Update on blood culture-negative endocarditis

Area of Science:

• Infectious Diseases
• Cardiology
• Microbiology

Background:

• Blood culture-negative endocarditis (BCNE) is a severe condition with diagnostic difficulties.
• Advances in molecular diagnostics and cardiac surgery have reduced the rate of non-documented infective endocarditis.
• BCNE is challenging due to prior antibiotic treatment, fastidious microorganisms, and intracellular bacteria.

Purpose of the Study:

• To classify the main categories of blood culture-negative endocarditis.
• To highlight diagnostic approaches for each category of BCNE.
• To discuss the role of molecular biology, cardiac surgery, and specific tests in diagnosing BCNE.

Main Methods:

• Classification of BCNE into three main categories.
• Review of diagnostic modalities including blood cultures, prolonged incubation, serological tests, and PCR.
• Discussion of common and rare causative pathogens for each BCNE category.

Main Results:

• BCNE is categorized into: 1) bacterial endocarditis with sterilized blood cultures, 2) endocarditis due to fastidious microorganisms, and 3) true blood culture-negative endocarditis (intracellular bacteria).
• Common pathogens include streptococci, staphylococci, enterococci, HACEK group, Gemella, Granulicatella, Abiotrophia, Propionibacterium acnes, and Candida.
• Intracellular bacteria like Bartonella sp., Coxiella burnetti, and Tropheryma whipplei require specific serological or PCR-based diagnostics.

Conclusions:

• Accurate diagnosis of BCNE relies on understanding its categories and employing appropriate diagnostic tools.
• Molecular biology and cardiac surgery have improved diagnosis, but specific tests are crucial for fastidious and intracellular pathogens.
• Non-infective endocarditis remains rare, primarily associated with marantic conditions or systemic diseases.