Infective Endocarditis Flashcards
What is infective endocarditis?
Infection of the endocardium (inner lining of heart, mainly valves)
List 5 cardiac risk factors for infective endocarditis
Acquired valvular disease: rheumatic heart disease, AS, degenerative valve disease
Prosthetic heart valves
Congenital heart defects: VSD, bicuspid aortic valve
Previous endocarditis
Implantation of cardiac device
List 4 non-cardiac risk factors for infective endocarditis
IV drug use
Poor dental hygiene/ Recent dental work
IV catheter
Immunosuppression
List 5 causative organisms of infective endocarditis
Staphylococcus aureus (most common)
Streptococcus Viridans
Coagulase -ve Staph e.g. S. epidermis
Streptococcus bovis
Non-infective
In which patients is staphylococcus aureus IE particularly common?
Acute presentations
IVDU
What is the most common cause of IE in developing countries?
Streptococcus viridians: S. mitis + S. sanguinis
Which organisms are found in the mouth and thus linked to poor dental hygiene or following a dental procedure?
Streptococcus viridians: S. mitis + S. sanguinis
What is the most common cause of IE following prosthetic valve surgery? Why?
Staphylococcus epidermidis
Commonly colonize indwelling lines, usually the result of peri-operative contamination.
After 2 months the spectrum of organisms which cause endocarditis return to normal
Which cause of IE is associated with colorectal cancer?
Streptococcus bovis
Subtype S. gallolyticus is most linked with colorectal cancer
Name 2 non-infective causes of IE
SLE: Libman-Sacks
Malignancy: Marantic endocarditis
List 5 causes of culture negative IE
Prior abx therapy
Coxiella burnetii
Bartonella
Brucella
HACEK: Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella
Describe the pathogenesis of infective endocarditis
- Damaged valvular endothelium; exposure of subendothelial layer
→ adherence of platelets + fibrin
→ sterile vegetation (microthrombus) - Localized infection/ contamination
→ bacteremia
→ bacterial colonization of vegetation
→ formation of fibrin clots encasing the vegetation
→ valve destruction with loss of function (valve regurgitation)
Describe valve involvement in IE
Mitral > Aortic > Tricuspid > Pulmonary
Which valve is most commonly affected in IVDU with IE?
Tricuspid
List 3 clinical consequences of bacterial colonisation of vegetation in IE
Bacterial vegetation→ bacterial thromboemboli→ vessel occlusion→ Infarctions
Emboli can lead to metastatic infections of other organs.
Formation of immune complexes + antibodies against tissue antigens → glomerulonephritis, Osler nodes
List 3 symptoms of infective endocarditis
Fever + chills (most common)
FLAWS
Arthralgias + myalgias
How may sub-acute IE differ in presentation to acute IE?
Sub-acute: nonspecific flu-like Sx
Acute: signs of acute sepsis.
List 3 cardiac manifestations of IE
New murmur
HF: due to valve insufficiency
Arrhythmias: due to perivalvular abscess causing conduction delay
Depending on the valve affected, which murmur may be heard in IE
TR: pansystolic, loudest at LSB
AR: Early diastolic loudest at 3rd ICS, LSB
MR: Pansystolic loudest at apex
List 4 extra-cardiac manifestations of IE
Peripheral embolic + immunologic phenomena
Emboli to intra-abdominal organs
Neurological manifestations
Pulmonary manifestations
List 4 peripheral embolic and immunologic phenomena in IE
Petechiae, esp. splinter haemorrhages
Janeway lesions (non-tender macules on palms + soles)
Osler nodes (painful nodules on pads of fingers + toes)
Roth spots (retinal haemorrhages)
Give 2 examples of where IE may emboli to intra-abdominal organs
AKI: haematuria + anuria
Splenomegaly + LUQ pain
What may cause neurological manifestations in IE?
Septic embolic stroke
Hemorrhage
Meningitis
Encephalitis
Abscess
What do pulmonary manifestations of IE result from? What does this cause?
Septic emboli from tricuspid involvement
Signs of PE e.g. dyspnoea
Signs of pulmonary infection
What criteria is used to diagnose infective endocarditis?
Modified Duke criteria
What defines the Modified Duke Criteria?
