Bacterial endocarditis due to Haemophilus parainfluenzae

We have evaluated three patients with Haemophilus parainfluenzae endocarditis. Two of the three had underlying heart disease. All presented with fever, chills and malaise of less than two weeks' duration. Mitral valve involvement led to congestive heart failure in two of three cases. Treatment proved difficult, despite normally adequate dosages of antibiotics to which the pathogens were sensitive in vitro (ampicillin, 12-20 gm/dag; gentamicin, 3-5 mg/kg/day). Two patients were cured; one died. There was a suggestion of an inverse correlation between vegetation mass and favorable clinical response. Review of the English literature disclosed 22 documented cases of H parainfluenzae endocarditis, including 12 in the antibiotic era.