Infective Endocarditis Flashcards
Infective Endocarditis: What is it?
Infective endocarditis= infection of theendothelium(the inner surface) of the heart. It most commonly affects theheart valves. It can beacute,subacuteorchronic, depending on how rapidly and acutely the symptoms present and the causative organism.
Infective Endocarditis: Risk Factors
- IV drug use
- History of infective endocarditis
- Immunocompromised (e.g., cancer, HIV or immunosuppressive medications)
- Chronic kidney disease (particularly on dialysis)
- Structural heart pathology (see below)
- Valvular heart disease
- Congenital heart disease
- Hypertrophic cardiomyopathy
- Prosthetic heart valves
- Implantable cardiac devices (e.g., pacemakers)
Infective Endocarditis: Aetiology
gram positive cocci.
- - Staphylococcus aureus (MOST COMMON CAUSE)
- Streptococcus(notably theviridans groupof streptococci, incl. Streptococcus mitis and Streptococcus sanguinis) - linked with poor dental hygiene or following a dental procedure
- Staphylococcus epidermidis - linked with prosthetic valve surgery for up to 2 months
- Streptococcus bovis -
associated with colorectal cancer. Should prompt urgent investigation as the bacteria may have been released into the bloodstream due to a colon tract breakdown. - Enterococcus(e.g.,Enterococcus faecalis)
- Rarer causes include Pseudomonas, HACEK organisms and fungi, systemic lupus erythematosus (Libman-Sacks)
Infective Endocarditis: Symptoms
- fever, fatigue, myalgia, malaise
- night sweats
- anorexia
Infective Endocarditis: Examination signs
- Newor “changing”heart murmur
- Splinter haemorrhages(thin red-brown lines along the fingernails)
- Petechiae(small non-blanching red/brown spots) on the trunk, limbs, oral mucosa or conjunctiva
- Janeway lesions(painless red flat macules on the palms of the hands and soles of the feet)
- Osler’s nodes(tender red/purple nodules on the pads of the fingers and toes)
- Roth spots(haemorrhages on the retina seen during fundoscopy)
- Splenomegaly(in longstanding disease)
- Finger clubbing(in longstanding disease)
Infective Endocarditis: Diagnosis (Duke Criteria)
A diagnosis requires either:
- One majorplusthree minorcriteria
- Five minorcriteria
Major criteriaare:
- Persistently positiveblood cultures(typical bacteria on multiple cultures)
- Specificimaging findings(e.g., a vegetation seen on the echocardiogram)
Minor criteriaare:
- Predisposition(e.g., IV drug use or heart valve pathology)
- Feverabove 38°C
- Vascular phenomena(e.g., splenic infarction, intracranial haemorrhage and Janeway lesions)
- Immunological phenomena(e.g., Osler’s nodes, Roth spots and glomerulonephritis)
- Microbiological phenomena(e.g., positive cultures not qualifying as a major criterion)
Infective Endocarditis: Investigations
Blood culturesare essentialbeforestarting antibiotics. Three blood culture samples are recommended, usually separated by at least 6 hours and taken from different sites. The gap between repeated sets may have to be shorter if antibiotics are required more urgently (e.g., sepsis).
Echocardiographyis the usual imaging investigation.Transoesophageal echocardiography(TOE) is more sensitive and specific thantransthoracic echocardiography.Vegetations(an abnormal mass or collection) may be seen on the valves.
most commonly affected by infective endocarditis are (in decreasing order of frequency): mitral valve, aortic valve, combined mitral and aortic valve, tricuspid valve (most common in IV drug users), pulmonary valve (rare).
Special imaging investigations may be used in patients withprosthetic heart valves, where it can be more challenging to determine whether an infection is present in the prosthesis:
- 18F-FDG PET/CT
- SPECT-CT
Infective Endocarditis: Management
Patients require admission and are managed by the relevant specialist team (e.g., the infective endocarditis or infectious diseases team).
Intravenous broad-spectrum antibiotics(e.g.,amoxicillinand optionalgentamicin) are the mainstay of treatment. The choice of antibiotic may be more specific once the causative organism is identified on cultures. Antibiotics are typically continued for at least:
- 4 weeks for with native heart valves
- 6 weeks for patients with prosthetic heart valves
Surgerymay be required for:
- Heart failure relating to valve pathology
- Large vegetations or abscesses
- Infections not responding to antibiotics
CHECK PASSMED
Infective Endocarditis: Prophalylaxis
For those at high-risk, antibiotics are considered for dental and non-dental procedures and are advised to take good care of their oral health. NO ANTIBIOTICS NEEDED
Infective Endocarditis: Complications
Infective endocarditis has ahigh mortalityrate. Key complications include:
- Heart valve damage, causing regurgitation
- Heart failure
- Infective and non-infective emboli (causing abscesses, strokes and splenic infarction)
- Glomerulonephritis, causing renal impairment
