Infectious Diseases in Critical Care Medicine

Definitive pathological diagnosis of IE is derived at by culturing organisms from an
endocardial vegetation, an embolized thrombus, or a myocardial abscess. Alternatively,
histological examination can confirm the diagnosis. Standard tissues gains have been
supplemented by DNA amplification techniques (187).
In 1994, Durack and colleagues developed criteria (The Dukes Criteria) to facilitate the
diagnosis of IE. These are based on the combined clinical, microbiological, and echocardio-
graphic findings for a given patient (146).
Major criteria include:

1. The presence of a continuous bacteremia (see above) with organisms typically
   involved in IE


2. Specific echocardiographic findings of IE
   a.An oscillating intracardiac mass on a valve or supporting structures or in the path of
   regurgitant jets or on an iatrogenic device
   b.Myocardial abscess
   c.New dehiscence of a prosthetic valve
   d.New valvular regurgitation

Minor criteria include:

1. Predisposing cardiac conditions or intravenous drug use


2. Fever greater than or equal to 38 8 C (100.4 8 F)


3. Vascular phenomena such as arterial emboli, septic pulmonary infarcts, mycotic
   aneurysms, intracranial hemorrhages, and Janeway lesions.


4. Immunological phenomena such as glomerulonephritis, Osler’s nodes, Roth spots,
   and rheumatoid factor.


5. Echocardiographic findings not meeting the above major echocardiographic criteria.


6. Positive blood cultures, not meeting above major criteria, or serological evidence of
   the presence of an organism typically involved in IE.

The definitive clinical diagnosis of IE is made by the presence of two major criteria or one
major and three minor criteria or five-minute criteria.

Table 9 American College of Cardiology/American Heart Association Guidelines for Echocardiography in Native
Valve and Prosthetic Valve Endocarditits

1. Indication Classa(native/prosthetic valve)


2. Detection and characterization of valvular lesions and their hemodynamic
   severity or degree of ventricular decompensationb

I/I

3. Detection of associated abnormalities (e.g., abscesses, shunts etc.)b I/I


4. Reevaluation of complicated endocarditis (e.g., virulent organisms, severe
   hemodynamic lesion, aortic valve involvement, persistent fever or
   bacteremia clinical change, or deterioration)

I/I

5. Evaluation of patients with high clinical suspicion of culture-negative
   endocarditisb

I/I

6. Evaluation of persistent bacteremia or fungemia without a known sourceb Ia/I


7. Risk stratification in established endocarditisb IIa/–


8. Routine reevaluation in uncomplicated endocarditis during antibiotic
   therapy

IIb/IIb

9. Evaluation of fever and nonpathalogical murmur without evidence of
   bacteremiac

III/IIa

aClass I: evidence and/or general agreement that an echocardiography is useful; Ila: conflicting evidence or

divergence of opinion about usefulness, but weight of evidence/opinion favor it; lib: usefulness is less well
established; 111: evidence or general opinion that echocardiography is not useful.
bTransesophegeal echocardiography (TEE) may provide incremental value in addition to information obtained by

transthoracic echocardiography (TTE). The role of TEE in first-line examination awaits further study.
cProsthetic valves-IIa: for persistent bacteremia; 111: for transient bacteremia.

Source: Adapted from Ref. 180

236 Brusch