What is infective endocarditis? Infective endocarditis occurs when bacteria are present in the bloodstream and multiply in the heart, forming clumps on the heart valves and causing valve destruction or even abscesses within the heart muscle. Patients may present with fever, heart murmurs, splenomegaly, and embolism caused by the dislodgement of bacterial masses. Early diagnosis and treatment of endocarditis is important because the disease is aggressive and can lead to death in severe cases. Predisposing factors The people most susceptible to endocarditis are those with congenital heart disease, because of valve disease or atrial or ventricular septal defects, and the presence of high velocity blood flow and turbulence in the heart, causing endothelial breakdown and making it easy for bacteria to adhere and multiply. Patients with foreign body implants in the heart, such as prosthetic valve replacements and patch implants, are also susceptible to endocarditis. In addition, the presence of a more serious infection somewhere in the body makes it easier for bacteria that enter the bloodstream to colonize the heart when the body is declining. There are also addicts who abuse drugs intravenously, who use unclean syringes and injection water, and therefore are prone to a high incidence of endocarditis in these groups. Clinical manifestations The most common clinical manifestation is fever, but it is nonspecific. Other manifestations include a new heart murmur and a change in the existing heart murmur. In addition, in some patients, there may be bleeding spots on the fundus (Roche’s spots), petechiae with pressure on the fingers and toes (Osler’s nodes), and painless skin lesions on the palms of the hands and feet (Janeway’s spots). Examination Leukocyte count >12 000/mm, anemia, hematuria, and positive blood cultures in 2 out of 3 occasions. Electrocardiography, which reveals conduction block, often suggests spread of infection or the formation of a perivalvular abscess. Cardiac ultrasound is important for the diagnosis of endocarditis. Positive ultrasound findings include redundancy, perivalvular leakage, intracardiac sinus tracts, and abscess formation. Diagnosis The diagnostic criteria established by Duke University (referred to as the Duke criteria) are currently used internationally. The Duke criteria include Primary criteria Positive blood cultures: 2 positive blood culture results for typical bacteria, detection of Streptococcus straw green, Streptococcus bovis, HACEK group, and Staphylococcus aureus; persistent positive blood cultures, i.e., the same bacteria detected in blood cultures more than 12 hours apart, or 3 of all 3 blood cultures or 4 positive blood cultures (more than 1 hour between the first and last). Positive cardiac ultrasound: finding of redundancy in the valve, tendon cords, on implant material, in the regurgitant bundle pathway, abscesses, new perivalvular leaks. Secondary criteria: Susceptibility factors: presence of cardiac susceptibility, intravenous drug abuse Fever: body temperature over 38°C. Vascular manifestations: arterial embolism, infected pulmonary infarction, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhage, Janeway’s spot. Immunological manifestations: glomerulonephritis, Osler’s node, Roche’s spot, positive rheumatoid factor. Microbiology: positive blood cultures but not meeting major criteria. Cardiac ultrasound: positive results but not meeting major criteria, new onset heart failure. Conduction block: new onset of conduction block. Surgical treatment Surgical indications: The vast majority of patients with ineffective antibiotic therapy and hemodynamic instability require surgical treatment. Severe valvular regurgitation with or without congestive heart failure. Failure to control sepsis with adequate antibiotic therapy. Presence of drug-resistant bacteria. Endocarditis caused by mycobacteria, Staphylococcus aureus, and Gram-staining-negative bacteria. Perivalvular abscess, spread of infection to the fibrous body, or formation of intracardiac sinus tracts. New-onset conduction block. A superfluous organism greater than 1 cm, which is mobile and prone to dislodging and embolization. Post-surgical treatment Usually, antibiotic therapy is also required for 4 to 6 weeks after surgery.