What are the Modified Duke criteria for infective endocarditis?


Infective Endocarditis:

The Modified Duke criteria for the clinical diagnosis of infective endocarditis:

The diagnosis of infective endocarditis is established with certainty only when vegetations are examined histologically and microbiologically. Nevertheless, a highly sensitive and specific diagnostic schema-known as the modified Duke criteria-is based on clinical, laboratory and echocardiographic findings commonly encountered in patients with endocarditis. It has two types of criteria (see below).

A. Major criteria: 2 in number
1. Positive blood culture (3 ways)
a.Typical microorganism for infective endocarditis from two separate blood cultures (Viridans streptococci, Streptococcus gallacticus, HACEK group organisms, Staphylococcus aureus, or community-acquired enterococci in the absence of primary focus)

Or,

b.Persistently positive blood culture, defined as recover of a microorganism consistent with infective endocarditis from;

  • Blood cultures drawn > 12 hours apart; or
  • All of 3 or a majority of ≥4 separate blood cultures, with first and last drawn at least 1 hour apart

Or,

c.Single positive blood culture for Coxiella burnetii(Q fever) or phage I IgG antibody titer of >1: 800

2. Evidence of endocardial involvement (2 ways)
1.Positive echocardiogram (3 types of findings)
  • Oscillating intracardiac mass on valve or supporting structures or in the path of regurgitant jets or in implanted material, in the abscess of an alternative anatomical explanation, or
  • Abscess, or
  • New partial dehiscence of prosthetic valve


Or

2.New valvular regurgitation (increased or change in preexisting murmur not sufficient)


 From Davidson's (fig no mentioned)

B. Minor criteria:
  • Predisposition: predisposing heart conditions or injection drug use
  • Fever: ≥38.0°C (≥100.4°F)
  • Vascular phenomena: Major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrage, conjunctival hemorrhage, Janeway lesions
  • Immunlogic phenomena: glomerulonephritis, Osler’s nodes, Roth’s spots, rheumatoic factor
  • Microbiological evidence: positive blood culture but not meeting major criterion, as noted previously or, serological evidence of active infection with an organism consistent with infective endocarditis
  • Echocardiogram: findings consistent with infective endocarditis but not meeting a major criterion as noted above


According to duke criteria: Definite endocarditis is defined by documentation of two major criteria or of one major and three minor criteria or of five major criteria

In nutshell: The diagnosis of infective endocarditis is definite when:
  • A microorganism is demonstrated by culture of a specimen from a vegetation, an embolism or an intracardiac abscess
  • Active endocarditis is confirmed by histological examination of the vegetation or intracardiac abscess;
  • Two major clinical criteria, one major and three minor criteria, or five minor criteria are met (This is modified Duke Criteria)

Source:
  • Harrison’s Principles of Internal Medicine 2 volumes 19th Edition: 819 (1176)
  • Davidsons Principles and Practice of Medicine 23 edition; 554(531)
  • Kumar & Clark’s Clinical Medicine 9th Edition: 1019 (2514)

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