Description

• An infection primarily of the valvular endocardium and, occasionally, the mural endocardium
• System(s) affected: Cardiovascular; Endocrine/Metabolic; Hematologic/Lymphatic; Immunologic; Pulmonary; Renal/Urologic; Skin/Exocrine; Neurologic
• Synonym(s): Bacterial endocarditis; Subacute bacterial endocarditis; Acute bacterial endocarditis

Epidemiology

Incidence
In the US: 1.5–6.2/100,000; cumulative rate of endocarditis at 1 year after prosthetic valve replacement is 1.5–3.0%; at 5 years, 3–6%. Highest risk during 6-month period following valve replacement. Incidence is increased in the elderly.

Risk Factors

• Injection drug use, IV catheterization, certain malignancies (colon cancer)
• High-risk cardiac conditions:
  • Prosthetic cardiac valve; previous infective endocarditis (IE); congenital heart disease (CHD), such as unrepaired cyanotic CHD, including palliative shunts and conduits, repaired CHD with prosthetic device during the prior 6 months, repaired CHD with residual defects at or near the site of prosthetic material, cardiac transplantation recipients who develop valvulopathy (1)[B]

General Prevention

• Maintain good oral hygiene.
• Antibiotic prophylaxis is only recommended for people with cardiac conditions predicting the highest risk of adverse outcome from IE (1)[C]. Procedures requiring prophylaxis:
  • Oral/Upper respiratory tract: For any manipulation of gingival tissue or periapical region of teeth or perforation of the oral mucosa (1)[C], invasive respiratory procedures involving incision, or biopsy of the respiratory mucosa use amoxicillin 2 g PO (if penicillin-allergic, clindamycin 600 mg PO) 30–60 minutes before procedure or ampicillin 2 g IV/IM. For penicillin-allergic patients use clindamycin 600 mg IV, or cephalexin 2 g PO, or azithromycin/clarithromycin 500 mg PO, or cefazolin/ceftriaxone 1 g IV/IM 30 minutes before procedure. For pediatric doses, use amoxicillin 50 mg/kg PO; cephalexin 50 mg/kg PO; clindamycin 20 mg/kg PO; and ampicillin or ceftriaxone 50 mg/kg IM/IV.
  • GI/GU: Only consider coverage for enterococcus (with penicillin, ampicillin, piperacillin, or vancomycin) for patients with an established infection undergoing procedures (1)[B].
  • Cardiac valvular surgery or placement of prosthetic intracardiac/intravascular materials: Perioperative cefazolin 1–2 g IV 30 minutes preop, or vancomycin 15 mg/kg 60 minutes preop in the penicillin-allergic patient (1)[B]
  • Skin: Incision and drainage of infected tissue; use agents active against skin pathogens (e.g., cefazolin 1–2 g IV q8h or vancomycin 15 mg/kg q12h) if penicillin-allergic or if methicillin-resistant MRSA suspected.

Etiology

• Acute endocarditis: Staphylococcus aureus; Streptococcus groups A, B, C, G; S. pneumoniae; Staphylococcus lugdunensis; Enterococcus spp. (gram-positive); Haemophilus influenzae or parainfluenzae; Neisseria gonorrhoeae (gram-negative)
• Subacute endocarditis: α-Hemolytic streptococci (Viridans group strep), S. bovis, Enterococcus spp., S. aureus, S. epidermidis (gram-positive); HACEK organisms: Haemophilus aphrophilus or paraphrophilus, Actinobacillus (aggregatibacter) actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae
• Endocarditis in IV drug abusers (tricuspid valve): S. aureus, Enterococcus spp. (gram-positive); Pseudomonas aeruginosa, Burkholderia cepacia, other bacilli (gram-negative); Candida spp.
• Early prosthetic-valve endocarditis (<60 days after valve implantation): S. aureus, S. epidermidis (gram-positive); gram-negative bacilli; Fungi: Candida spp., Aspergillus spp.
• Late prosthetic-valve endocarditis (>60 days after valve implantation): α-Hemolytic streptococci, Enterococcus spp., S. epidermidis (gram-positive);Candida spp., Aspergillus spp.
• Culture-negative endocarditis: Bartonella quintana (homeless people); B. (cat owners); fastidious organism: Brucella spp., fungi, Coxiella burnetii (Q fever), Chlamydia trachomatis, C. psittaci, HACEK organisms; abiotrophia (formerly B₆-deficient streptococci); use of antibiotics prior to blood cultures