MICRO: CVS Infections Flashcards
infective endocarditis
- aetiology
- what is it
- most commonly: S. aureus and streptococcus but can also be fungal
- infection of heart valves/inner lining of heart
pathophys of endocarditis
- endothelial cell damage from another condition triggers clotting cascade = non-bacterial thrombotic endocarditis (NBTE)
- if there is bacteria in the blood it will adhere to the clots and colonise
how does transient bacteraemia occur?
- breach of mucous membrane
- e.g. dental procedures (S. viridans), tooth brushing, GIT procedures
diseases which can predispose to infective endocarditis
- rheumatic heart disease (autoimmune condition triggered by previous GABHS pharyngitis infection)
- congenital heart disease (embryological defects)
- degenerative heart disease e.g. mitral valve prolapse w/ regurg (mitral valve bulges back into L atrium instead of closing properly)
types of infective endocarditis
- native valve endocarditis: host’s own valves, usually w/ pre-existing condition (acute vs subacute)
- prosthetic valve endocarditis: early vs late
- IV drug-associated endocarditis
- nosocomial endocarditis e.g. catheters
2 types of native valve endocarditis:
- bacteria involved
- speed of onset
- virulence
- subacute (VIRIDANS, ENTEROCOCCUS): slow onset, low virulence (own flora)
- acute (S AUREUS): quick onset, high virulence
rheumatic fever/heart disease
- how does it occur
- Sx
- occurs 2-4 wks after GABHS pharyngitis - antibodies against S. pyogenes cross-react w/ heart and tissues
- Sx: subcutaneous nodules, polyarthritis, chorea (rare)
2 types of prosthetic valve endocarditis
- bacteria involved
- how is it acquired
- when is it acquired
- early (S. AUREUS - COAGULASE -VE): hospital acquired from inoculation, <60 days post valve replacement surgery
- late (S. AUREUS): community acquired, >60 days after valve surgery
endocarditis associated w/ IV drug use
- which bacteria is involved
- which valves does it commonly affect
- S. aureus
- most commonly affects tricuspid valve followed by aortic valve
- most Pts have no history of heart disease
signs and Sx of infective endocarditis
- Sx: fever, sweats, chills, anorexia, malaise, LOW
- signs: anaemia, splenomegaly, clubbed fingers, heart murmur, Janeway lesions, Osler’s nodes, splinter haemorrhages
how to Dx infective endocarditis
- blood cultures (MOST IMPORTANT): 3 blood cultures over 24 hrs taken from diff veins, BEFORE ANTIBIOTICS
- non-specific: elevated WBC, elevated CRP, elevated erythrocyte sedimentation rate
reasons for negative blood culture for infective endocarditis
- Pt may have recently been on antibiotics
- organisms are fastidious (need specific conditions) or difficult to cultivate
Duke criteria for infective endocarditis
- evidence of endocardial involvement via echocardiogram (most important)
- +ve blood culture
Tx for infective endocarditis
- parenteral bactericidal antibiotics after blood culture
- eradication of biofilms (higher concentration and longer duration of antibiotics)
causes of myocarditis
- infectious: mainly viral e.g. coxsackie, ECHO virus
- non-infectious: toxin, cocaine, anti-cancer drugs
signs and symptoms of myocarditis
- asymptomatic
- flu-like illness w/ chest pain
- arrythmia
- signs of CHF
investigations to diagnose myocarditis
- echocardiogram
- ECG
- CXR
- need biopsy to confirm
myocarditis Tx
- most are self-limiting
- cardiac monitoring of arrhythmias
- antimicrobials
pericarditis pathogen and transmission
- most commonly viral (enterovirus e.g. coxsackie and echovirus)
- blood-borne, inoculation during surgery or trauma
signs and Sx of pericarditis
- signs: friction rub, cardiac tamponade, decreased heart sounds
- Sx: fever, dyspnoea, chest pain, cough
how does the pain of pericarditis feel and how is it relieved?
- stabbing/burning pain
- relieved by leaning forward
how to Dx pericarditis
- ECG
- echocardiogram
- blood culture from pericardial fluid
Tx for pericarditis
- viral: bed rest
- may need emergency pericardiocentesis or systemic antibiotics if severe
how to classify a fever of unknown origin (FUO)
- temp > 38.3˚C for more than 3 weeks despite 1 week of intensive evaluation
