Isolation of Capnocytophaga granulosa from an Abscess in an Immunocompetent Adolescent

The genus Capnocytophaga includes 7 species (Capnocytophaga ochracea, Capnocytophaga gingivalis, Capnocytophaga sputigena, Capnocytophaga haemolytica, Capnocytophaga granulosa, Capnocytophaga canimorsus, and Capnocytophaga cyno-degmi) characterized as gram-negative, fastidious, capnophilic rods with fusiform morphology and gliding motility. C. ochracea, C. sputigena, C. gingivalis, and, recently, C. haemolytica and also C. granulosa have been isolated from the human oral cavity and therefore may be considered members of the normal flora [1–3]. Capnocytophaga species other than C. granulosa have been reported as a cause of bacteremia and sepsis, as well as localized infections, in immunocompromised patients. In immunocompetent hosts, these Capnocytophaga species are occasionally involved in localized, mostly polymicrobial infections [4, 5]. However, data on infections by C. granulosa are lacking. We report here the isolation of C. granulosa along with Staphylococcus aureus from an abscess of a 14-year-old immunocompetent boy who presented with severe pain in the lumbosacral area 10 days after he had been kicked in the area of the os sacrum. Physical examination revealed tenderness over the os sacrum. Laboratory results included the following values: leukocytosis (WBCs, 20.5 × 109/L with 76% polymorpho-nuclear leukocytes and 4% band forms); erythrocyte sedimentation rate, 85 mm/h; and C-reactive protein, 195 mg/L. A nuclear magnetic resonance (NMR) scan of the pelvis showed a multicystic formation in the deep gluteal area with a diameter of 3 cm. The abscess was punctated under ultrasound guidance, and treatment with gentamicin was instilled. Systemic treatment was initiated with clindamycin and flucloxacillin. Treatment resulted in complete remission within 14 days. From the abscess material C. granulosa and S. aureus were isolated by use of chocolate agar incubated aerobically with 5% CO2. S. aureus was also isolated from the blood. C. granulosa was identified on the basis of the reactions listed in table 1. Cells were gram-negative with fusiform morphology and showed typical granula after 5 days incubation in glucose broth. Growth was scanty in ambient air but was stimulated by 5% CO2. The strain was catalase and oxidase negative. Glucose, lactose, maltose, sucrose, and starch, but not esculin or inulin, were fermented. Starch and esculin were not hydrolyzed, nitrate was not reduced, indole was not produced, and leucinarylamidase was not detected. By use of gas chromatography, acetic acid and succinic acid were detected, as were small amounts of lactic acid, propionic acid, and iso-valerianic acid. The strain showed a cellular fatty acid composition of iso-C15:0, C16:0, and anteiso-C15:0. Because C. granulosa has been isolated from the human oral cavity [3], we assume that the C. granulosa strain isolated from the abscess was originally a member of the flora of the oral cavity, which is likely to have reached and colonized the traumatized tissue via the bloodstream [6]. From the case presented, one may conclude that C. granulosa, as other species of Capnocytophaga, might contribute to the establishment of mixed infections in traumatized tissue because it was isolated along with a strain of S. aureus. Whether C. granulosa may also cause monobacterial infections remains to be established. Identification of Capnocytophaga species.