Infective endocarditis Flashcards
What is the strongest risk factor for developing infective endocarditis?
A previous episode of endocarditis.
Affected patients include those with previously normal valves, rheumatic valve disease, prosthetic valves, congenital heart defects, intravenous drug users, and those with recent piercings.
Which valve is most commonly affected in infective endocarditis?
The mitral valve.
What is the most common cause of infective endocarditis?
Staphylococcus aureus.
Particularly common in acute presentations and intravenous drug users.
What was historically the most common cause of infective endocarditis?
Streptococcus viridans.
This is no longer the case, except in developing countries.
What are the two most notable viridans streptococci?
Streptococcus mitis and Streptococcus sanguinis.
They are commonly found in the mouth and dental plaque.
What is a common cause of endocarditis in patients following prosthetic valve surgery?
Coagulase-negative Staphylococci such as Staphylococcus epidermidis.
Usually the result of perioperative contamination.
What is Streptococcus bovis associated with?
Colorectal cancer.
The subtype Streptococcus gallolyticus is most linked with colorectal cancer.
What are some culture negative causes of infective endocarditis?
Prior antibiotic therapy, Coxiella burnetii, Bartonella, Brucella, and HACEK organisms.
HACEK includes Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella.
What is a non-infective cause of endocarditis?
Systemic lupus erythematosus (Libman-Sacks) and malignancy (marantic endocarditis).
What are the criteria for diagnosing infective endocarditis?
Infective endocarditis is diagnosed if pathological criteria are positive, or if there are 2 major criteria, or 1 major and 3 minor criteria, or 5 minor criteria.
What constitutes pathological criteria for infective endocarditis?
Positive histology or microbiology of pathological material obtained at autopsy or cardiac surgery (valve tissue, vegetations, embolic fragments or intracardiac abscess content).
What are the major criteria for infective endocarditis?
- Positive blood cultures showing typical organisms, or persistent bacteraemia, or positive serology for specific pathogens, or positive molecular assays.
- Evidence of endocardial involvement via positive echocardiogram or new valvular regurgitation.
What are examples of typical organisms in positive blood cultures?
Typical organisms include Streptococcus viridans and the HACEK group.
What are the minor criteria for infective endocarditis?
- Predisposing heart condition or intravenous drug use.
- Microbiological evidence does not meet major criteria.
- Fever > 38ºC.
- Vascular phenomena: major emboli, splenomegaly, clubbing, splinter haemorrhages, Janeway lesions, petechiae or purpura.
- Immunological phenomena: glomerulonephritis, Osler’s nodes, Roth spots.
What are poor prognostic factors for infective endocarditis?
- Staphylococcus aureus infection
- Prosthetic valve (especially ‘early’, acquired during surgery)
- Culture negative endocarditis
- Low complement levels
What is the mortality rate according to organism for staphylococci?
30%
What is the mortality rate according to organism for bowel organisms?
15%
What is the mortality rate according to organism for streptococci?
5%
What is the suggested antibiotic therapy for initial blind therapy in native valve endocarditis?
Amoxicillin, consider adding low-dose gentamicin
What is the suggested antibiotic therapy if the patient is penicillin allergic, has MRSA, or severe sepsis?
Vancomycin + low-dose gentamicin
What is the suggested antibiotic therapy for prosthetic valve endocarditis?
Vancomycin + rifampicin + low-dose gentamicin
What is the suggested antibiotic therapy for native valve endocarditis caused by staphylococci?
Flucloxacillin
What is the suggested antibiotic therapy for native valve endocarditis caused by staphylococci if penicillin allergic or MRSA?
Vancomycin + rifampicin
What is the suggested antibiotic therapy for prosthetic valve endocarditis caused by staphylococci?
Flucloxacillin + rifampicin + low-dose gentamicin
What is the suggested antibiotic therapy for prosthetic valve endocarditis caused by staphylococci if penicillin allergic or MRSA?
Vancomycin + rifampicin + low-dose gentamicin
What is the suggested antibiotic therapy for endocarditis caused by fully-sensitive streptococci (e.g. viridans)?
Benzylpenicillin
What is the suggested antibiotic therapy for endocarditis caused by fully-sensitive streptococci if penicillin allergic?
Vancomycin + low-dose gentamicin
What is the suggested antibiotic therapy for endocarditis caused by less sensitive streptococci?
Benzylpenicillin + low-dose gentamicin
What is the suggested antibiotic therapy for endocarditis caused by less sensitive streptococci if penicillin allergic?
Vancomycin + low-dose gentamicin
What are the indications for surgery in infective endocarditis?
- Severe valvular incompetence
- Aortic abscess (often indicated by a lengthening PR interval)
- Infections resistant to antibiotics/fungal infections
- Cardiac failure refractory to standard medical treatment
- Recurrent emboli after antibiotic therapy
What did the 2008 NICE guidelines change regarding antibiotic prophylaxis for infective endocarditis?
The guidelines radically changed the list of procedures for which antibiotic prophylaxis is recommended.
Which procedures do not require antibiotic prophylaxis according to NICE?
Dental procedures, upper and lower gastrointestinal tract procedures, genitourinary tract procedures (including urological, gynaecological, obstetric procedures, and childbirth), and upper and lower respiratory tract procedures (including ear, nose and throat procedures and bronchoscopy).
What should be done for episodes of infection in people at risk of infective endocarditis?
Any episodes of infection should be investigated and treated promptly to reduce the risk of endocarditis developing.
What antibiotic should be given to a person at risk of infective endocarditis undergoing a procedure with suspected infection?
They should be given an antibiotic that covers organisms that cause infective endocarditis.
How do the NICE guidelines differ from the American Heart Association/European Society of Cardiology guidelines?
NICE guidelines do not advocate antibiotic prophylaxis for high-risk patients undergoing dental procedures, while the American Heart Association/European Society of Cardiology guidelines still recommend it.
