Bacterial Endocarditis Guidelines

Definition and Pathophysiology

Bacterial endocarditis is an endovascular microbial infection of heart valves, intracardiac structures, large intrathoracic vessels, and intracardiac foreign bodies/prosthetic material, characterized by the formation of vegetations composed of platelets, fibrin, microorganisms, and inflammatory infiltrate, according to the European Heart Journal 1, 2
The characteristic pathological lesion is a vegetation, although destruction, ulceration, or abscess formation may develop as the infection progresses, as reported in the European Heart Journal 1

The most common causative organisms include Staphylococci, Streptococci, Enterococci, HACEK organisms, and Fungi, as stated in Circulation 3
High-risk factors for IE include prosthetic valves, previous IE, complex congenital heart disease, and surgically constructed systemic or pulmonary conduits, as identified by the European Heart Journal 1 and the European Society of Cardiology guidelines 2
Moderate-risk factors include acquired valvular disease, mitral valve prolapse with regurgitation, non-cyanotic congenital heart disease, hypertrophic cardiomyopathy, and bicuspid aortic valve, as listed by the European Heart Journal 1
IV drug use represents a significant but secondary risk factor for IE, with an estimated incidence of 1.5 to 3.3 cases per 1000 person-years 3
The incidence of IE associated with underlying rheumatic heart disease has decreased in developed countries, while in developing countries, rheumatic valve disease remains a significant risk factor for IE, according to the European Society of Cardiology 2
The average age of patients with IE has increased, with a peak incidence of 14.5 episodes/100,000 person-years in patients between 70-80 years, as reported by the European Society of Cardiology 2

Common clinical manifestations include fever, new regurgitant heart murmur, embolic phenomena, and immunological phenomena, such as Roth spots, Janeway lesions, and Osler nodes, as described in the European Heart Journal 1, 2
Diagnosis is based on the modified Duke criteria, which include positive blood cultures, echocardiographic evidence of endocardial involvement, and minor criteria such as predisposing heart condition, fever, and vascular phenomena, as reported in Circulation 3 and the European Heart Journal 2
Echocardiography, including transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE), is a crucial diagnostic tool, with TEE having higher sensitivity for detecting vegetations, abscesses, and valve perforations, according to Circulation 3
Blood cultures are the cornerstone of diagnosis, with three separate samples taken 30 minutes apart, before starting antibiotics, and positive in 85-90% of cases, as recommended by the European Heart Journal 2

Treatment requires prolonged antimicrobial therapy with high doses to penetrate vegetations, as stated in Circulation 3 and the European Heart Journal 2
The American Heart Association recommends penicillin G 12-18 million U/day IV in 6 divided doses for 4 weeks, or ceftriaxone 2g/day IV for 4 weeks, as reported in Circulation 3
Empiric therapy should be based on clinical presentation and epidemiology, and consider unusual pathogens such as Bartonella, Coxiella, and Brucella, according to Circulation 3
Antibiotic prophylaxis is recommended for patients at high risk of IE, including those with prosthetic valves, previous IE, complex congenital heart disease, and surgically constructed systemic or pulmonary conduits, before undergoing dental procedures with a high risk of bleeding, as recommended by the European Heart Journal 1
Amoxicillin 2g orally (or 50 mg/kg for children) 1 hour before the procedure, or clindamycin 600 mg orally (or 20 mg/kg for children) 1 hour before the procedure, is suggested for patients allergic to penicillin, as recommended by the European Heart Journal 1
Surgical intervention is recommended for emergency cases, such as severe heart failure or cardiogenic shock, urgent cases, such as persistent heart failure or uncontrolled infection, and elective cases, such as IE due to fungi or multiresistant microorganisms, as recommended by the European Heart Journal 2 and the Circulation journal 4

Major complications include congestive heart failure, periannular abscesses, systemic embolization, neurological complications, mycotic aneurysms, and splenic abscess, as described in the European Heart Journal 1
Approximately 50% of patients require surgery, with indications including severe heart failure, persistent heart failure, uncontrolled infection, and large vegetations with embolic events, as reported in the European Heart Journal 1 and Circulation 4
If untreated, bacterial endocarditis is universally fatal, and even with appropriate treatment, in-hospital mortality remains high (15-20%), particularly with certain pathogens, prosthetic valve involvement, or complications such as heart failure, according to the European Heart Journal 1 and the Circulation journal 4
Cardiac rehabilitation after surgery is recommended, including treatment of residual valvular sequelae, management of neurological complications, physical rehabilitation in case of embolic events with sequelae, periodic echocardiographic follow-up, education on dental hygiene and prevention of bacteremia, psychological support, and secondary prevention in patients with a history of IE, as recommended by the European Heart Journal 2