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Diagnosis and treatment of infective endocarditis
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INFECTIVE ENDOCARDITIS Professor/mohammed Ahmed Bamashmos
Infection of cardiac endothelium. • Infective endocarditis (IE), also called bacterial endocarditis (BE), is an infection caused by bacteria that enter the bloodstream and settle in the heart lining, a heart valve or a blood vessel. • Infective endocarditis is due to microbial infection of ; • a heart valve (native or prosthetic), • the lining of a cardiac chamber or blood vessel, • or a congenital anomaly (e.g. septal defect). • IE is uncommon, but people with some heart conditions have a greater risk of developing it.
Colonization of heart valves with microbial organisms causing friable infected vegetation & valve injury. • Bacterial Endocarditis produces large vegetation & may affect any valvein the Heart,although Left sided lesions of Aortic & Mitral valve are more common. • The proliferation of microorganisms on the endothelium of the heart results in Infective endocarditis.
Microbial Etiology of Infective Endocarditis Based on Risk Factors
Types • Acute infective endocarditis • Toxic presentation • Progressive valve destruction and metastatic infection developing in days to weeks • Most commonly caused by S. aureus • Subacute Infective endocarditis • Mild toxicity • Presentation over weeks to months • Rarely leads to metastatic infection • Most commonly S. viridans or enterococcus
Pathogenesis • When the infection is established, vegetations composed of organisms, fibrin and platelets grow and may become large enough to cause obstruction • They may also break away as emboli. • Abscesses may form • Valve regurgitation may develop or increase. • Extracardiac manifestations such as vasculitis and skin lesions are due to emboli or immune complex deposition. • Mycotic aneurysms may develop .
A common mnemonic for the signs and symptoms of Endocarditis is FROM JANE: • Fever • Roth's spots • Osler's nodes • Murmur • Janeway lesions • Anemia • Nail hemorrhage (splinter hemorrhages) • Emboli
One or more classic signs of IE are found in as many as 50% of patients. They include the following: • Petechiae - Common but nonspecific finding • Subungual (splinter) hemorrhages - Dark red linear lesions in the nailbeds • Osler nodes - Tender subcutaneous nodules usually found on the distal pads of the digits • Janeway lesions - Nontender maculae on the palms and soles • Roth spots - Retinal hemorrhages with small, clear centers; rare and observed in only 5% of patients.
Diagnosis(DukeCriteria) Major criteria Minor criteria • Positive blood culture - Typical organism from two cultures - Persistent positive blood cultures taken > 12 hrs apart - Three or more positive cultures taken over > 1 hr • Endocardial involvement - Positive echocardiographic findings of vegetations - New valvular regurgitation • Predisposing valvular or cardiac abnormality • Intravenous drug misuse • Pyrexia ≥ 38 °C • Embolic phenomenon • Vasculitic phenomenon • Blood cultures suggestive: organism grown but not achieving major criteria • Suggestive echocardiographic findings
Definite endocarditis = 2 major/1 major and 3 minor/ 5 minor • Possible endocarditis = 1 major and 1 minor/ 3 minor.
Investigations • Blood work: anemia (normochromic, normocytic), increased ESR and/or CRP, +RF • Urinalysis: proteinuria, hematuria, red cell casts • Serial blood cultures: 3 sets (each containing one aerobic and one anaerobic sample) collected from different sites > 1 h apart • Echo findings: vegetations, regurgitation, abscess - TEE indicated if TTE is non-diagnostic or if abscess/perforation/infection suspected. TTE inadequate in 20% (obesity, COPD, chest wall deformities) • ECG: increased PR interval may indicate perivalvular abscess
Diagnosis of endocarditis is usually based on clinical, microbiologic, and echocardiographic findings. • Treatment involves antimicrobial therapy targeted to the identified organism. • Surgical indications include heart failure, uncontrolled infection, and prevention of embolic events.
HACEK Organisms : • Ceftriaxone (2 g/d IV as a single dose for 4 weeks) . • Ampicillin/sulbactam (3 g IV q6h for 4 weeks)
AHA 2007 guidelines recommend IE prophylaxis • only for patients with prosthetic valve material, past history of IE, certain types of congenital heart disease or cardiac transplant recipients who develop valvulopathy • only for the following procedures - dental - respiratory tract -procedures on infected skin/skin structures/MSK structures - not GI/GU procedures specifically