Indigenous Oral Bacteria Research Articles

Bacteriocin activity of the bacterium Bacterionema matruchotii isolated from dental plaque in man

Production of bacteriocin by five strains of Bacterionema matruchotii isolated from dental plaque was confirmed. It was detected in the culture supernatant and inhibited the growth of various species of oral indigenous bacteria. The bacteriocin adsorbed only to sensitive cells.

病原細菌から口腔細菌へ

病原細菌から口腔細菌へ

Production, purification, and properties of a bacteriocin from Staphylococcus aureus isolated from saliva.

Staphylococci from samples of human saliva were isolated on staphylococcal-selective agar plates. These strains were tested for the inhibition of the growth of Staphylococcus aureus FDA209P. The frequency of inhibitory strains among all of the staphylococcal isolates was 5.2%. Strain IYS2, which formed the biggest inhibitory zone against the growth of the indicator strain, was used as the producer of bacteriocin. IYS2 was identified to be S. aureus, based on its biological properties. The bacteriocin was purified by sequential procedures, including ammonium sulfate precipitation, fractionation with ethanol, ion-exchange chromatography, and gel filtration. Its molecular weight was determined to be 5,000. The isoelectric point was 10.0. In amino acid composition, lysine, histidine, aspartic acid, valine, and phenylalanine were predominant. The bacteriocin was heat stable but inactivated by proteases or peptidase. The bacteriocin had a bactericidal effect on susceptible cells. An analysis of the inhibitory spectrum among typical oral indigenous bacteria showed that Streptococcus salivarius, Propionibacterium acnes, Corynebacterium parvulum, and Actinomyces israelii were susceptible to the bacteriocin. Streptococcus mutans, Streptococcus sanguis, Streptococcus mitis, Actinomyces viscosus, Actinomyces naeslundii, Fusobacterium nucleatum, Bacterionema matruchotii, and Bacteroides melaninogenicus were resistant. The majority of S. aureus tested were susceptible, and all Staphylococcus epidermidis strains tested were resistant.

Influence of combinations of oral bacteria on periapical tissues of monkeys.

The present study deals with the ability of 11 bacterial strains, in various combinations, to induce periapical reactions. The indigenous oral bacteria were originally isolated from an experimental apical periodontitis in monkey. Eight of the strains were complete collection isolated from one root canal. These strains were inoculated together, in equal proportions, into 12 root canals. In addition, 63 canals were inoculated with other combination or separate strains. At the end of the experimental period it was found that in the mixed infections the Bacteroides oralis strain predominated in most root canals. In contrast, this Bacteroides strain was not reisolated in any of nine root canals when inoculated in a pure culture. Enterococci, however, survived as pure cultures in all canals. The mixed infections showed the greatest capacity of inducing apical periodontitis, as revealed by radiography, and most pronounced was the "eight-strain collection". The facultatively anaerobic streptococci induced only weak periapical reactions.

Influence on periapical tissues of indigenous oral bacteria and necrotic pulp tissue in monkeys.

In nine monkeys (Macaca fascicularis) the pulps of 78 teeth were aseptically necrotized. Twenty-six of the pulp chambers were kept bacteria-free by sealing, while 52 were infected by the indigenous oral flora. The results were recorded clinically, radiographically and microbiologically at the beginning of the experiment and after 6-7 months. The final examination also included histologic recordings. The initially noninfected root canals were all sterile at the final samplings, indicating that the risk of contamination (including hematogenous) of root canals of this animal is very slight. It was shown that noninfected necrotic pulp tissue did not induce inflammatory reactions in the apical tissues. By contrast, teeth with infected pulp tissue showed inflammatory reactions clinically (12/52 teeth) and radiographically (47/52 teeth). Facultatively anaerobic streptococci, coliform rods and obligately anaerobic bacterial strains were most frequently found. In the final samples the number of obligately anaerobic strains increased. Some microorganisms which were isolated in the initial samples were not detected in the final samples. All infected teeth histologically examined showed strong inflammatory reactions in the periapical region.

Nitrate-reducing Activity of Human Saliva

We examined by statistical analysis the possible role of indigenous oral bacteria in nitrite formation in human saliva.In 13 volunteers' saliva, a relatively high positive correlation was observed between the nitrate-reducing activity of the saliva and the number of nitrate-reducing bacteria. However, there was no significant correlation between the nitrate-reducing activity of saliva and the concentration of salivary nitrite.The geometric mean rates (95% confidence limits of the mean) of nitrate reduction and of nitrite production of the saliva in vitro were only 0.94 (0.48-1.85)μg/ml/min and 0.37 (0.20-0.67)μg/ml/min, respectively. The estimated nitrate-reducing activity of indigenous oral bacteria in saliva thus does not support the hypothesis that the nitratereducing bacteria play an essential role in the formation of nitrite in the mouth.

The production of haemorrhagic necrosis in the hamster cheek pouch by bacterial endotoxins and catecholamines

THE demonstration of endotoxin activity in a number of indigenous oral bacteria (MERGENHAGEN, HAMPP and SCHERP, 1961) as well as the abundance of such organisms in the gingival crevice area (GIBBONS et al., 1963), suggest a possible role of endotoxin in the etiology of periodontal disease (SCHERP, 1962). Susceptibility of oral tissues to experimental pathological phenomena utilizing endotoxins has been demonstrated (Rrzzo and MERGENHAGEN, 1960). An experimental lesion employing endotoxins and catecholamines has been described by THOMAS (1956). Thomas reported that administration of epinephrine or norepinephrine locally in conjunction with either a systemic or local injection of small quantities of endotoxin produced haemorrhagic necrosis at the local site within 24 hr. The present study was undertaken to determine if this endotoxin-catecholamine lesion could be produced in oral tissues. Intraperitoneal administration of bacterial lipopolysaccharide was followed by local injection of catecholamines into the abdominal skin and cheek pouch of adult male golden hamsters. These bacterial endotoxins (Escherichia coli 0111 :B4, Bacto Lipopolysaccharide, Difco Laboratories, and Leptotrichiu buccalis, kindly supplied by Dr. Wilson de Araujo, Faculdade National de Odontologia, Rio de Janeiro, Brasil) which had been extracted by the phenol-water method, were suspended in 0.1 ml sterile pyrogen free saline and used for inoculations. Animals were anaesthetized by means of intraperitoneal injections of sodium pentobartitol for all intra-oral procedures. In order to test the necrotizing ability of each vasopressor, various concentrations of crystalline epinephrine (L-Adrenalin, Eastman Organic Chemicals) from 1000 pg/O*O5 ml to @Ol pg/O*O5 ml and norepinephrine (t_-Arterenol Bitartrate, General Biochemicals) from 100 pg/O*O5 ml to 0.01 pg/O*O5 ml dissolved in saline at constant volume were assayed for their ability to produce macroscopically visible alterations when injected submucosally in the pouch and intradermally in the skin. Such tested animals received l-3 hr previously 0.1 ml of saline intraperitoneally as a control for subsequent experiments. Epinephrine (1.0 pg) and norepinephrine (0.1 pg) did not