Conditions for the demonstration of collagenolytic activity in Bacteroides melaninogenicus

Microflora in adult periodontitis

The subgingival microflora of adult periodontitis was studied in 8 adults (36-47 years) and compared with that of 10 periodontally healthy individuals (36-43 years). A total of 64 periodontal lesions were examined, and classified according to the attachment level in three categories: attachment loss > 6 mm, attachment loss 4-6 mm and attachment loss < 4 mm. Also for comparative purposes 20 gingival sulci were evaluated. Samples were taken using three standardized paper points and were incubated anaerobically in selective and non-selective media. The results showed a statistically significant association of Capnocytophaga gingivalis and Capnocytophaga sputigena with moderate periodontal lesions, while Haemophilus segnis has been correlated to severe periodontal lesions. We concluded that C. gingivalis, C. sputigena and H. segnis might be potentially conductive to periodontal deterioration in adult periodontitis.

Factors in virulence expression and their role in periodontal disease pathogenesis

The classic progression of the development of periodontitis with its associated formation of an inflammatory lesion is characterized by a highly reproducible microbiological progression of a Gram-positive microbiota to a highly pathogenic Gram-negative one. While this Gram-negative microbiota is estimated to consist of at least 300 different microbial species, it appears to consist of a very limited number of microbial species that are involved in the destruction of periodontal diseases. Among these "putative periodontopathic species" are members of the genera Porphyromonas, Bacteroides, Fusobacterium, Wolinella, Actinobacillus, Capnocytophaga, and Eikenella. While members of the genera Actinomyces and Streptococcus may not be directly involved in the microbial progression, these species do appear to be essential to the construction of the network of microbial species that comprise both the subgingival plaque matrix. The temporal fluctuation (emergence/disappearance) of members of this microbiota from the developing lesion appears to depend upon the physical interaction of the periodontal pocket inhabitants, as well as the utilization of the metabolic end-products of the respective species intimately involved in the disease progression. A concerted action of the end-products of prokaryotic metabolism and the destruction of host tissues through the action of a large number of excreted proteolytic enzymes from several of these periodontopathogens contribute directly to the periodontal disease process.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of Bacteroides gingivalis in periodontal disease

The microbial flora in adult advanced periodontitis lesions is comprised of Gram-negative rods, with Bacteroides gingivalis as one of the major representatives. This review deals with biological properties of surface antigens, hemagglutinin (attachment factor), and capsular structure of B. gingivalis. Sera containing high IgG antibody levels to B. gingivalis enhanced the complement-mediated bactericidal activity in vitro, although the susceptibility to complement-mediated lysis differed among B. gingivalis strains. The protective effect of immunization against B. gingival is infection was examined in hamsters in which cotton threads had been tied to the gingival margins of the mandibular first molar. Repeated oral topical application of hyper-immune sera against B. gingivalis resulted in effective elimination of the organisms from the periodontal lesions in the experimental animals.

Biology of asaccharolytic black-pigmented Bacteroides species

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Arylaminopeptidase activities of oral bacteria

Protease and peptidase enzymes are thought to play a role in the virulence of many oral organisms, especially those associated with periodontal diseases. In order to evaluate the peptidases of periodontopathogens, we compared the arylaminopeptidase activities of Bacteroides gingivalis with those of other oral and non-oral bacteria. Sixty-three bacterial strains representing the prominent cultivable organisms in human periodontal pockets were tested, including representatives of the black-pigmented Bacteroides, Actinobacillus, Actinomyces, Campylobacter, Capnocytophaga, Eikenella, Fusobacterium, Haemophilus, Lactobacillus, Streptococcus, and Veillonella species. Each micro-organism was examined for its ability to hydrolyze 18 synthetic substrates of beta-naphthylamide derivatives of amino acids, dipeptides, and tripeptides. Quantitation of the enzyme activity was accomplished by colorimetric measurement of the amounts of released beta-naphthylamines. N-CBz-glycyl-glycyl-L-arginine-beta-naphthylamide was readily cleaved by B. gingivalis, but slightly or not at all by the other oral strains tested. L-arginine-beta-naphthylamide was cleaved by B. gingivalis, Capnocytophaga species, and Streptococcus species, but not readily by the other Bacteroides strains. Some dipeptide substrates tested, such as glycyl-L-arginine- and glycyl-L-proline-beta-naphthylamide, were strongly cleaved by B. gingivalis and weakly cleaved by other Bacteroides strains. Since high levels of N-CBz-glycyl-glycyl-L-arginyl-aminopeptidase activity are characteristic of B. gingivalis, its measurement may be valuable in the identification of this organism in clinical samples as an aid in diagnosis and monitoring of periodontal infections. Furthermore, this and other aminopeptidases produced by B. gingivalis and other oral organisms may play a role in the tissue destruction seen in periodontal disease.

