Infective Endocarditis Flashcards
Risk factors for bacterial endocarditis
-Prosthetic valves
=mitral > aortic > tricuspid > pulmonary
-Cyanotic congenital heart disease
-IV drug use
-Previous infective endocarditis
=TURBULENT FLOW, fibrin deposit, bacterial infection to biofilm
Organisms that cause endocarditis
-Staphylococci 40%
-Streptococci 30%
-Enterococci 11%
-Fungi 2%
-Other 13%
-Polymicrobial 2%
-Culture negative 10%
Pathophysiology of bacterial endocarditis
-Underlying risk factor
-Turbulent flow
-Fibrin deposition
-Biofilm growth
Symptoms of bacterial endocarditis
-Malaise
-Fatigue
-Fever 96% of cases!!!
-Sweating (night sweats)
-Anorexia
-Weight loss (malignancy is often suspected)
-Arthralgia
-Muscle pains
-Abdominal pain (splenic/renal infarction due to septic emboli)
-Intravenous drug abuser – be aware of risk of tricuspid valve endocarditis (Right heart)
Clinical signs of bacterial endocarditis
- Pyrexia
- Heart murmur
- Urinalysis - red cells, proteinuria
- Splenomegaly
- Finger clubbing (rare)
- Nail bed infarcts
- Osler’s nodes (tender lesions in fingers and toes, pustules)
- Splinter haemorrhages
- Petecheal rash (shins, soles of feet, hands)
- Janeway lesions (non-tender lesions)
- Roth spots (retinal-boat shaped lesions)
Investigations of bacterial endocarditis
- Routine bloods- U&E, glucose, FBC, LFT, CRP
- Blood cultures: a minimum of 3 separate sets, avoid contamination, try different sites
- CXR
- ECG
- Transthoracic Echocardiography
- CT scan, splenomegaly, splenic infarcts
- Sometimes specific microbial tests, for suspected Q fever (animal contact)
What criteria is used for infective endocarditis?
Modified Duke Criteria
-Major: positive blood culture for infective endocarditis, evidence of endocardial involvement (echocardiogram)
-Minor: predisposition (cardiac abnormality/ IVDU), fever, vascular/ immunological/ microbiological phenomena, PCR, echocardiographic findings
When to suspect IE
- A febrile illness associated with a new or pre-existing heart murmur
- A febrile illness and no other clinically obvious site of infection
- A febrile illness associated with any of:
=Predisposition to BE and recent intervention (e.g. upper GI endoscopy) and bacteraemia,
=Evidence of congestive heart failure,
=New ECG conduction disturbance,
=Vascular or immunological phenomena: embolic event, Roth spots, splinter haemorrhages, Janeway lesions, Osler’s nodes,
=A new stroke
=Peripheral abscesses (renal, splenic, cerebral, vertebral) of unknown cause - Unexplained, protracted history of sweats, weight loss, anorexia or malaise
- Any new unexplained embolic event (e.g. cerebral or limb ischaemia)
6.Unexplained, persistently positive blood cultures - Intravascular catheter-related bloodstream infection with persistently positive blood cultures
- Unexplained Febrile/infective illness in an intravenous drug user – look for tricuspid valve endocarditis with echo
Microbiology of bacterial endocarditis
- Staphylococcus aureus is commonest cause of endocarditis in the developed world.
- Streptococcus species are the second commonest cause
- Enterococcus species are the third
- Coagulase negative staphylococcus are the fourth ( usually prosthetic valve)
- 30% of cases have negative blood cultures negative.
=Commonest reason is recent antibiotics.
=Take a travel and animal exposure history as Q fever (Coxiella burnetti) is a cause. It is diagnosed by serology
Antibiotics for staph aureus native valve
-Flucloxacillin 2g 4-6 times a day for 4 weeks
Antibiotics for MRSA prosthetic valve
-Vancomycin 1g twice a day for six weeks
-Plus Rifampicin 600mg twice a day for six weeks
-Plus Gentamicin 1mg/kg twice a day for two weeks
Antibiotics for streptococcal endocarditis
-Benzylpenicillin 1.2 to 2.4g six times a day for 2 to six weeks sometimes with gentamicin 1mg/kg twice a day or
-Ceftriaxone 2g once a day instead of benzylpenicillin
Antibiotics for enterococcus endocarditis
-Amoxicillin 2g six times a day plus either gentamicin 1mg/kg twice a day or ceftriaxone 2g twice day for 4-6 weeks
Complications and monitoring of bacterial endocarditis
-Stroke (left side)
-Heart failure (valve insufficiency, aortic)
-Heart block
-Venous line infection
-Mycotic aneurysm
-Antibiotic toxicity
=Deafness
=Tinnitus
=Renal dysfunction
-CRP two to three times a week
-U&E, FBC
-Plasma antibiotic levels
-ECG
-Echo
Factors to consider in surgical treatment of bacterial endocarditis
-Monitoring response to treatment
-Signs indicating need for surgery- 1cm vegetation, valve involvement
-Timing of surgery
-Outcomes of surgery
