Antimicrobial susceptibility of Capnocytophaga.

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 microgram/ml or less, penicillin, ampicillin, carbenicillin, erythromycin, and clindamycin killed 90% of the strains. At concentrations of 3.12 microgram/ml or less, tetracycline, metronidazole, cefoxitin, and chloramphenicol killed 90% of the strains. None of the aminoglycosides tested demonstrated antibacterial activity at 50 microgram/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 microgram/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 microgram/ml; however, only nine strains had an MBC/MIC ratio of 4 or less.

Capnocytophaga sepsis: a newly recognised clinical entity in granulocytopenic patients.

10 episodes of Capnocytophaga sepsis occurred in 6 patients with granulocytopenia, malignancy, and oral mucosal ulcerations. Capnyocytophaga is a newly described genus of gliding gram-negative bacilli which is physiologically and genetically identical to Bacteroides ochraceus and biogroup DF-1 of the United States Center for Disease Control and is commonly responsible for periodontal infections.

Detection, identification, and comparison of Capnocytophaga, Bacteroides ochraceus, and DF-1.

Working independently, three laboratories had recognized considerable similarity among certain strains of dysgonic, fermentative, capnophilic, surface translocating, gram-negative bacilli referred to as Capnocytophaga, Bacteroides ochraceus, and Center for Disease Control biogroup DF-1. To determine the relationship among these groups, 21 strains were exchanged and independently characterized by the three laboratories. Additionally, a fourth laboratory examined the deoxyribonucleic acid homologies of the same strains. Using methods common to dental microbiology, eight of the strains had been isolated from the gingival sulcus and periodontal lesions and identified as Capnocytophaga. Three strains isolated from blood and transtracheal aspirate had been characterized by conventional anaerobic methods and recorded as B. ochraceus. Ten strains isolated from sputum, blood, throat, spinal fluid, and tracheal aspirate had been identified as DF-1 with the methods of E. O. King and a buffered single-substrate technique. All strains were similar in respect to colonial and microscopic morphology, surface translocation, biochemical features, gas-liquid chromatograms of metabolic end products, and deoxyribonucleic acid composition. We conclude that these biogroups should be termed Capnocytophaga species.

Nonfermentative bacilli: evaluation of three systems for identification.

Three systems for the identification of nonfermentative bacilli were evaluated for their rapidity and accuracy of identification of 217 strains. Two of the systems, API 20E (API) and Oxi/Ferm tube (OxiF), are available as kits; the oxidative attack (OA) system is not commerically available. The overall accuracies of the OA, API, and OxiF systems were 91, 69, and 50%, respectively. Identification within 48 h was achieved for 98% of the strains by OA, for 50% by API, and for 18% by OxiF. Most of the organisms that were either misidentified or not identified by API and OxiF were those nonfermentative bacilli which are relatively more fastidious or rarely encountered or both. All three systems accurately identified nonfermentative bacilli commonly isolated at Olive View Medical Center, namely, Pseudomonas aeruginosa, Acinetobacter anitratus, Pseudomonas maltophilia, Acinetobacter lwoffi, saccharolytic flavobacteria (CDC IIb), moraxellae, Pseudomonas fluorescens, and Pseudomonas putida. The OA system identified 100% of the above organisms correctly, API identified 99.4%, and OxiF identified 99.3%. Since these organisms comprise 92% of the total number of nonfermentative bacilli isolated at Olive View Medical Center, we conclude that both API and OxiF may be useful alternatives to conventional methods, based on accuracy of identification alone. These two systems were considered substantially inferior to the OA system when both accuracy and rapidity of identification were taken into account.

Bacteriology of human and animal bite wounds.

Seventy-three patients with bite wounds (16 patients with clenched-fist injuries, 18 with human bite wounds, and 39 with animal bites) were cultured aerobically and anaerobically. A total of 33 of 34 patients with human bites and clenched-fist injuries and 33 of 39 patients with animal bites had aerobic or facultative bacteria isolated from their wounds. A total of 224 strains of aerobic or facultative bacteria were isolated, the most frequent isolate being alpha-hemolytic streptococci (50 strains). Staphylococcus aureus was isolated from 18 wounds. Penicillin-resistant gram-negative rods were infrequently isolated (12 strains). Anaerobic bacteria were isolated in 18 of 34 human bite wounds and clenched-fist injuries and 16 of 39 animal bite wounds. A total of 88 anaerobic strains was isolated, the most common being various Bacteroides species (36 strains).

Experimental Cholera in Chinchillas: the Immune Response in Serum and Intestinal Secretions to Vibrio cholerae and Cholera Toxin.

The immune response to Vibrio cholerae and cholera toxin was studied in chinchillas inoculated intra-intestinally with 10(8) viable V. cholerae 596B. Sera and intestinal fluids were collected from animals on days 1, 2, 3, 5, 7, 10, 14, 30, and 60 postinoculation, and antibodies were quantified by various methods. When radiovibriolytic and radiotoxin precipitin tests were used, a significant (fourfold) rise in both antibacterial and antitoxic titers was detected in intestinal fluids on the 2nd day of infection. In contrast, a significant rise in serum antibodies occurred between days 3 and 5. Since the acute phase of the chinchilla disease lasts 1 to 3 days, recovery coincided with rise in intestinal antibody but not with rise in serum antibody. Our results indicate that both antibacterial and antitoxic mechanisms are operative in chinchilla cholera and that the initial and crucial immune response is local in nature.

Radiobacteriolysis: a new technique using chromium-51 for assaying anti-Vibrio cholerae antibodies.

A new method for detecting and quantitating antibodies against Vibrio cholerae is described. The reaction involves the release of radiochromium from prelabeled vibrios in the presence of specific antibody and complement. The entire assay can be completed within 5 hr. The method is highly reproducible, immunologically specific, temperature- and complement-dependent, and significantly more sensitive than other methods currently used for titration of anti-Vibrio cholerae antibodies. The technique is also potentially applicable to titration of antibodies against other gram-negative bacteria.