Infective endocarditis caused by slow-growing, fastidious, Gram-negative bacteria

Area of Science:

• Infectious Diseases
• Cardiology
• Microbiology

Background:

• Fastidious, slow-growing gram-negative rods can cause endocarditis, often affecting previously damaged heart valves.
• Bacteremia originating from the upper respiratory tract is a common source for these infections.

Observation:

• The clinical presentation of this endocarditis is typically subacute or chronic, mimicking Streptococcus viridans endocarditis.
• Despite antibiotic treatment, severe congestive heart failure (CHF) and systemic embolization are frequent complications, contributing to high morbidity and mortality.

Findings:

• Endocarditis due to Cardiobacterium hominis, Actinobacillus actinomycetemcomitans, and Haemophilus species may be more prevalent than previously thought.
• These infections are often missed due to inadequate culture techniques, particularly the need for specific methods to detect organisms with granular growth in broth.

Implications:

• Improved diagnostic accuracy through specialized culturing can lead to earlier recognition and management of this severe form of endocarditis.
• Recognizing the unique cultural requirements of these bacteria is essential for identifying culture-negative endocarditis cases.