Infective endocarditis & other cardiac infections Flashcards
what is a blood culture normally?
sterile
what is a potentially life-threatening situation that can occur in the bloodstream?
i.e. what is meant by bacteraemia?
what happens if this life threatening situation is NOT treated promptly?
- presence of bacteria in bloodstream (bacteraemia or septicaemia)
= presence of bacteria in the bloodstream
= patient may develop septic shock and die
what 3 question should you ask yourself if there is a positive culture?
1) What is the usual HABITAT of the organism?
2) what DISEASES is this organism associated with?
3) what is the optimum ANTIMICROBIAL management required?
what is infective endocarditis?
= infection of endothelium of the heart valves which is life threatening
what are the 2 types infective endocarditis can be?
1) acute
2) sub-acute
what are 4 predisposing factors for infective endocarditis?
1) heart valve abnormality
2) prosthetic heart valve
3) Intra-venous drug users
4) intra-vascular lines
what are 3 possible heart valve abnormalities that could act as predisposing factors for infective endocarditis?
1) calcification/sclerosis in elderly
2) congenital heart disease
3) post rheumatic fever
what pathological change happens to the heart valves in infective endocarditis?
= heart valves are damaged
what happens to blood flow in infective endocarditis?
= turbulent blood flow over roughed endothelium
what is pathologically deposited in infective endocarditis?
= platelets/fibrin is deposited
what pathological thing might happen in the blood stream in infective endocarditis?
= bacteraemia (may be very transient)
e.g. from dental treatment
where does the bacteria organisms in infective endocarditis settle and thus what do they become?
- organism settle in fibrin/platelet thrombi
BECOMING
= a microbial vegetation
what can happen to the infected vegetations when they become friable and break off in infective endocarditis?
= they break off
= becoming lodged in next capillary bed they encounter
= causing abscesses or haemorrhage
- may be fatal
what side of the heart is usually affected?
and thus what 2 valves are most usually affected?
= left side of heart
= mitral and aortic valves
what are the 4 organisms causing endocarditis native valve?
from most common to least
1) staphylococcus aureus
2) viridan’s streptococci
3) enterococcus sp
4) staph epidermidis
what are 3 branches of unusual organisms causing endocarditis?
1) atypical organisms
2) gram-negatives
3) fungi
give examples of atypical organisms that are unusual organisms in causing endocarditis?
- bartonella
- coxiella burnetii
- chlamydia
- legionella
- mycoplasma
- brucella
give examples of gram negative organisms that are unusual organisms in causing endocarditis?
1) HACEK organisms
- haemophilus spp
- aggregatibacter spp
- cardiobacteriium
- eikenella sp
- kingella sp.
2) non-HACEK
what is the major criteria required to diagnose infective endocarditis?
1) 2 separate positive blood cultures with microorganisms typical for infective endocarditis: viridans, streptococci, streptococcus bovid, HACEK group, staphylococcus aureus
2) echocardiogram of endocardial involvement
- typical valvular lesions: vegetation, abscess or new partial dehiscence of prosthetic valve
3) new valvular regurgitation
what is the minor criteria for diagnosing infective endocarditis?
1) predisposition heart conditions or IV drug user
2) temperature greater than 38degrees
3) vascular phenomenon
4) immunological phenomenon
5) microbiological evidence: positive blood culture but not meeting major criteria
what is the gram positive cocci in clusters called?
= staph
what is the most common coagulase-negative staphylococcus?
staphylococcus epidermidis
how do you most commonly get the bacteria staphylococcus epidermidis?
- skin contaminants
BUT - can infect prothetic material e.g. intra-vascular line infections, prosthetic heart valves
what is an example of another skin contaminate?
= corynebacterium sp
what are the presenting symptoms of acute endocarditis?
= overwhelming sepsis
= cardiac failure
what is the presenting symptoms of acute endocarditis usually due to?
= staphylococcus aureus
what are the presenting symptoms and signs of sub-acute endocarditis?
SYMPTOMS:
- fever
- malaise
- weight loss
- tiredness
- breathlessness
SIGNS:
- fever
- new or changing heart murmur
- finger clubbing
- splinter haemorrhages
- splenomegaly
- Roth spots (retinal haemorrhages), Osler nodes, (painful red lesions on palms and soles), janeway lesions (hodular haemorrhagic lesions on palms and soles)
- microscopic haematuria
what type of streptococci makes up viridans group streptococci and give examples?
= alpha haemolytic strep
- strep. mitis
- strep. sanguinis
- strep. mutans
- strep. salivarius
what 2 important things should you be aware of in sub-acute endocarditis?
- normal oral commensals
- no lance field groups
e. g. no catalase negative bacteria
what 2 types of prosthetic valve endocarditis can you present with?
1) early
2) later
when does early prosthetic valve endocarditis usually occur?
and
what organisms usually cause prosthetic valve endocarditis?
= usually infected at time of valve insertion
- staphylococcus epidermidis
- staphylococcus aureus
when does late prosthetic valve endocarditis usually occur?
and
what causes prosthetic valve endocarditis?
= many years after valve insertion
- duet to co-incidental bacteraemia
= wide range of possible organisms
what side of the heart are people who inject drugs (PWID) usually most likely to develop endocarditis?
= right side of heart (tricuspid»_space; mitral > aortic)
what organism usually causes endocarditis in PWID?
= staphylococcus aureus
how would you treat native valve endocarditis caused by viridans strep?
- amoxicillin
& - gentamicin IV
how would you treat prosthetic valve endocarditis?
- vancomycin & gentamicin IV
- add in 3 to 5 (delayed) rifampicin PO
- often valve replacement required
how would you treat drugs users endocarditis (MSSA)?
- flucloxacillin IV
how would you specifically treat staphylococcus aureus (not MSSA)?
= flucloxacillin IV
how would you specifically treat viridans streptococci?
= Benzylpenicillin iv & gentamicin iv (synergistic)
how would you specifically treat enterococcus sp?
= Amoxicillin/ vancomycin & gentamicin IV
how would you specifically treat staphylococcus epidermidis?
= Vancomycin & gentamicin IV & rifampicin PO
what monitoring therapy should be done?
- IV antibiotics usually given for 4-6weeks
- monitor cardiac function, temperature and serum C reactive protein (CRP)
- if failing an antibiotic therapy, consider referral for surgery early
in what type of people is myocarditis most commonly seen?
= in young people (causing sudden death)
what are the symptoms and signs of myocarditis?
Symptoms
- fever
- chest pain
- shortness of breath
- palpitations
Signs
- arrhythmia
- cardiac failure
what is myocarditis mainly caused by?
= enteroviruses
e. g.
- coxsackie A & B
- echovirus
how do you diagnose myocarditis?
= viral PCR
- throat swab for influenza and stool for enteroviruses
what often occurs along side myocarditis?
= pericarditis
what is the main feature of pericarditis?
= chest pain
what is the main cause of pericarditis?
= viral mainly
- bacteria less common
e. g. post cardiothoracic surgery, rarely secondary spread from endocarditis or pneumonia treatment
how would you treat pericarditis?
- antibiotics
- drainage
give examples of some causes of pericardial diseases?
1) viral
- coxsackievirus, echovirus, adenovirus, EBV, CMV, influenza, varicella, rubella, HIV, hepatits, B mumps
2) bacterial
- staphylococcus
- streptococcus
- pneumococcus
- haemophilus
- neisseria
- chlamydia
- legionella
- tuberculosis
- salmonella
- lyme disease
3) mycoplasma
4) fungal
- asperigillosis
- blastomycosis
5) parasitic
6) infective endocarditis with valve ring abscess
