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CR - Cardiovascular Infections (i) endocarditis (intro (easily missed…
CR - Cardiovascular Infections (i) endocarditis
intro
Tx = v long (4-6 wks), so use narrowest possible antibiotics (targeted tx)
uncommon (<0.1% of hosp admissions)
potentially fatal (mortality = 100% when untxed)
easily missed
high index of suspicion needed
non-specific clinical features
in differential for PUO
risk factor in resource-poor countries = rheumatic fever (txable, caused by GAS)
risk factor in well-resourced countries = IV/prosthetic devices in situ for a long time
sometimes preventable with prophylactic antibiotics
increasing incidence due to more IVDUs + prosthetic valve surgeries
increasing mean age (50) due to ageing pop + decline in rheumatic fever
majority of patients have a recognised lesion (e.g. aortic stenosis)
Categories
native valve
often community-acquired (no healthcare contact)
sometimes nosocomial/healthcare-related as a result of invasive procedures
usually S aureus, viridans strep, enterococci
prosthetic valve
mostly coag -ve staph (30-35%) + S aureus (20-25%) when early-onset (within 60 days of getting new valve)
others: enterococci, viridans strep (mutans = commonest late-onset cause), HACEK, fungal, polymicrobial
IVDU
often right sided (tricuspid valve)
deposits in lung
can be classified by organism - strep, staph, fungal etc
subacute (usually coag -ve staph)
acute (S aureus)
risk factors
heart lesion
prosthetic valve
previous endocarditis
patent ductus arteriosus
aortic/mitral regurg/stenosis
Procedure
tonsillectomy
surgery of GIT, CUT or upper resp tract
indwelling devices
dental (e.g. tooth extraction)
IVDU
animal exposure/pets
Pathogenesis
usually a defect/lesion causes turbulent blood flow
BSI following a procedure
platelets + fibrin = nidus (focus of infection - pathogen multiplies here)
vegetation develops
infective, immune + embolic complications
valve rupture (tissue damage)
immune activation (vasculitis, acute glomerulonephritis)
BSI (fever, rigors)
most common on left
septic emboli in systemic circulation
stroke
ischaemic bowel (obstructed mesenteric art)
splinter haemorrhages (tiny emboli in capills)
gangrene
factors determining if a vegetation forms
type of organism
microbial load (depends on host immunocompetancy - effectiveness of defence mechanisms)
site/type of heart defect
Aetiology
staph
aureus (20%)
coag -ve (15%)
increasing, now over 40% of cases
strep
decreasing, now under 40% of cases
viridans (alpha-haemolytic) = 20-25%
oralis
mutans
mitis
bovis (if BSI do colonoscopy - CR carcinoma)
enterococci (e.g. faecalis) = 1% (esp in elderly)
other = 5%
others = 4%
don't culture - Dx via serology/PCR
chlamydia
Q fever
brucella
legionella
mycoplasma
bartonella
v uncommon
HACEK = 2%
fastidious - require prolonged incubation
Haemophilus, Aggregatibacter (previously Actinobacillus), Cardiobacterium hominis, Eikenella, Kingella
cause culture -ve endocarditis
fungi = 1-2%
no organism = 5-10%
clinical features
fever
often low grade
+/- chills, rigors, night sweats
murmer
in 85%
new or changing (i.e. patient may already have one)
+/- other cardiac signs (depends on veg size)
non-specific: malasia, fatigue, weightloss, arthralgia, myalgia
embolic phenomena
art emboli (pale leg)
stroke
pul infarcts (esp IVDUs)
Janeway lesions
immunological phenomena
now rarely seen
roth spots (retinal haemorrhages)
Osler's nodes