteria have found a specificity of 99% and a negative predictive value of 92%, giving them good diagnostic power.

Our patient is a young IVDU presenting with fever, heart murmur, and rash. Transthoracic echocardiogram showed vegetations on the tricuspid valve. He meets 1 major and 3 minor Duke criteria which suggests definite IE. Although the blood cultures are pending, Vancomycin, nafcillin, and gentamicin are started in the ED, and he is admitted to medicine with a presumptive diagnosis of IE. A transesophageal echocardiogram confirms the ED findings, and blood cultures grow MRSA. The patient has a PICC line placed and receives antibiotics for 6 weeks.