bubble_chart Overview

Infective endocarditis, previously known as bacterial endocarditis, has seen changes in its clinical manifestations in recent years due to the widespread use of antibiotics and the evolution of clinical microbiology. The course of the disease has prolonged, making it difficult to clearly distinguish between acute and subacute forms. Additionally, the causative agents now include not only bacteria but also fungi and viruses. Therefore, the condition is now referred to by the broader term infective endocarditis.

bubble_chart Auxiliary Examination

1. Routine examination: There is progressive anemia and leukocytosis, predominantly neutrophilic, with an increased erythrocyte sedimentation rate. Serum globulin levels are elevated, and in some cases, the albumin-to-globulin ratio is inverted. Some patients test positive for wind-dampness factor. Proteinuria and microscopic hematuria may be present.
2. Blood culture: Often the key to diagnosis, the positivity rate is higher when multiple blood cultures are performed within the first 1–2 days compared to cultures spread over several days.
3. Echocardiography: Two-dimensional echocardiography can detect the size of vegetations and dynamic changes in valve membrane function, the latter also aiding in the assessment of treatment efficacy.

bubble_chart Diagnosis

1. Systemic infection: The onset is generally slow, with only irregular fever, fatigue, loss of appetite, weight loss, and pale complexion, or skin and mucosal petechiae may be observed. Infections caused by highly virulent pathogens such as Staphylococcus aureus often have an acute onset, with systemic symptoms such as chills, high fever, night sweats, and weakness, primarily presenting as septicemia. Complications may include pneumonia, pericarditis, peritonitis, and osteomyelitis, as well as abscesses in organs such as the liver and kidneys. Splenomegaly is usually present.
2. Cardiac manifestations: If there is a preexisting congenital heart disease with murmurs, the nature of the murmur may change due to cardiac valve vegetations, becoming louder and harsher. In cases without preexisting murmurs, new murmurs may appear, characterized by a high pitch and variability. Valve lesions, toxic myocarditis, or myocardial abscesses can lead to congestive heart failure or cardiogenic shock.
3. Embolic manifestations: Emboli originating from the right heart due to congenital heart disease often lead to embolic pneumonia, presenting with severe chest pain, dyspnea, hemoptysis, and recurrent episodes within a short period. In patients with preexisting rheumatic valvular disease, vegetations typically occur in the left heart, leading to embolic phenomena in the brain, kidneys, spleen, skin, and limbs. Cerebral embolism manifests as headache, vomiting, hemiplegia, aphasia, or even unconsciousness. Meningitis caused by embolism often yields negative cerebrospinal fluid cultures, with normal glucose and chloride levels, requiring careful differentiation from tuberculous or viral meningitis. Renal embolism presents with hematuria, bacteriuria, and lumbago. Skin petechiae are commonly seen in the conjunctiva, oral mucosa, and chest skin, appearing in small numbers but holding diagnostic significance.

bubble_chart Treatment Measures

(1) General Treatment

Bed rest, enhanced nutrition, and maintenance of water and electrolyte balance are essential. If necessary, small, multiple blood transfusions should be administered to boost the body's resistance. (2) Anti-infection Treatment

Selecting sensitive and effective antibiotics, adhering to sufficient dosage and a prolonged treatment course, is crucial. It is preferable to use two antibiotics with positive drug sensitivity tests, administered via intravenous drip supplemented with intramuscular injection, for a minimum course of 4–6 weeks.

1. - **Streptococcus viridans**: Penicillin G 250,000 U/kg daily, administered every 4 hours via intravenous drip; gentamicin 3–6 mg/kg daily may be added, administered intramuscularly for 2–4 weeks.
2. - **Enterococcus**: Ampicillin 300 mg/kg daily, administered every 6 hours via intravenous drip, plus gentamicin 3–6 mg/kg daily, administered intramuscularly every 8 hours; alternatively, cefalotin 80–160 mg/kg daily, administered every 6 hours via intravenous drip; or cefazolin 50–100 mg/kg daily, administered every 8 hours via intravenous drip.
3. - **Gram-negative bacilli**: Cefuroxime (Zinacef) 70–150 mg/kg daily, administered every 8 hours via intravenous drip.
4. - **Staphylococcus aureus**: Oxacillin 200 mg/kg daily, administered every 4 hours via intravenous drip, plus gentamicin 3–6 mg/kg daily, administered intravenously every 8 hours; alternatively, cefazolin 50–100 mg/kg daily, administered intravenously every 8 hours.
5. - **Pseudomonas aeruginosa**: Ceftazidime (Fortum) 100–150 mg/kg daily, administered intravenously every 8–12 hours.
6. - **Fungal infections**: Amphotericin B, starting with an intravenous dose of 0.1 mg/kg daily, then increasing by 0.05–0.1 mg/kg daily until reaching 1 mg/kg, administered once daily or every other day.

The drug should be dissolved in 5% glucose solution, with an optimal concentration of 0.1 mg/ml. Normal saline should not be used as it may cause precipitation. Intravenous administration must last at least 4–6 hours. Side effects are generally mild, but some cases may experience shivering, fever, headache, anorexia, or nausea, especially during the first dose. To alleviate reactions, aspirin or antihistamines may be given 3 hours before or after treatment or at the end of treatment. If ineffective, 25 mg of hydrocortisone may be administered intravenously before each dose. Blood urea nitrogen should be monitored regularly before and during treatment. If it rises to 50 mg/dl, the dosing interval may be extended to every other day. If levels remain elevated, treatment should be discontinued until concentrations approach normal. If levels normalize within a few days, treatment may resume at the previous dose. If normalization takes longer, treatment should restart at a reduced dose. Blood potassium should also be monitored regularly, as hypokalemia is common and can be corrected with oral potassium supplementation. The treatment course generally lasts 4 weeks. Additionally, 5-fluorocytosine, an antifungal agent for deep fungal infections, may be combined with amphotericin B to enhance efficacy. The dose is 50–150 mg/kg daily, administered via slow intravenous drip, or as a 1% solution (250–500 ml) infused over 8 hours.

(3) Surgical Treatment

For cases where medical treatment fails to control the condition and congenital heart disease (e.g., patent ductus arteriosus, ventricular septal defect) coexists, procedures such as duct ligation and defect repair should be performed.