the strongest risk factor for developing infective endocarditis is a previous episode of endocarditis.
Other factors include: •
Previously normal valves (50%, typically acute presentation) •
Rheumatic valve disease (30%) •
Prosthetic valves •
Congenital heart defects •
Intravenous drug users (IVDUS, e.g. Typically causing tricuspid lesion)
Causes of infective endocarditis
Streptococcus viridans (most common cause - 40-50%) → has good prognosis •
Staphylococcus epidermidis (especially prosthetic valves) •
Staphylococcus aureus (especially acute presentation, IVDUS) •
Streptococcus bovis is associated with colorectal cancer •
Bacteroides fragilis endocarditis is very rare complication of colonic resection, bacteria reaches heart via venous return, this is why it affects right > left side → Treat with Metronidazole •
Non-infective: systemic lupus erythematosus (Libman-Sacks), malignancy: marantic endocarditis •
Culture negative causes (BP-CHB) of infective endocarditis
Brucella •
Prior antibiotic therapy •
Coxiella burnetii •
HACEK: Hemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella) •
Bartonella
Following prosthetic valve surgery Staphylococcus epidermidis is the most common organism in the first 2 months and is usually the result of perioperative contamination. After 2 months the spectrum of organisms which cause endocarditis return to normal, except with a slight ↑ in Staph aureus infections
Poor prognostic factors of infective endocarditis
Staph aureus infection •
Prosthetic valve (especially 'early', acquired during surgery) •
Culture negative endocarditis •
Low complement levels •
Diagnosis of infective endocardiris
Pathological criteria positive, or
2 major criteria, or
1 major and 3 minor criteria,or
5 minor criteria
Pathoigicaial criteria of infective endocarditis
Positive histology or microbiology of pathological material obtained at autopsy or cardiac surgery (valve tissue, vegetations, embolic fragments or intracardiac abscess content)
Major crietria of infective endocarditis
1. Positive blood cultures •
Two positive blood cultures showing typical organisms consistent with infective endocarditis, such as Streptococcus viridans and the HACEK group. •
Persistent bacteremia from two blood cultures taken > 12 hours apart or three or more positive blood cultures where the pathogen is less specific such as Staph aureus and Staph epidermidis. •
Positive serology for Coxiella burnetii, Bartonella species or Chlamydia psittaci. •
Positive molecular assays for specific gene targets
2. Evidence of endocardial involvement •
Positive echocardiogram (oscillating structures, abscess formation, new valvular regurgitation or dehiscence of prosthetic valves), or
New valvular regurgitation
Minor criteria of infective endocarditis
Predisposing heart disease •
Microbiological evidence does not meet major criteria •
Fever > 38ºc •
Vascular phenomena: major emboli, splenomegaly, clubbing, splinter hemorrhages, petechiae or purpura •
Immunological phenomena: glomerulonephritis, Osler's nodes, Roth spots (boat shaped hemorrhages in retina) •
Elevated CRP or ESR
Current management guidelines (source: British National Formulary) of infective endocarditis
Initial blind therapy - flucloxacillin + gentamicin (benzylpenicillin + gentamicin if symptoms less severe) •
Initial blind therapy if prosthetic valve is present or patient is penicillin allergic - vancomycin + rifampicin + gentamicin •
Endocarditis caused by staphylococci - flucloxacillin (vancomycin + rifampicin if penicillin allergic or MRSA) •
Endocarditis caused by streptococci → benzylpenicillin + gentamicin (vancomycin + gentamicin if penicillin allergic)
Indications for surgery in infective endocarditis
Severe valvular incompetence (both native and prosthetic) •
Early prosthetic valve endocarditis •
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
HACK group, brucella, coxilla, pseudo- aeruginosa and vancomycin resistant enterococci
The 2008 guidelines from NICE have radically changed the list of procedures for which antibiotic prophylaxis is recommended
the following procedures do not require prophylaxis:
Dental procedures •
Upper and lower gastrointestinal tract procedures •
Genitourinary tract; this includes urological, gynecological and obstetric procedures and childbirth • Upper and lower respiratory tract; this includes ear, nose and throat procedures and bronchoscopy
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