Because bacteremia is continuous in infective endocarditis, the timing of the culture in relation to occurrence of fever is usually unimportant. Doppler echocardiography is very valuable. In the elderly, valvular masses are not synonymous with vegetations and may result from valvular sclerosis or myxomatous degeneration of the valve. Transesophageal echocardiography is helpful when the standard transthoracic approach to imaging is too difficult technically or is not diagnostic. It can detect multiple vegetations, satellite lesions, fistulas, annular abscesses, valvular perforations, and aneurysms when transthoracic echocardiography shows only a vegetation.
Optimal treatment requires use of microbicidal drugs.
For acutely ill patients, empiric therapy should be started immediately after obtaining blood for culture, so that valvular damage can be limited. Initially, selection of antimicrobial therapy is based on which microorganism is most likely in the specific clinical setting. If onset is subacute in a patient who does not use IV drugs and who has native valve endocarditis, infection with streptococci or enterococci is likely. If onset is acute or if the patient uses IV drugs, therapy should target S. aureus. If the patient has a prosthetic valve, vancomycin can be used to target resistant strains of S. aureus and S. epidermidis .