Cardiovascular: infective endocarditis

General information

The definitive treatment regimen depends on the causative organism, its minimum inhibitory concentration (MIC) to the chosen antimicrobial(s), and the nature of the infected valve (native/prosthetic).
The most common bacteria in the classic presentation of subacute bacterial endocarditis are streptococci or enterococci, the majority of which are susceptible to amoxicillin.
In presentations where the onset of disease has been more acute or where recreational drugs have been injected, S. aureus is the more likely pathogen, and pending ID and susceptibility testing empirical cover for MRSA with vancomycin is warranted.
In prosthetic valve endocarditis the possible range of pathogens is wide and includes coagulase negative staphylococci, which may be resistant to flucloxacillin.

Prescribing notes

Prior to antibiotic treatment, take at least three sets of blood cultures at 20 minute intervals from separate peripheral venepunctures.
Synergistic dosing of gentamicin is used in endocarditis:
- For guidance on dose, monitoring and duration see Synergistic Dosing of Gentamicin guideline.
- Prescribe synergistic gentamicin on HEPMA - do not prescribe synergistic gentamicin on a gentamicin prescribing, administration and monitoring chart.
- Use the specific synergistic gentamicin monitoring chart for monitoring levels.
Gentamicin must not be administered to patients with myasthenia gravis as it can precipitate a myasthenic crisis.
For recommendations on treatment regimens once the organism and its susceptibilities are known, please refer to the British Society for Antimicrobial Chemotherapy's endocarditis guideline.

Empirical antimicrobial management

For empirical antimicrobial management, use the following links:

Sampling for endocarditis

Condition

Samples to send

Comments

Infective Endocarditis

Infected pacemaker

Infected vascular graft

3 peripheral blood cultures from 3 separate venepunctures, taken minimum 20 minutes apart
Further blood cultures may be taken at clinical team’s discretion

Unless the patient is septic with haemodynamic instability, at least 3 sets of blood cultures should be obtained before empirical antimicrobials are started.

Blood cultures obtained at the same time count as a single set with >2 bottles.

Guideline reviewed	October 2023
Page updated	February 2024