Infective Endocarditis: Etiology, Pathophysiology, Pathology, Diagnosis, and Complications

Etiology of Infective Endocarditis

Infective endocarditis (IE) is a life-threatening infection of the endocardium, typically affecting the heart valves. It is caused by pathogenic microorganisms that enter the bloodstream and colonize the cardiac tissue.

Risk Factors

• Presence of prosthetic heart valves
• Congenital heart disease
• Intravenous drug use
• Previous history of endocarditis
• Immunosuppression (e.g., HIV, chemotherapy)

Causative Microorganisms

The most common microorganisms responsible for IE include:

• Staphylococcus aureus – Most common in intravenous drug users
• Streptococcus viridans – Common in patients with underlying valvular disease
• Enterococcus species – Often associated with gastrointestinal or genitourinary infections
• HACEK organisms – Rare but significant contributors to IE

Pathophysiology

IE develops when microorganisms adhere to the damaged endocardium and form vegetations. These vegetations can lead to embolic complications and systemic inflammatory responses.

Diagnosis

Diagnosis is based on clinical findings, imaging studies, and microbiological evidence. The Duke criteria are commonly used for IE diagnosis.

Complications

• Heart failure
• Septic embolism
• Stroke
• Valvular destruction

Conclusion

Early diagnosis and appropriate antimicrobial therapy are critical for improving patient outcomes. Preventative measures, such as antibiotic prophylaxis for at-risk individuals, play a crucial role in reducing incidence.