[Etiology of infectious endocarditis at the Instituto Nacional de Cardiologia Ignacio Chavez from 1976 to 1986].

We studied 85 cases of infectious endocarditis (IE) with an anatomical diagnosis (biopsy or necropsy). Most cases occur between the second and fourth decade of life; male/female ratio was 1/0.8; 45 had IE in a natural valve; 40 had prosthetic IE. Clinical diagnosis was established or at least suspected in 61 cases (72%); the most common misdiagnosis was acute rheumatic fever. Blood cultures were positive in 25 cases of natural valve IE (56%) and in 25 cases of prosthetic IE (63%). Half of those negative culture cases had a history of antimicrobial use before their arrival at the hospital. Those microorganisms which cause natural valve IE were: staphylococci (9), streptococci (8), Gram negatives (5), Candida sp (1), and two non-identified cases; 1 patient had a polymicrobial infection. Prosthetic IE was divided into early and late infections. The former was due to: staphylococci (4), streptococci (1), Candida sp (1); the latter: staphylococci (7), streptococci (4), Gram negatives (4), Candida sp, Mycobacterium fortuitum and Peptococcus (1 each), and in a single case Lactobacillus sp, presumably a contaminant.