The susceptibilities of 43 pharyngeal isolates of Capnocytophaga to beta-lactam antibiotics, alone or in combination with beta-lactamase inhibitors, were tested by an agar dilution method. The 34 beta-lactamasepositive strains were highly resistant to beta-lactams, but the intrinsic activities of clavulanate, tazobactam, and sulbactam against Capnocytophaga, even beta-lactamase producers, indicates that these beta-lactamase inhibitors could be used for empirical treatment of neutropenic patients with oral sources of infection.The genus Capnocytophaga is composed of a group of capnophilic, gram-negative fusiform bacteria that are part of the normal oral flora in humans and animals. Capnocytophaga species have been identified as the cause of a variety of infections in immunocompetent hosts (18). In immunocompromised and neutropenic patients, Capnocytophaga spp. have been isolated more frequently from patients with bloodstream infections, including bacteremia (2, 5, 9), and patients with endocarditis (4) with severe chemotherapy-induced ulcerations (8). Variations in the prevalence, number, and proportion of Capnocytophaga spp. have been shown to occur in the dental plaque of pediatric cancer patients undergoing a course of immunosuppressive chemotherapy (22). In general, many antibiotics, including penicillins, clindamycin, macrolides, and quinolones, are effective in treating Capnocytophaga infections (6,10,11,21). However, strains that produce beta-lactamases and that cause septicemia have recently been described (1,7,9,19). These beta-lactamase-producing strains increase the risk of infection in neutropenic patients, especially during chemotherapy. The aim of this study was to determine the susceptibilities of 43 Capnocytophaga strains isolated from neutropenic pediatric patients to beta-lactams and beta-lactamase inhibitors.Forty-three Capnocytophaga strains were isolated by swabbing the throats of pediatric cancer patients undergoing a course of chemotherapy in the Department of Pediatric Oncology at Centre Hospitalier Universitaire Sud (Rennes, France). Two reference strains (Escherichia coli CIP 7624 and Staphylococcus aureus CIP 7625) were also included in the study. Throat samples were collected with sterile swabs, which were immediately taken to the Department of Microbiology, dispersed in sterile distilled water, and inoculated onto TBBP agar (4% Trypticase soy agar supplemented with 5% sheep blood, 0.1% yeast extract [AES Laboratory, Combourg, France], 100 g of polymyxin per ml, 50 g of bacitracin [Sigma] per ml) (15). The agar plates were incubated in a 10% CO 2 atmosphere for 5 days at 37°C. The isolates were identified on the basis of colony morphology, Gram staining, negative catalase and oxidase reactions, and API ZYM profiles (BioMérieux, Marcy l'Etoile, France) (13, 23).All isolates were tested for beta-lactamase production by a chromogenic cephalosporin nitrocefin method (Cefinase; BBL Microbiology Systems, Cockeysville, Md.) by the recommended procedure (Becton Dickinson). The test results we...
