Haemophilus endocarditis. Report of 14 patients.

From 1963 through December 1976, 14 patients with Haemophilus endocarditis were seen, 10 since January 1972. Four different species representing 15 isolates were cultured from the 14 patients: H. influenzae (1), H. aphrophilus (5), H. PARAPHROPHILUS (5), and H. parainfluenzae (4). One patient had infection with both H. aphrophilus and H. paraphrophilus. Minimal inhibitory concentrations of 12 of the tested 14 strains with ampicillin were 1.25 mug/ml or less. Tube dilution tests were not possible for minimal bactericidal concentrations (7 times) or serum bactericidal titers (5 times) of the 12 tested strains. The clinical picture varied from an insidious onset and mild uncomplicated disease to abrupt onset with severe multisystem disease. Twelve patients had murmurs on admission; congestive heart failure was absent in all 14 but embolization occurred in 6. Treatment periods of 3 to 7 weeks consisted of penicillin G or ampicillin plus aminoglycoside in nine patients and ampicillin alone in five. All 14 patients were cured; no relapses occurred. Value surgery was not needed for bacteriologic cure but was necessary 15 days after therapy in one patient and in four others from 12 to 22 months after therapy. We believe that ampicillin, 12 g/day alone for 3 weeks, is adequate treatment for Haemophilus endocarditis.