ICD 10 Code = I33.0
General Measures
Bed rest.
Early surgical intervention in acute fulminant and prosthetic valve endocarditis is often indicated.
Consider surgery if there is heart failure, embolism, large vegetations on echocardiography, heart block, evidence of persistent infection despite antibiotics or renal impairment. Refer these patients promptly.
Medicine Treatment
Treat accompanying complications, e.g. cardiac failure. Such treatment should not delay referral.
Antibiotic Therapy
It is essential to do at least 3 blood cultures, taken by separate venipunctures, before starting antibiotics.
In patients with subacute presentation and no haemodynamic compromise, wait for the results of blood culture before starting antibiotics.
Empiric treatment is indicated in patients with a rapidly fulminant course or with severe disease only.
Aminoglycoside therapy should be monitored with trough levels for safety.
Duration of therapy given is the minimum and may be extended based on the response (clinical and laboratory).
Severe penicillin-allergic patients, or methicillin resistant staphylococcal infections
ICD 10 = Z88.0
Vancomycin, IV, 20 mg/kg 12 hourly, is the antibiotic of choice.
It is essential to monitor trough concentrations of vancomycin regularly and adjust doses accordingly, starting after the third dose.
Empiric therapy for Infective endocarditis
Native Valve (natural valves):
- Benzylpenicillin (penicillin G), IV, 5 MU 6 hourly for 4 weeks. AND
- Gentamicin, IV, 1.5 mg/kg 12 hourly for 2 weeks. See Gentamicin prescription guidance.
If staphylococcus infection is suspected (acute onset), Add:
- Cefazolin, IV, 2 g, 8 hourly.
Prosthetic Valve:
- Vancomycin, IV, 20 mg/kg 12 hourly for 6 weeks. AND
- Rifampicin, oral, 7.5 mg/kg 12 hourly for 6 weeks. AND
- Gentamicin, IV, 1.5 mg/kg 12 hourly for 2 weeks.
Refer all cases of prosthetic valve infective endocarditis.
Directed Therapy (Native Valve)
| Streptococcal | |
| Fully susceptible to penicillin. MIC: <0.2 mg/L. | Benzylpenicillin (penicillin G), IV, 5 MU 6 hourly for 4 weeks. |
| Moderately susceptible. MIC: 0.12–0.5 mg/L. | Benzylpenicillin (penicillin G), IV, 5 MU 6 hourly for 4 weeks, AND. Gentamicin, IV, 1.5 mg/kg 12 hourly for 2 weeks. |
| Moderately resistant MIC: 0.5–4 mg/L Enterococci and Abiotrophia spp. (Nutritionally variant streptococci). | Benzylpenicillin (penicillin G), IV, 5 MU 6 hourly for 4 weeks, AND. Gentamicin, IV, 1.5 mg/kg 12 hourly for 4 weeks. 6 weeks of therapy may be required in cases with a history of >3 months, or mitral or prosthetic valve involvement. |
| Fully resistant MIC: >4 mg/L | Vancomycin, IV, 20 mg/kg 12 hourly for 6 weeks, AND. Gentamicin, IV, 1.5 mg/kg 12 hourly for 6 weeks. |
| Enterococci | |
| Fully susceptible to penicillin. MIC: <4 mg/L | Benzylpenicillin (penicillin G), IV, 5 MU 6 hourly for 4 weeks. |
| Moderately resistant MIC: 0.5–4 mg/L Enterococci and Abiotrophia spp. (nutritionally variant streptococci). | Benzylpenicillin (penicillin G), IV, 5 MU 6 hourly for 4 weeks, AND. Gentamicin, IV, 1 mg/kg 8 hourly for 2 weeks. 6 weeks of therapy may be required in cases with a history of >3 months, or mitral or prosthetic valve involvement. |
| Penicillin-resistant MIC ≥ 4 mg/L or significant ß-lactam Allergy and Sensitive to vancomycin MIC: ≤4 mg/L | Refer. |
| Staphylococcal (cloxacillin/methicillin sensitive) | |
| S. aureus | Cefazolin, IV, 2g 8 hourly for 4 weeks. If necessary, add: Gentamicin, IV, 6 mg/kg daily for the first 3–5 days. The benefit of adding an aminoglycoside has not been established. |
| Coagulase-negative staphylococci | Consult expert opinion on correct diagnosis in this setting. |
| Staphylococcal (cloxacillin/methicillin resistant) or methicillin sensitive with significant beta-lactam allergy | |
| S. aureus | Vancomycin, IV, 20 mg/kg 12 hourly for 4 weeks. |
| Coagulase-negative staphylococci | Consult expert on correct on antibiotic choice |
Directed Therapy for Prosthetic Valve Endocarditis
Duration of therapy is usually a minimum of at least 6 weeks.
Seek expert opinion on antibiotic choice and the need for referral for repeat cardiac surgery early in the course of the treatment.
Endocarditis prophylaxis
Cardiac conditions
Patients with the following cardiac conditions are at high risk of developing infective endocarditis:
- Patients with prosthetic heart valves.
- Structural congenital heart disease, including surgically corrected or palliated structural conditions, but excluding isolated atrial septal defect, fully repaired ventricular septal defect or fully repaired patent ductus arteriosus.
- Patients who have suffered previous endocarditis.
Procedures requiring prophylaxis
Antibiotic prophylaxis is recommended for all dental procedures that involve manipulation of either the gingival tissue or the peri-apical region of the teeth.
Antibiotic prophylaxis is not recommended for patients who undergo a gastrointestinal or genito-urinary procedure.
Prophylaxis (ICD 10 = Z29.2)
Maintain good dental health.
This is the most important aspect of prophylaxis.
Refer all patients to a dental clinic/dental therapist for assessment and ongoing dental care.
Amoxicillin, oral, 2 g one hour before the procedure.
If patient cannot take oral:
Ampicillin, IV/IM, 2 g one hour before the procedure.
Severe penicillin allergy (Z88.0):
Clindamycin, oral/IV, 600 mg one hour before the procedure.
The NICE review noted the lack of a consistent association between interventional procedures and development of infective endocarditis, and that the efficacy of antibiotic prophylaxis is unproven.
It further commented that because the antibiotic is not without risk, there is a potential for a greater mortality from severe hypersensitivity than from withholding antibiotics.
Practitioners need to weigh the risk of the underlying heart disease (particularly previous successfully treated endocarditis) and the essential need for ongoing antibiotic stewardship.
For further reading, check Infective Endocarditis.