The plaque-derived gram-negative microorganism Y4 identified as a member of the genus Actinobacillus, was tested for a soluble cytotoxic factor(s). Sonication or incubation of viable Y4 microorganisms in distilled water or normal human serum resulted in liberation of a soluble material which was cytotoxic in vitro for human polymorphonuclear leukocytes (PMNs). The Y4 soluble sonic extract was also cytotoxic to human peripheral blood monocytes. However, human lymphocytes, platelets, and fibroblasts, as well as rabbit, rat, and mouse leukocytes and chicken embryo fibroblasts, were not killed by exposure to the Y4 sonic extract. No hemolytic activity was detected in the Y4 sonic extract. Consequently, the factor(s) in the Y4 sonic extract was referred to as Y4 leukotoxin. The Y4 leukotoxin was inactive at 40C, heat sensitive (560C, 30 min), and inactivated by proteases. The cytotoxic effect of Y4 leukotoxin on PMNs was dose, time, and temperature dependent. The leukotoxin did not bind to viable PMNs at 40C but

Enterococci are potential pathogens in many human body sites. This study determined the subgingival occurrence and the in vitro antimicrobial susceptibility of enterococci in 100 persons with early-onset periodontitis and 545 persons with advanced adult periodontitis. Subgingival microbial samples were collected with paper points, transported in VMGA III and plated onto anaerobic enriched brucella blood agar or selective Enterococcosel agar (BBL Microbiology Systems). Enterococcal speciation was performed using commercial micromethod kit systems. In vitro sensitivity was determined using a commercial kit system and an agar dilution assay. Subgingival enterococci occurred in 1% of early-onset periodontitis patients and in approximately 5% of adult periodontitis patients. Enterococcus faecalis was the only enterococcal species recovered, and all but one isolate belonged to the same biotype. In vitro antimicrobial sensitivity testing revealed subgingival enterococci resistant to therapeutic levels of penicillin G, tetracycline, clindamycin and metronidazole, but relatively sensitive to ciprofloxacin and amoxicillin/potassium clavulanate (Augmentin). Enterococci may populate periodontal pockets as superinfecting organisms and, in heavily infected patients, may contribute to periodontal breakdown.

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Sixty-eight strains of capnophilic fusiform Gram-negative rods from the human oral cavity were subjected to extensive physiologic characterization, tested for susceptibility to various antibiotics, and the mol-percent guanine plus cytosine of each isolate determined. The characteristics of the isolates were compared with 10 fresh and 2 stock isolates of Fusobacterium nucleatum. The isolates clearly differed from the Fusobacterium species on the basis of mol-percent guanine plus cytosine, end products, growth in a capnophilic environment and fermentation of carbohydrates. All of the gliding isolates required CO2 and formed acetate and succinate, but not H2S, indole or acetylmethylcarbinol. All fermented glucose, sucrose, maltose and mannose. The organisms may be differentiated on the basis of fermentation of additional carbohydrates, hydrolysis of polymers and reduction nitrate. Three species are proposed: Capnocytophaga ochracea, Capnocytophaga sputigena and Capnocytophaga gingivalis. Ten isolates did not fit into the proposed species.