From the Guidelines
The most common bacterial species causing infective endocarditis (IE) is Staphylococcus aureus. This gram-positive bacterium has emerged as the predominant causative organism in both community-acquired and healthcare-associated infective endocarditis cases, as supported by the American Heart Association guidelines 1. S. aureus possesses several virulence factors that facilitate endocardial infection, including adhesins that allow attachment to cardiac valves, the ability to form biofilms, and production of various toxins that damage host tissues. The bacterium can enter the bloodstream through skin infections, intravenous drug use, or healthcare-related procedures, and has a particular propensity to adhere to both native and prosthetic heart valves.
Some key points to consider when managing IE caused by S. aureus include:
- The increasing prevalence of methicillin-resistant strains (MRSA) has further complicated treatment approaches, often requiring vancomycin or newer antibiotics like daptomycin for effective management 1.
- S. aureus endocarditis tends to present with more acute symptoms and carries a higher mortality rate compared to IE caused by other organisms.
- Other bacterial species, such as streptococci and enterococci, can also cause IE, but S. aureus is the most common and virulent species, as noted in the guidelines 1.
- The management of IE requires a comprehensive approach, including antimicrobial therapy, management of complications, and prevention of future episodes, as outlined in the American Heart Association guidelines 1.
From the Research
Causative Agents of Infective Endocarditis
The most common bacterial species causing Infective Endocarditis (IE) is:
Characteristics of Staphylococcus aureus IE
Some key characteristics of IE caused by Staphylococcus aureus include:
- High mortality rate, approximately 20% to 40% 5
- Association with embolic complications in up to 40% of patients 5
- Increasing resistance to antibiotics, especially methicillin 5
- Commonly originates from nosocomial sources, such as intravenous and arterial catheters, pacemaker leads, and prosthetic valves 5
Diagnosis and Treatment of IE
Diagnosis of IE typically involves:
- Blood cultures, with three sets of cultures obtained more than 6 hours apart and from separate sites before starting antibiotics 3
- Echocardiography, with transesophageal echocardiography having a higher sensitivity than transthoracic echocardiography 6 Treatment of IE usually involves antibiotic therapy, with vancomycin being a common choice for native valve IE and vancomycin and gentamicin being used for prosthetic valve endocarditis 3