Antigenic studies of oral and nonoral black-pigmented Bacteroides strains

Antigens of several oral and nonoral strains of Bacteroides asaccharolyticus (proposed classification of oral B. asaccharolyticus, Bacteroides gingivalis), Bacteroides melaninogenicus subsp. intermedius, B. melaninogenicus subsp. melaninogenicus, and B. melaninogenicus subsp. levii were identified in soluble preparations obtained by sonication, autoclaving, and NaOH treatment of whole bacterial cells. The sonicate preparations contained the most complete representation of soluble antigens using antisera to the whole organism in gel precipitation tests. Among strains of B. melaninogenicus subsp. intermedius many common antigens were detected, and no consistent antigenic differences were seen between strains from oral and nonoral sites. None of the antigens of B. melaninogenicus subsp. intermedius reacted with sera raised to several strains of oral or nonoral B. asaccharolyticus, nor did antigens prepared from the latter strains react with antisera to B. melaninogenicus subsp. intermedius. At least one common antigen was shared by strains of B. melaninogenicus subsp. intermedius and strains of B. melaninogenicus subsp. melaninogenicus; however, subspecies-specific antigens were also found. Antigens from and antisera to oral and nonoral strains of B. asaccharolyticus did not react with sera to and antigens from B. melaninogenicus subsp. melaninogenicus. Strains of B. asaccharolyticus isolated from the oral cavity were antigenically distinct from strains of B. asaccharolyticus obtained from nonoral sites and lesions. This lack of cross-reactivity between the oral and nonoral strains of B. asaccharolyticus together with recent findings of marked genetic differences between oral and nonoral strains of B. asaccharolyticus suggest that these groups of organisms may represent different species.

The influence of dental plaques on the microvasculature of the oral mucous membrane

This investigation was designed to explore the effect of plaque, obtained at different stages of accumulation, on the microvasculature of the hamster cheek pouch. Five groups of three dental students followed an oral hygiene abstinence program for 22 days. At day 2, 9, and 22, plaque was sampled from different anterior teeth, pooled and suspended in a reduced diluting fluid. Each of the three pooled plaque suspensions was then introduced into the right or left cheek pouche of five hamsters. Microvascular changes in the pouches were then observed and recorded photomicrographically until vascular reconstitution occurred. Plaque and gingival indices were taken, and the microbial composition of the plaque was determined according to gram-staining characteristics and morphology. The results indicate that the microvascular response was not a function of age and composition of plaque. This finding is based on the observation that 2-, 9-, and 22-day-old plaque induced similar microvascular damage which required approximately the same recovery period of 9 days to reconsitute normal microvascular function.

Growth of Bacteroidaceae in stirred fermentors

The conditions for increasing bacterial yields in cultures of Bacteroidaceae by the use of stirred fermentors and pH control were investigated by means of three representative species: Sphaerophorus necrophorus, Bacteroides fragilis, and B. melaninogenicus. A medium containing tryptone, yeast extract, and glucose or sucrose was used. Horse serum had to be added to obtain substantial growth of B. melaninogenicus. The optimal pH for growth rate and yield was 7.0 to 7.2. Lysis of the bacteria occurred when the glucose (or sucrose) was exhausted. The rate of lysis was very high in cultures of S. necrophorus, less so in B. fragilis and B. melaninogenicus. Pleomorphism, manifested as large sperical forms of the bacteria, was observed in the late logarithmic phase of S. necrophorus. Great differences in the length of the lag phase and of the mean generation time were found among the three bacterial species. The yield in static cultures of the three species without pH control was approximately 0.4 g of dry cells per liter, but was increased, in stirred fermentors with pH control, to 3.5 g (S. necrophorus), 2.7 g (B. fragilis), and 4.3 g (B. melaninogenicus) per liter. With an inoculum density of 5 to 10 mg (dry weight) per liter, these yields were obtained in approximately 10 (S. necrophorus), 25 (B. fragilis), and 35 hr (B. melaninogenicus), respectively.

Collagenolytic activity of bacteria

Actively growing aerobic and anaerobic bacteria were screened by a plate assay, with reconstituted guinea pig collagen as a substrate, for their ability to produce a collagenolytic factor. Collagenolytic activity was not demonstrated among the aerobic organisms tested, with the exception of one strain of Staphylococcus aureus (only when grown under anaerobic conditions). Collagenolytic activity, however, was detected in cultures of Clostridium tetani and Bacteroides species other than B. melaninogenicus. Collagenolytic activity of these organisms could be confirmed by measuring the amount of hydroxyproline liberated from the collagen gel during growth. Although collagenase production by Pseudomonas aeruginosa has been suggested in previous reports, our results were negative. An extracellular fraction of P. aeruginosa was able to hydrolyze a synthetic hexapeptide Cbz-glycyl-l-prolyl-glycyl-glycyl-l-prolyl-l- alanine, but was without detectable effect on reconstituted collagen.