Serious infection with Leptotrichia buccalis. Report of a case and review of the literature.

Leptotrichia buccalis is an obligately anaerobic, gram-negative rod classified as a member of the family Bacteroidaceae. Organisms found in this family (Bacteroides and Fusobacteria) are frequent causes of severe infection in human beings. L. buccalis is a constituent of normal oral flora. Leptotrichia has rarely been recovered from mixed infections primarily of the head and neck. It has not previously been reported as a cause of serious infection in man. We report a case of cavitary pneumonia and septicemia caused by L. buccalis. The colonial morphology and gram stain of L. buccalis are characteristic. Definitive identification is made by gas-liquid chromatography. Leptotrichia have been shown to contain potent endotoxin. L. buccalis has the potential to be a virulent, pathogenic microorganism, especially in the compromised host.