What is infective endocarditis and where are the most common sites of infection?
Infection of endocardial lining of heart usually involving mitral + aortic valves.
R sided TRICUSPID valve most common in IVDU
Risk factors for infective endocarditis?
Cardiac factors:
- Previous episode (strongest RF)
- Rheumatic valve disease (30%)
- Prosthetic valves
- Congential heart defects
Non-cardiac factors:
- IVDU
- Long-term lines (e.g. ITU)
- Poor dentition/dental surgery
How do you classify IE and what are the differences?
Acute = fulminant illness, pt very unwell
Subacute = Over weeks/months. Less unwell, more signs O/E
What are the common causative organisms for IE?
ACUTE = Staph aureus (MOST COMMON cause of IE), Strep pyogenes (Group A Strep)
SUB-ACUTE = Staph epidermidis, Strep viridans (dental related), HACEK organisms
Causes if culture -ve:
- HACEK
Haemophilus, Acinetobacter, Cardiobacterium, Eikinella, Kingella
Most common causative organism in IVDU?
Staph aureus
Most common causative organism in patients who have had prosthetic valve surgery?
< 2months after surgery:
- Coagulase-negative Staphylococci (CoNS) e.g. Staph epidermidis
- MRSA
> 2 months after surgery: Normal causes i.e. Staph aureus
Signs and Symptoms of IE?
- Fever
- Non-specific Sx: anorexia, weight loss, malaise, fatigue, night sweats, SOB
- New murmur (usually regurg)
EMBOLIC phenomena (vegetations detach from valves):
- Janeway lesions (palms/soles)
- Splinter haemorrhages (nails)
- Can go to brain causing embolic stroke or intracerebral haemorrhage
- Splenomegaly
- Septic abscesses in lungs/brain/spleen/kidney
Immune phenomena (caused by bacterial antigen-antibody complex deposits):
- Oslar’s nodes (fingers/toes)
- Roth spots (eyes)
- Glomerulonephritis -> Haematuria
Investigations for IE?
- 3x blood cultures from 3 different sites: 1 for aerobic, 1 for anaerobic, 1 for fungi.
- Echo
Transthoracic echo = Non-invasive, but lower sensitivity
Trans-oesophageal echo = invasive but higher sensitivity
What is the criteria used for diagnosing IE?
DUKE’S Criteria:
- Pathological criteria +ve
- 2 major
- 1 major + 3 minor
- 5 minor
Pathological criteria = +ve Histology/microbiology obtained at autopsy or cardiac surgery
Major Criteria =
- 2 seperate +ve blood cultures showing typical organisms (Strep viridans, HACEK)
- 2 +ve cultures 12+hrs apart OR 3 or more +ve cultures showing less specific organisms (S. aureus, S. epidermidis)
- +ve for Coxiella burnetii, Bartonella, Chlamydia psittaci
Evidence of endocardial involvement
- Positive Echo findings (oscillating structures, abscess formation, new valvular regurgitation or dehiscence of prosthetic valves)
- NEW valvular regurgitation
Minor Criteria:
- Risk factors (e.g. IVDU, cardiac condition)
- Fever >38
- Embolic phenomena (Splinter haemorrhages, Janeway lesions)
- Immune phenomena (Roth spots, Osler’s nodes, glomerulonephritis)
- +ve Blood cultures not meeting major criteria
Treatment for IE?
Empirical IV Abx as soon as cultures are taken, then change accordingly.
Continue for ~6wks
Initial blind Tx:
- Native valve = Amoxicillin
- Prosthetic valve = Vancomycin + rifampicin + gentamicin
- Penicillin allergy, MRSA or severe sepsis = Vanc + gent
Further Tx:
Native valve + Staph = Flucoxacillin
Prosthetic valve + Staph = Flucox + Rifampicin + Gentamicin
Fully sensitive Strep (e.g. viridans) = BenPen
Less sensitive Strep = BenPen + Gentamicin
What are indications for surgery?
Congestive cardiac failure refractory to medical Tx = indication for emergency valve replacement surgery
Other indications:
- Severe valvular incompetence
- Aortic abscess (often indicated by a lengthening PR interval)
- Infections resistant to Abx OR fungal infections
- Recurrent emboli after Tx
