Infective endocarditis Flashcards
What is infective endocarditis?
Infection of endocardium, affecting the:
- Heart valves
- Inteventricular septum
- chordae tendinae
- intra-cardiac devices
Describe the epidemiology of IE
Older patients Degenerative aortic stenosis Rheumatic heart disease Invasive procedures Intracardiac devices Valve disease Prosthetic valves CHD IV drug abuse (usually affects R side) Immunocompromised patients
Name some cardiac risk factors for IE
MVP VSD AS RHD Prosthetic valves Cardiac surgery for native IE Prior native IE Surgery for prosthetic IE
Name some non-cardiac risk factors for IE
IV drug use Indwelling medical devices DM AIDS Chronic skin infections or burns Genitourinary infections Pregnancy/abortion/delivery Alcoholic cirrhosis GI lesions Solid organ transplant Homeless, lice Pneumonia and meningitis Infected farm animals Dog/cat exposure
Describe the pathophysiology of IE
Damage to epithelium:
- Nonbacterial thrombotic endocarditis, sterile vegetation
- Mechanical disruption of valve endo.
Bacterial colonisation
What can cause bacteraemia?
Extracardiac infections
Invasive procedures
Gingival disease
Activities of daily living e.g. brushing teeth
What organism is most associated with acute onset IE?
Staph Aureus
What organism is most associated with sub-acute onset IE?
Streptococci
Describe some modes of acquisition of IE
Health care related - nosocomial/idiopathic (hospital) - non-nosocomial (home based care) Community acquired IVDA
State some symptoms of IE
Fever Fatigue Malaise weight loss headache Musculoskeletal pain Altered mentation (mental activity) Murmur Immune complex deposition e.g. splinter haemorrhages, vasculitic rash, Roth spots, Oslers nodes, Janeway lesions Nephritis Signs of HF
Describe vasculitis rash
Diffuse, non-blanching red/purple (petechial) spots, purpuric
What does purpuric mean?
Rash caused by internal bleeding from small vessels
Describe Roth’s spots
Retinal haemorrhages, spots with a white pale centre at the back of the eye due to coagulated fibrosis
Describe Oslers nodes
Deep red spots, painful, raised, tend to be on finger pulps but can be on the palms or soles of the feet
Describe Janeway lesions
Flat, echymotic (like bruises) on palms or soles of feet, non-tender
What clinical sign is pathognomonic for IE?
Janeway lesions
When might some clinical signs be absent in patients?
Immunocompromised
Elderly
After antibiotic treatment
IE evolving less virulent/atypical organism
When should you be very suspicious of IE?
New murmur Pyrexia of unknown origin Known IE causative organism Prosthetic material Previous IE CHD New conduction disorder Immunocompromised IVDA
What investigations would be used for IE?
Full blood count e.g. CRP, ESR, U+Es Urinalysis - blood = nephritis ECG CXR ECG - TTE and TOE Blood cultures
How should blood cultures be taken?
3 sets taken 6 hours apart from different sites of the body
If in septic shock, this is accelerated to only 2 sets taken an hour apart
Describe ECG taking when investigating IE
TTE first only
- if positive straight to TOE
- if negative no TOE unless clinical suspicion is high, and then repeat after 7/10 days
Why is TOE taken?
When suspicion is high, to find:
- complications
- abscesses
- measure size of vegetation
When should ECG (TTE/TOE) be repeated?
If suspicion is still high
New complication e.g. murmur, fever, embolism, HF
To assess treatment efficacy
What % of IE cultures show positive blood cultures?
85%
Why might IE blood cultures be negative?
Prior antibiotic therapy
Fastidious organisms
Intracellular organisms
What 3 types of microorganism are most common in IE?
Streptococci
Enterococci
Staphylococcus
Describe the pathology of IE
A mass of fibrin, platelets and infectious organisms forms vegetations along the edges of the valves. Virulent organisms destroy the valves, producing regurgitation and worsening heart failure
What type of organism is most likely to be found in disease of a native valve?
Streptococci
What type of organism is most likely to be found in disease of a prosthetic valve?
Staphylococci
Name some Staphylococci species linked to IE
S. Aureus
S. Epidermidis
Name some Streptococci species linked to IE
S.viridans
S.anginosus
S. bovis
Name some Enterococci species linked to IE
E.faecalis
E.faecium
E.durans
Name some fastidious organism species linked to IE
Brucella
Fungi
Nutritionally variant streptococci
Fastidious gram -ve bacilli/HACEK group
Name some organisms that belong to the HACEK group
Haemophilus spp.
Cardiobacterium spp.
Name some intracellular bacteria spp. linked to IE
Coxiella burnetii
Bartonella
Chlamydia spp.
How can you test for intracellular bacteria?
Serological testing
Cell culture
Gene amplification
PCR
What criteria is used for IE diagnosis?
Modified duke criteria
What criteria is needed for a definite IE diagnosis
2 major
1 major + 3 minor
5 minor
What criteria is needed for possible IE diagnosis
1 major
3 minor
What counts as a major criteria for IE?
Positive blood cultures
Evidence of endocardial involvement
What counts as mine criteria for IE?
Fever
Predisposition
Vascular phenomena
Immunological phenomena
How are all drugs for IE given?
IV for 2 weeks, then oral for another 2-4 weeks
What drug is used for MSSA - flucloxacillin or vancomycin?
Flucloxacillin
What drug is used for MRSA - flucloxacillin or vancomycin?
Vancomycin
Why is gentamicin only used in severe cases?
Nephrotoxic
Ototoxic
How do you dose gentamicin?
Dose to body size unless obese (then use ideal body size)
How do we prevent toxicity of gentamicin?
Take serum levels after 4th dose
Daily FBC, U+Es and CRP
ECG every 1-2 days
Weekly echocardiogram
What should the trough level of gentamicin be (pre dose)?
<1mg/L
What should the peak level of gentamicin be?
1hr post dose
3-5mg/L
When are fungal infections in IE common?
Immunocompromised
Prosthetic valves IE
IVDA
What are common fungal causative agents of IE?
Aspergillis spp
Candida spp
State some complications of IE that indicate need for surgery
Heart failure Fistula formation Leaflet perforation or obstruction Uncontrolled infection Abscess formation AV heart block/damage to conduction system Embolism Enlarging vegetation Prosthetic valve dysfunction/dehiscence
What is the Gerbode defect?
Shunt from fistula between left ventricle and right atrium
What cardiac conditions are at highest risk of IE?
Acquired valvular disease
Structural CHD
Hypertrophic cardiomyopathy
Previous IE
When should prophylaxis be offered?
Person at risk e.g. IVDA
Undergoing GI/GU/site of suspected infection procedure
What % of IE cases are caused by health care associations?
30%
When is prophylaxis not given?
Tattoo/piercing Dental procedures Urological/gynaecological/childbirth ENT procedures Bronchoscopy
