leptotrichia buccalis leptotrichia buccalis leptotrichia buccalis is an anaerobic, gram-negative rod bacteria. it is a constituent of normal oral flora. leptotrichia buccalis scientific classification domain: bacteria phylum: fusobacteriota class: fusobacteriia order: fusobacterales family: leptotrichiaceae genus: leptotrichia species: l. buccalis binomial name leptotrichia buccalistrevisan 1879 morphology leptotrichia species are typically large, fusiform-shaped, non-sporulating, and non-motile rods. pathology almost every case of severe infection with leptotrichia buccalis reported in medical literature occurred in patients with neutropenia.