Capnocytophaga

Abstract

Capnocytophaga is a genus in the family Flavobacteriaceae1 and members belong to the Flavobacterium-Cytophaga ribosomal RNA homology group.2 Capnocytophaga species were first isolated from the human oral cavity by Prevot in 1956 as Fusobacterium nucleatum var. Ochraceus. The term "Capnocytophaga" means "eater of carbon dioxide" 3 and comprises a group of capnophilic, facultatively anaerobic as well as gram-negative fusiform rods. These microorganisms are short-to-elongated flexible rods or filaments, 0.42–0.6 μm in diameter and 2.5–5.7 μm in length. The ends of the cells are usually rounded or tapered (Figure 44.1a). Capnocytophaga species can be pleomorphic and they do not form capsules and sheaths. The colonial morphology is usually flat, presenting concentrically spreading growth from a central point of inoculation (Figure 44.1b). The key characteristics of this genus are listed in Table 44.1.