From the Guidelines
The correct answer is Coxiella burnetii. According to the Modified Duke's Criteria for the Clinical Diagnosis of Infective Endocarditis, a single positive blood culture for Coxiella burnetii can account for a major criterion, as stated in the guidelines 1. This is because Coxiella burnetii, the causative agent of Q fever, is highly specific for endocarditis when detected in blood cultures, though it is difficult to isolate using standard blood culture techniques. The organism has a strong association with culture-negative endocarditis, and serological evidence of infection (particularly high IgG antibody titers against phase I antigen) is considered highly diagnostic.
Some key points to consider:
- The Modified Duke's Criteria are used to diagnose infective endocarditis, and they include major and minor criteria 1.
- A single positive blood culture for Coxiella burnetii is considered a major criterion, while other organisms typically require multiple positive blood cultures to fulfill a major criterion 1.
- The guidelines emphasize the importance of clinical judgment in diagnosing infective endocarditis, and the Modified Duke's Criteria should be used as a guide rather than a replacement for clinical judgment 1.
Overall, the evidence suggests that Coxiella burnetii is a major criterion for infective endocarditis with a single positive blood culture according to the Modified Duke's Criteria.
From the Research
Organism Considered a Major Criterion for Infective Endocarditis
- According to the Modified Duke's Criteria, a major criterion for Infective Endocarditis includes a positive blood culture for certain organisms, such as Staphylococcus aureus, with a single positive blood culture considered sufficient for diagnosis in certain cases 2, 3, 4, 5.
Specific Organisms
- Staphylococcus aureus is considered a major criterion for Infective Endocarditis with a single positive blood culture, as it is a common cause of the disease and can lead to severe complications 6, 2, 3, 4, 5.
- Other organisms, such as the HACEK group (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella spp.), can also cause Infective Endocarditis, but may require multiple positive blood cultures for diagnosis 6.
Diagnosis and Management
- The diagnosis of Infective Endocarditis relies on the Modified Duke Criteria, which include clinical, laboratory, and imaging findings, as well as the identification of the offending microorganism 6, 2, 5.
- Management of Infective Endocarditis typically involves prolonged antimicrobial therapy and may require surgical intervention to remove infected prosthetic material or repair damaged heart valves 6, 3, 4, 5.