Question

While doing rounds one morning, you come upon a 42-year-old man suspected of having an infective endocarditis and currently undergoing an extensive workup. Which of the following represents the most definitive diagnosis of Infective Endocarditis based on Modified Duke Criteria?

1. 1 positive blood culture with Staphylococcus aureus with Osler's nodes and Roth spots

2. 2 positive blood cultures with Streptococcus pneumoniae with cutaneous hemorrhages and glomerulonephritis

3. Evidence of endocardial vegetation on echocardiography with Osler's nodes

4. 2 positive blood cultures with Staphylococcus aureus and development of a new regurgitant murmur

5. Fever >100.4 degrees Fahrenheit (38 degrees Celsius) with evidence of endocardial vegetation on echocardiography and glomerulonephritis

Answer 1

The most definitive diagnosis of Infective Endocarditis according to the Modified Duke Criteria would be two positive blood cultures with Staphylococcus aureus combined with the onset of a new regurgitant murmur.

Step-by-step explanation:

The most definitive diagnosis of Infective Endocarditis based on Modified Duke Criteria is option 4: 2 positive blood cultures with Staphylococcus aureus and the development of a new regurgitant murmur. According to the Modified Duke Criteria, definitive diagnosis is typically based on the presence of either two major criteria, one major criterion along with three minor criteria, or five minor criteria. Major criteria include positive blood cultures of organisms typical of infective endocarditis from two separate blood cultures, evidence of endocardial involvement with positive echocardiogram showing either a mass on a valve or supporting structures, abscess, or new partial dehiscence of prosthetic valve, and new valvular regurgitation. The development of a new regurgitant murmur indicates valvular damage which is a major criterion, in addition to two positive blood cultures with a common causative agent, S. aureus.