Acute infective endocarditis refers to the presence of signs and symptoms of infective endocarditis that are present for days up to six weeks. If these signs and symptoms persist for more than six weeks but less than three months, this is subacute infective endocarditis. Chronic infective endocarditis refers to the presence of such signs and symptoms when they persist for more than three months. Subacute bacterial endocarditis (SBE) is often due to streptococci of low virulence (mainly viridans streptococci) and mild to moderate illness which progresses slowly over weeks and months (>2 weeks) and has low propensity to hematogenously seed extracardiac sites. Acute bacterial endocarditis (ABE) is a fulminant illness over days to weeks (<2 weeks), and is more likely due to Staphylococcus aureus, which has much greater virulence or disease-producing capacity and frequently causes metastatic infection.This classification is now discouraged, because the ascribed associations (in terms of organism and prognosis) were not strong enough to be relied upon clinically. The terms short incubation (meaning less than about six weeks) and long incubation (greater than about six weeks) are preferred. Culture results
Infective endocarditis may also be classified as culture-positive or culture-negative. By far the most common cause of "culture-negative" endocarditis is prior administration of antibiotics.Sometimes microorganisms can take a longer period of time to grow in the culture media, for example Cutibacterium spp. and the HACEK bacteria group. Some organisms are said to be fastidious because they have demanding growth requirements. Some examples include pathogens like Aspergillus species, Brucella species, Coxiella burnetii, Chlamydia species.
Replacement of the valve with a mechanical or bioprosthetic artificial heart valve is necessary in certain situations:
Patients with significant valve stenosis or regurgitation causing heart failure
Evidence of hemodynamic compromise in the form of elevated end-diastolic left ventricular or left atrial pressure or moderate to severe pulmonary hypertension
Presence of intracardiac complications like paravalvular abscess, conduction defects or destructive penetrating lesions
Recurrent septic emboli despite appropriate antibiotic treatment
Large vegetations (> 10 mm)
Persistently positive blood cultures despite appropriate antibiotic treatment
Prosthetic valve dehiscence
Relapsing infection in the presence of a prosthetic valve
Abscess formation
Early closure of mitral valve
Infection caused by fungi or resistant Gram-negative bacteria.The guidelines were recently updated by both the American College of Cardiology and the European Society of Cardiology. There was a recent meta-analysis published that showed surgical intervention at seven days or less is associated with lower mortality. Prognosis
Infective endocarditis is associated with 18% in-hospital mortality. As many as 50% of people with infective endocarditis may experience embolic complications. Epidemiology
In developed countries, the annual incidence of infective endocarditis is 3 to 9 cases per 100,000 persons. Infective endocarditis occurs more often in men than in women. There is an increased incidence of infective endocarditis in persons 65 years of age and older, which is probably because people in this age group have a larger number of risk factors for infective endocarditis. In recent years, over one-third of infective endocarditis cases in the United States was healthcare-associated. Another trend observed in developed countries is that chronic rheumatic heart disease accounts for less than 10% of cases.