Endocarditis most commonly occurs subacutely and is often bacterial in origin - subacute bacterial endocarditis (SBE). It usually occurs on damaged valves and in the elderly.
Strep. viridans is involved in 45% of cases, often from the teeth. Faecal Streps are also common, usually from diagnostic and operative procedures. Staphs account for 25% of cases, frequently from cellulitis or skin abscesses.
The clinical presentation is one of fever, night sweats, weight loss, and weakness, with additional symptoms due to cardiac failure or embolism. Heart murmurs are common. Also a focal renal infarction, focal nephritis or diffuse glomerulonephritis is very common, resulting in microscopic haematuria and proteinuria.
The onset of the illness may be difficult to date.
Subacute infective endocarditis is distinguished from the less common acute form of endocarditis on the basis of the virulence of the pathogenic organism involved and clinical presentation. The incidence, investigation, treatment etc. of subacute infective endocarditis is considered with the other forms of endocarditis.