The diagnosis of endocarditis requires a high index of suspicion. The condition must be considered and carefully excluded in all patients with a heart murmur and fever of undetermined origin that persists for more than a few days. Diagnosis is made in the majority of patients by three or four separate sets of blood cultures taken from a separate vein puncture site over 24 h.
Transesophageal echocardiography (TEE) is superior to transthoracic assessment in the search for infected vegeta¬tions located on heart valves and is crucial for the diagnosis of endocarditis. Transthoracic two-dimensional Doppler echocardiography gives poor detection of prosthetic heart valves, especially in the mitral position, and of calcific sclerotic native valves. Vegetations that are less than 5 mm, 6–10 mm, or greater than 10 mm are observed in 25, 65, and 70%, respectively, by transthoracic technique. This is 100% for all lesions using TEE.
Bacterial endocarditis is caused most often by infection with Streptococcus viridans (~40%) followed by S. aureus (~30%) enterococci in about 10–15% of cases. Other organisms include Staphylococcus mitis, S. bovis, S. anginosus, Haemophilus influenzae, Pseudomonas aeruginosa, P. cepacia, and Serratia marcescens. gentamicin (1–1.5 mg/kg every 8 h) and monitor levels and adjustment for renal function. Gentamicin is given for 4 weeks. 4. S. aureus: Methicillin-sensitive strains constitute the most cases of S. aureus endocarditis and these are treated with nafcillin or cloxacillin (at doses given above) or flucloxacillin (IV 2 g every 4 h) plus optional addition of gentamicin (1 mg/kg every 8 h IV) for 4–7 days; the dose is to be monitored by levels. The dose is reduced in elderly patients and those with renal dysfunction, whereas the dosing interval is increased. Gentamicin is discontinued after 1 week, and nafcillin or flucloxacillin IV is continued for 5–6 weeks. The length of treat¬ment is usually from 4–6 weeks. In the UK, S. aureus endocarditis is usually treated with IV flucloxacillin from 4–6 weeks and gentamicin IV for 14 days.

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