Pathological criteria positive
OR
2 major criteria
OR
1 major + 3 minor criteria
OR
5 minor criteria
What constitutes positive pathological criteria for IE?
+ve histology or microbiology of pathological material obtained at autopsy or cardiac surgery (valve tissue, vegetations, embolic fragments or intracardiac abscess content)
What are the majors in the modified duke criteria?
+ve blood cultures
Evidence of endocardial involvement
What constitutes positive blood cultures in the major criteria for IE?
2 +ve blood cultures with typical organisms for IE
OR
Persistent bacteraemia from 2 blood cultures taken > 12h apart or >,3 +ve blood cultures
OR
+ve serology for Coxiella burnetii, Bartonella species or Chlamydia psittaci
What constitutes evidence of endocardial involvement in IE?
+ve echo: oscillating structures, abscess formation, new valvular regurg or dehiscence of prosthetic valves
OR
New valvular regurgitation
What are the minor criteria for IE?
Predisposing heart condition or IVDU
Fever > 38ºC
Vascular phenomena: major arterial emboli, splenomegaly, splinter haemorrhages, Janeway lesions
Immunological phenomena: glomerulonephritis, Osler’s nodes, Roth spots
Microbiological evidence:
+ve blood cultures not meeting major criteria or serological evidence of active infection with organism consistent with IE.
Describe investigations for infective endocarditis
3 separate sets of blood cultures from 3 different sites
ECG
TTE (possible TOE if inconclusive)
Bloods: FBC, CRP, U+Es, LFTs
Urinalysis
Why is urinalysis performed in IE? What may be found?
Septic emboli are common complication
Haematuria + nephritic sediment
What investigation would be performed in patients with S. gallolyticus?
Colonoscopy to r/o colorectal cancer
What investigation should be performed in all patients with IE once stable and receiving therapy?
Dental assessment
What may be seen on ECG in infective endocarditis?
Progression of infection can lead conduction abnormalities
Prolonged PR interval, non-specific ST/T wave abnormalities, AV block
What is seen on echocardiography in IE?
Valvular vegetations
New valvular regurgitation
+/- Abscess (e.g., perivalvular abscess)
List 4 poor prognostic factors in IE
S. aureus infection
Prosthetic valve (esp. ‘early’, acquired during surgery)
Culture -ve endocarditis
Low complement levels
Describe the mortality of IE according to organism
Staphylococci - 30%
Bowel organisms - 15%
Streptococci - 5%
What is the initial blind therapy for suspected infective endocarditis in patients with a native valve?
Amoxicillin
+/- low dose Gentamicin
If pen allergy, MRSA or severe infection: Vancomycin + low dose Gentamicin
What is the initial blind therapy for suspected infective endocarditis in patients with a prosthetic valve?
Vancomycin + Rifampicin + low-dose Gentamicin
Tx of native valve endocarditis caused by staphylococci
Flucloxacillin
If pen allergy or MRSA: Vancomycin + Rifampicin
Tx of prosthetic valve endocarditis caused by staphylococci
Flucloxacillin + Rifampicin + low-dose Gentamicin
If pen allergy or MRSA: Vancomycin + Rifampicin + low-dose Gentamicin
Tx of endocarditis caused by fully-sensitive streptococci (e.g. viridans)
Benzylpenicillin
If pen allergy: Vancomycin + low-dose Gentamicin
Tx of endocarditis caused by less sensitive streptococci
Benzylpenicillin + low-dose Gentamicin
If pen allergy: Vancomycin + low-dose Gentamicin
When may surgical treatment be needed in infective endocarditis?
Severe valvular incompetence
Aortic abscess (often indicated by a lengthening PR interval)
Infections resistant to abx /fungal infections
Cardiac failure refractory to standard medical Tx
Recurrent emboli after abx therapy
List 4 complications of infective endocarditis
Acute HF
Systemic embolisation inc. Stroke
AKI
Valvlar dehiscence, rupture or fistula
What is the prognosis in infective endocarditis?
FATAL if untreated
15-30% mortality even WITH treatment
Do dental, upper and lower GI tract,
GU tract, O+G or resp procedures require IE prophylaxis?
NO
