Infective endocarditis caused by uncommon bacteria.

The present study is an attempt to define the uncommon bacteria (UB) causing endocarditis and to evaluate their prevalence and clinical significance. Review of 13 series (including ours) revealed that UB were the infecting organisms in 105/1989 patients (5.3%). The leading bacteria were: Pneumococcus, Haemophilus sp., Corynebacterium sp., Neisseria sp., Streptobacillus moniliformis, Cardiobacterium hominis and Erysipelothrix sp. These data are similar to those obtained from 111 sporadic case reports published in English during the last 6 yr and cited in the Index Medicus. Infection by UB usually resembles that by the common bacteria. However, Haemophilus sp. seems to affect mainly the young and is associated with major arterial occlusions, and Brucella is claimed to have a greater affinity to the aortic valve. UB are more frequent in patients with polymicrobial infections and their diagnosis is often delayed. Greater awareness to the possibility of infections with UB is needed for early diagnosis and improved prognosis.