[Infective endocarditis caused by unusual microorganisms].
All series of infective endocarditis had a variable proportion of cases without an etiologic agent because all cultures were negative. New microbiologic techniques have permitted the discovery of the role of many microorganisms in infective endocarditis. C. burnetii is an increasing causative agent of subacute infective endocarditis. In the diagnosis, to the detection of antiphase-I antibodies, immunohistochemical, molecular techniques and cellular cultures have been added. Total cure is difficult to obtain. The combination of doxicicline plus ciprofloxacin for at least 3 years has been proposed as the treatment of choice. Surgery must be reserved for patients with cardiac insufficiency. Less than 2% of cases of acute brucellosis are complicate with infective endocarditis. Infective endocarditis produces serious and rapid valvular destruction with high mortality rates if valve surgery is not performed. For medical treatment at least 3 active agents are required. Bartonella has recently been described as an etiologic agent of infective endocarditis. It mainly affects to homeless people living in poor hygienic conditions. The aortic valve is most commonly involved and, frequently, valve insufficiency requires valve replacement. Blood culture isolation needs long incubation periods. Parenteral nutrition, immunosuppression, wide spectrum antibiotic regimens, intravenous drug addiction and cardiovascular surgery are risk factors previously described in the development of fungal endocarditis. C. albicans and Aspergillus spp. are most frequent etiologic agents. Infective endocarditis should be suspected in any patient with systemic fungal disease. Blood cultures are often negative except for Candida spp. Peripheral emboli and large vegetations are frequent. Mortality is high, antifungal therapy combined with surgery is the treatment of choice. Legionella, Mycoplasma, Chlamydia, Mycobacteria, viruses are potential agents of infective endocarditis, and difficult to diagnose because of special culture requirements. Epidemiological clues, serologic and molecular techniques and blood cultures could identify them.