Antimicrobial susceptibility of Capnocytophaga

Abstract

Capnocytophaga (Bacteroides ochraceus, Center for Disease Control biogroup DF-1) is associated with sepsis in granulocytopenic patients and is isolated in large numbers from the affected periodontal pockets in patients with juvenile periodontosis. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of 17 antimicrobial agents for 13 strains of Capnocytophaga organisms were determined. In addition, the ratio of the MBC to the MIC for each antimicrobial agent was determined for each strain. At concentrations of 1 ,ug/ml or less, penicillin, ampicillin, carbenicillin, erythromycin, and clindamycin killed 90% of the strains. At concentrations of 3.12 ,ig/ml or less, tetracycline, metronidazole, cefoxitin, and chloramphenicol killed 90% of the strains. None of the aminoglycosides tested demonstrated antibacterial activity at 50 jig/ml. Penicillin, ampicillin, carbenicillin, and cefoxitin exhibited MBC/ MIC ratios of 4 or less with all strains. Erythromycin, tetracycline, and metronidazole exhibited MBC/MIC ratios of 4 or less for 12 of 13 strains. The MICs of cephalothin and cefazolin for 90% of the strains were 25 and 50 ,tg/ml, respectively.The MBC/MIC ratios for these drugs were 4 or less for 12 of 13 and 7 of 13 strains, respectively. The MIC of cefamandole for 90% of the strains was 3.12 jig/ ml; however, only nine strains had an MBC/MIC ratio of 4 or less.The generic designation Capnocytophaga has recently been given to a group of gram-negative, gliding bacilli which are part of the normal oral flora and have been isolated in large numbers from the periodontal lesions of patients with localized juvenile periodontitis (4). These organisms are facultatively anaerobic, capnophilic, fusiform, and dysgonically fermnenting rods. Newman et al. (5) and Williams et al. (7) demonstrated in 1979 the synonymy of Capnocytophaga, Bacteroides ochraceus, and Center for Disease Control biogroup DF-1.We recently documented Capnocytophaga as the cause of sepsis in patients with malignancy complicated by profound granulocytopenia and oral mucositis (3). Since Capnocytophaga organisms appear to be opportunistic pathogens in immunosuppressed patients, and since few data are available regarding their antimicrobial susceptibility, we determined the minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of 10 clinical isolates and three reference strains of Capnocytophaga to 17 antimicrobial agents. MATERIALS AND METHODSBacteriological studies. Organisms were identified both by conventional methods (6) and by the buffered single substrate technique described by Blachman and Pickett (1). Six isolates were recovered from the blood of as many patients with granulocytopenia and malignancy. Four isolates were obtained from the periodontal pockets of patients seen in the Periodontal Clinic, University of California-Los Angeles School of Dentistry. Three strains were stock cultures of Capnocytophaga sputigena, C. ochracea, and C. gingivalis, provided by S. S. Socransky (F...

In vitro susceptibility of Capnocytophaga strains to 18 antimicrobial agents

“…Chloramphenicol and clindamycin were also active against all strains. These results are in general agreement with previously published reports (2,4,8). However, our strains Results with antimicrobial agents used in selective media for anaerobes and other oral bacteria indicated that, at concentrations in common use-colistin (10 ,ug/ml), kanamycin (75 or 100 ,tg/ml, nalidixic acid (15 ,ug/ml)-Capnocytophaga would not be inhibited.…”

“…Chloramphenicol and clindamycin were also active against all strains. These results are in general agreement with previously published reports (2,4,8 …”

Minimal inhibitory concentrations of various antimicrobial agents for human oral anaerobic bacteria

“…MICs of metronidazole for Capnocytophaga spp. agree with those of some previotis reports (9,23) but are lower than those reported by Sutter et al (33). Erythromycin MICs for oral S. mutans in the present study were higher than those found for S. mutans from endocarditis patients (2) but were also higher than those reported for oral streptococci (36).…”

IDENTIFICATION AND MODE OF ACTION OF ANTIBACTERIAL COMPONENTS FROM <I>MELASTOMA MALABATHRICUM</I> LINN LEAVES

“…The ratio of MBC to the MIC has been used to differentiate between the bactericidal and bacteriostatic activity. If the ratio > 4 the antimicrobial agent is considered to be bactericidal while if it is more than <4, the antimicrobial agent is considered to have bacteriostatic properties (Forlenza et al, 1981). The ratio of MICs to the MBCs for MMML, ML5 and Kf of each of the 17 isolates was shown in Table 2.…”