infective endocarditis Flashcards
What parts of the heart can be affected in infective endocarditis
infection of inner layer of heart
endocardium
heart valves:
native
prosthetic
interventricular septum
septal defect
chordae tendinae
intra-cardiac devices
Why is infective endocarditis not a uniform disease
various presentations
possibly dependent on underlying cardiac disease
microorganism involved
presence / absence of complications
underlying patient characteristics
What are the cardiac risk factors that can result in infective endocarditis
Native valve disease
Congenital heart disease tetralogy of fallot Ventral septal defect Patent ductus arteriosus ASD - coarctation of aorta
Rheumatic heart disease
Prosthetic heart valve surgery
cardiac surgery
prior native IE
Cardia hypertrophy
What is the non cardiac risk factors for IE
IVDA
immunocompromised eg elderly/AIDS
diabetes mellitus
AIDS
trauma (burns)
indwelling medial devises
What is the different mode of acquisition in bacteraemia IE
Health care related e.g.
Hospital, health care contact, IV therapy, nursing home
community acquired
IV drug abuse
What is the signs of IE
Murmur
Muscoskeletal pain
splinter haemorrhages vasculitic rash Roth Spots Osler’s nodes Janeway lesions nephritis anemia
What is the symptoms of IE
Fever fatigue malaise Weight loss Headache
What are features of patients with a high Index of suspicion of diagnosis of IE
fever
new murmur
pyrexia of unknown origin
known IE causative organism
prosthetic material
previous IE
congenital heart disease
new conduction disorder
immunocompromised
IV drug abuser
When could signs of IE be absent
elderly
when prior antibiotic treatment has been given before IE was considered
immunocompromised
IE involving less virulent / atypical organisms
What are the investigations for Infective endocarditis
Blood tests: FBC - full blood count (neutrophilia) CRP - C-reactive protein ESR - erythrocyte sedimentation rate Urea & electrolytes
Blood cultures
urinalysis
ECG
CXR
Echo
What does the urea and electrolytes (blood test)indicate for in diagnosis of IE
nephritis
infection
sepsis
What does ECG show in IE
conducting delay - due to abscess sitting on atrial ventricular septa
What does a chest x ray show in infective endocarditis
Heart failure
Pulmonary abscesses
What is the two types of echocardiogram
transthoracic (TTE)
+ transoesophageal (TOE
When would you perform both atransthoracic (TTE)
+ transoesophageal (TOE)
When you have high clinical suspicion of infective endocarditis
When would you perform a TOE
If TTE is positive:
To see complications and assesses
Measure size of vegetation
Poor quality TTE
Prosthetic valve intracardiac device present
If initial TOE negative but still have high clinical suspicion perform again within 7-10days
When would you repeat an ECG in EI
If new complication arrises
To asses ongoing treatment
To asses treatment success on completion
What could be the possible reasons of Infective endocarditis having a negative blood culture
Prior antibiotic treatment
Fastidious organism - only grow with specific nutrients
Intracellular bacteria
Organisms can cause what types of IE
Native valve IE
IVDA IE
Prosthetic valve IE
What is the pathogenesis of IE
damage to the endothelium with invasion and adherence of micro-organism to injured surface, proliferation then breaking of causing thrombotic endocarditis
= a sterile fibrin-platelet vegetation (abnormal mass)
What is the organisms responsible for IE
Staphylococcus aureas - most common
Strepococci (Strep. Viridans)
Pseudomonase
aerguginosa
HACEK organisms
Fungi
Enterococci
How do you test for the intracellular bacteria causing IE
serological testing, cell culture,
gene amplification,
PCR
What is the major factors modified duke criteria for IE
Blood culture of IE positive
- + with 2 separate culture/ persistent
Evidence of endocardial involvement
- ECG
- Valve murmur
What is the minor factors in modified duke criteria
Predisposition
- heart condition/ drug use
fever
vascular/immunologic phenomena
Microbiological evidence
+ blood culture / serological evidence
What is the criteria must be met from modified duke criteria for a definite diagnosis
2 major
1 major + 3 minor
5 minor
What is the treatments for IE
Antibiotics - IV Aminoglycosides
best = bactericidal with shortened duration therapy
Surgery
What does your choice of antibiotic depend upon
Received previous antibiotics
if its either native or prosthetic valve
When valve surgery was performed
local epidemiology
antibiotic resistance
specific culture negative pathogens
What therapy is needed for slow growing dormant microbes
Prolonged antibiotic therapy eg 6 weeks +
+
removal of prosthetic material
What is the antibiotic treatment of native valve IE
IV Gentamicin
1mg/kg 12 hourly
+ IV Amoxycillin
2g 4 hourly
{or vancomycin if if penicillin allergic, severe sepsis or MRSA}
What is the antibiotic treatment for prosthetic valve IE
Gentamicin \+ IV Vancomycin \+ Rifampicin
What is the disadvantages of Gentamicin
nephrotoxic
ototoxic
dose must be measured to actual body weight
What is the monitoring treatment with IE
blood tests daily
ECG every 1-2days
ECHO weekly
What is the complications of IE
heart failure
fistula formation
leaflet perforation
uncontrolled infection
abscess formation
atrioventricular heart block
embolism
prosthetic valve dysfunction /dehiscence
What is the most frequent and severe complication of IE, how is it shown
Heart failure - shown by refractory pulmonary oedema
How do you know the in infection is uncontrolled
Persisting fever and positive blood cultures
What is the cause of an uncontrolled infection
Inadequate antibiotic treatment
resistant organisms
Infected lines
extracardaic site of infection
adverse reaction to antibiotics
How does abscess formation result in
atrioventricular heart block
If abscess in close proximity to base of septum innervates bundle of HIS and prevents conduction in the heart
what is most likely to cause embolism in IE
Previous embolism
Multi-vascular IE
The size and mobility of vegetation
Increasing the antibiotic
What is the most severe IE
prosthetic valve endocarditis
What is the therapy for prosthetic valve endocarditis
removal recommended
and prolonged IV antibiotic course
What is examples of prophylaxis
avoid extensive non-evidence-based use of antibiotics
Maintain good oral dental hygiene
