Oral mucosal damage is a common complication in patients with hematopoietic malignancies, and the main strategies for palliative treatment are oral moisturization and pain management. Repair of the oral mucosa takes about 2 weeks; however, the development of a neutropenic state can delay recovery and increase the risk of infection by endogenous oral bacteria. In some cases, mucosal damage may serve as a gateway to bloodstream infection [1].

The genus Capnocytophaga consists of facultative anaerobic Gram-negative rods that are endogenous in the human oral cavity and in animals. Nine strains have been identified: C. sputigena, C. gingivalis, C. ochracea, C. granulosa, C. haemolytica, C. leadbetteri, C. canis, C. canimorsus, and C. cynodegm. The first six of these strains are endogenous to the human oral cavity, while the latter three are endogenous to the oral cavity of cats and dogs [2]. Capnocytophaga spp. can cause opportunistic infections in immunocompromised patients, although these infections are rare [3].

Capnocytophaga spp. has recently been found to harbor resistance genes such as Capnocytophaga sputigena β-lactamase-1 (CSP-1) and cfxA, which encode extended-spectrum class A beta-lactamases [4]. Accordingly, when selecting antibiotics, it is important to know whether the isolated Capnocytophaga spp. harbors resistance genes.

Here, we report a patient with acute lymphoblastic leukemia (ALL) who developed bacteremia from an oral mucosal injury site caused by C. sputigena, an endogenous human oral bacterium.