Jpn. J. Infect. Dis., 61, 212-213, 2008

Short Communication Characterization and Antimicrobial Susceptibility of Dysgonomonas capnocytophagoides Isolated from Human Blood Sample Michitaka Hironaga, Kunikazu Yamane1*, Miki Inaba, Yumi Haga and Yoshichika Arakawa1 Central Clinical Laboratory, Kyushu Kousei Nenkin Hospital, Fukuoka 806-8501, and 1Department of Bacterial Pathogenesis and Infection Control, National Institute of Infectious Diseases, Tokyo 208-0011, Japan (Received December 28, 2007. Accepted February 8, 2008)

SUMMARY: Dysgonomonas capnocytophagoides belongs to a group of facultative anaerobic Gram-negative coccobacilli that was formerly designated CDC group DF-3. We evaluated the characteristics of this microbe and its susceptibility to antimicrobial agents. In this study, D. capnocytophagoides was isolated by anaerobic blood cultures from a 78-year-old male with pancreatic cancer, ischemic heart disease, and diabetes mellitus, who also showed symptoms of cholangitis. The isolated strain demonstrated resistance to various β-lactams, erythromycin, aminoglycosides, and fluoroquinolones, but was susceptible to sulfamethoxazole-trimethoprim, clindamycin, minocycline, and chloramphenicol. The results of all biochemical tests and the homology of the 16S rRNA gene were consistent with previous reports of D. capnocytophagoides.

The genus Dysgonomonas belongs to a group of facultative NF-18, and ID Test HN-20 Rapid (Nissui Pharmaceutical anaerobic Gram-negative coccobacilli (1). This genus was for- Co., Ltd., Tokyo, Japan). The culture conditions were those merly affiliated with CDC group DF-3, and was recently di- established in the manufacturers’ instructions. The bacterial vided into three : Dysgonomonas capnocytophagoides, characteristics are as follows: non-motile; oxidase, acetoin , and (2). The production, gelatinase, arginine dehydrolase, lysine de- biochemical profile of D. capnocytophagoides is similar to carboxylase, ornithine decarboxylase, and catalase-negative that of Capnocytophaga spp. However, Dysgonomonas spp. but β-galactosidase-positive; X factor auxotrophy; fermented forms a genetic cluster together with Bacteroides forsythus glucose, fructose, maltose, galactose, mannose, arabinose, lac- and Bacteroides distasonis (3) from the viewpoint of the tose, melibiose, sucrose and xylose but not inositol, rhamnose, 16S rRNA gene sequences. The pathogenic potential of D. or trehalose. It did not produce indole or H2S. It did not capnocytophagoides was reported to be limited to immuno- reduce nitrate and hydrolyzed esculin but did reduce urea. compromised hosts suffering from diseases such as leukemia No result of accurate name about this microbe demonstrated (4,5), hypogammaglobulinemia (6), and diabetes mellitus (7). these three identification kits. For amplification of the 16S This organism tends to be mainly isolated from stool (6,8- rRNA gene fragment, the primers used in this study and the 11), though it has also been found in urine (12), skin abscess polymerase chain reaction (PCR) conditions were those used (7), and blood (4,5). The present report characterizes D. by Sasaki et al. (13). PCR product sequences were determined capnocytophagoides isolated from an anaerobic blood culture with Big Dye Terminator Cycle Sequencing Ready Reaction of a patient diagnosed with cholangitis along with underly- kits and a model 3100 DNA sequence analyzer (Applied ing pancreatic cancer and diabetes mellitus. Blood cultures Biosystems, Foster City, Calif., USA). The sequences of the were taken twice: on the first and second days after admis- PCR products were determined with both PCR primers. sion. Although no bacterium was identified from the primary Nucleotide sequence alignment was performed with Sequencher blood culture, the bacterium appeared in a second aerobic version 4.2.2 (Hitachi Software Engineering Co., Ltd., Yoko- blood culture bottle after 33 h of incubation. A small Gram- hama, Japan) and GENETYX-MAC version 12.2.3 (Software negative coccoid bacterium was observed by Gram staining of the culture broth from an anaerobic blood culture bottle. The microbe was identified by its small, non-hemolytic, whitish- grey, circular and convex form and entire margin colonies with a sweet odor on sheep-blood agar after 48 h at 35°C in a CO2-enriched atmosphere (Figure 1). A similar microbe was observed on a chocolate agar plate after 48 h at 35°C in a CO2-enriched atmosphere, as well as on a Brucella HK agar plate after 48 h at 35°C in an anaerobic condition. However, no growth was observed on a MacConkey agar plate. The microbe’s biochemical characteristics were determined by API 20E (BioMerieux, Marcy l’Etoile, France), ID Test

*Corresponding author: Mailing address: Department of Bacterial Pathogenesis and Infection Control, National Institute of Infec- Fig. 1. Macroscopic observation of D. capnocytophagoides colonies. tious Diseases, 4-7-1 Gakuen, Musashi-Murayama, Tokyo 208- Colonies of small whitish-gray, circular, convex, entire, and sweet

0011, Japan. Tel: +81-42-561-0771, Fax: +81-42-561-7173, E- odor grew on sheep-blood agar after 48 h at 35°C in CO2-enriched mail: [email protected] atmosphere.

212 Table 1. Antimicrobial susceptibility testing was not a causative bacterium for cholangitis and bacteremia Antimicrobial agent MIC (μg/ml) in this patient. D. capnocytophagoides is an uncommon bac- Ampicillin >128 terium and cannot be identified by a commercial identifica- Sulbactam-cefoperazone 16 tion kit. Precise identification of this bacterium should be Cefmetazole >128 made because it can cause invasive infection, especially in Ceftazidime >128 certain immunocompromised patients such as those with Cefotaxime >128 leukemia or poorly controlled diabetes mellitus. Ceftriaxon >128 Cefepime 32 ACKNOWLEDGMENTS Imipenem 32 This work was funded in part by a Grant-in-Aid for Young Scientists (B) Sulfamethoxazole-trimethoprim 2 No. 16790318 from the Ministry of Education, Culture, Sports, Science Erythromycin >128 and Technology, Japan and grants from the Ministry of Health, Labour and Welfare, Japan (H15-Shinkou-9, H15-Shinkou-10). 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