Infective Endocarditis Flashcards
define bacteraemia
presence of bacteria in the bloodstream
life threatening - patients develops septic shock and dies
risk factors for implantable cardiac electronic devices
pre procedure prophylaxis complexity of procedure temporary pacer use type of device number of revisions/re-interventions fever within 24 hours heart or renal failure haematoma post procedure
describe implantable cardiac electronic devices (ICED) and infection
generator pocket infection; localised cellulitis, pain, swelling, discharge, wound breakdown infective endocarditis (IE) or ICED lead infection (ICED-LI) co-exist
symptoms/signs of infected ICED
non-specific signs of systemic infection - fevers, chills, night sweats, malaise, anorexia
fewer than 10% of patients present with septic shock
secondary foci - spinal or pulmonary infeciton
tests for infected ICED
patient has fever and new murmur - suspected endocarditis until proven otherwise Duke criteria - Confirm diagnosis if the patient is experiencing 2 majors or 1 major and 3 minors or all 5 minor criteria. blood culture (prior to beginning antibiotics)
how should blood tests be taken for suspected ICED infeciton
3 sets of bloods from peripheral sites with >6 hours between them
should be taken before antibiotics
if negative - consider serology for atypical organism
treatment of generator pocket infection with evidence of sepsis
blood culture x2
empirical IV antimicrobial therapy within 1 hour
urgent echocardiography
prompt removal of entire system and temporary pacing if needed
blood culture;
positive - modify antimicrobial therapy
negative - echocardiographic evidence of lead or tricuspid valve vegetation or tricuspid regurgitation;
yes - manage for ICED-IE/ICED-LI
no - complete 10-14 antimicrobial therapy after system removal
treatment of generator pocket infection with no evidence of sepsis
blood culture x3
echocardiography
arrange removal of entire system and temporary pacing if needed
empirical oral/IV antimicrobial therapy as clinically appropriate
blood culture;
positive - modify antimicrobial therapy
negative - echocardiographic evidence of lead or tricuspid valve vegetation or tricuspid regurgitation;
yes - manage for ICED-IE/ICED-LI
no - complete 10-14 antimicrobial therapy after system removal
describe infective endocarditis
infection of the endothelium of the heart valves life threatening (often diagnosed late) can be acute or subacute
epidemiology infective endocarditis
uncommon - 1:1000
increases with age
hospital cases increasing - due to staphylococcus aureus
risk factors for infective endocarditis
heart valve abnormality;
calcification/sclerosis in elderly
congenital heart disease
post-rheumatic fever
prosthetic heart valve
IV drug users
intravascular lines
pathophysiology of endocarditis
heart valve is damaged - usually left side (mitral and aortic valves)
turbulent blood flow over roughened endothelium (producing murmur)
platelets/fibrin deposited
bacteraemia (may be very transient) e.g. from dental treatment
organisms settle in fibrin/platelet thrombi becoming a microbial vegetation
infected vegetations are friable and break off, becoming lodged in the next capillary bed they encounter - causing abscesses or haemorrhage (can be fatal)
common organisms causing endocarditis
in order of most frequent; gram postive; staphylococcus aureus viridans group streptococci enterococcus sp staphylococcus epidermidis
uncommon organisms causing endocarditis
atypical;
bartonella, coxiella burnetii (Q-fever), chlamydia, legionella, mycoplasma, brucella
gram negative - HACEK;
haemophilus spp, aggregatibacter spp, cardiobacterium, eikenella sp, kingella sp
non HACEK
fungi
Duke - major criteria for endocarditis
Positive blood cultures - typical organism in 2 separate cultures OR persistently positive blood cultures (3 >12 hours apart)
Endocardium involved;
Echocardiography - Strictures (narrowing), Unusual blood flow, Vegetation, Abscesses
New valvular regurgitation
duke - minor criteria for endocarditis
Predisposition (IV drug abuse, cardiac lesion)
Fever >38°C
Vascular/immunological signs
Positive blood culture that does not meet major criteria
Positive echocardiogram that does not meet major criteria
what is the coagulase test
distinguishes between staphylococcus aureus and coagulase-negative staph
describe staphylococcus epidermis
most common coagulase negative staphylococcus skin contaminant (another skin contaminant includes corynebacterium sp) can infect prosthetic material - intravascular line infections, prosthetic heart valves/joints
symptoms of acute endocarditis
overwhelming sepsis and cardiac failure
usually due to aggressive (virulent) organisms e.g. staphylococcus aureus
symptoms of subacute endocarditis
fever malaise weight loss tiredness breathlessness
signs of subacute endocarditis
new or changing heart murmur finger clubbing splinter haemorrhages splenomegaly roth spots, janeway lesions, osler nodes microscopic haematuria
prosthetic valve endocarditis
early (within 60 days) - usually infected at time of valve insertion and usually due to staphylococcus epidermidis or staphylococcus aureus
late - up to many years after valve insertion, due to co-incidental bacteraemia. Wide range of possible organisms
endocarditis in people who inject drugs
right sided endocarditis
most likely staphylococcus aureus
suspect staphylococcus aureus plus septic PE
treatment for native valve endocarditis
amoxicillin
gentamicin IV
