Strains Of Actinomyces Israelii Research Articles

Pathogenicity of Actinomyces israelii and Arachnia propionica: experimental infection in guinea pigs and phagocytosis and intracellular killing by human polymorphonuclear leukocytes in vitro.

Strains of Actinomyces israelii and Arachnia propionica, isolated from clinical cases of failed endodontic therapy, were examined for: (i) their ability to survive and establish themselves in the soft connective tissue that grew into subcutaneously implanted tissue cages in guinea pigs; (ii) cell-surface hydrophobicity; and (iii) phagocytosis and killing by human polymorphonuclear leukocytes (PMNs) under aerobic and anaerobic conditions. Bacteria were inoculated into the tissue cages in guinea pigs and the cage contents were retrieved after 1, 7, 14 and 21 d for culturing and light and electron microscopy. Both bacterial species showed substantial decline in the number of bacteria by day 7 after the inoculation. Thereafter, the A. israelii strain recovered and, by day 21, had started to increase in number. Light and electron microscopy revealed the formation of typical actinomycotic colonies. A. propionica, on the other hand, continued to decline in number during the entire period of experimental infection and did not form colonies. Both strains were hydrophobic, readily phagocytosed and were efficiently killed by human PMNs under aerobic and anaerobic conditions in vitro. These results suggest that the pathogenicity of A. israelii is due to its ability to establish characteristic cohesive colonies consisting of branching filamentous organisms that are enmeshed in an extracellular matrix. It seems that the organisms existing in such colonies can collectively evade destruction and elimination by host phagocytic cells, whereas in vitro suspensions of the bacteria are easily phagocytosed and efficiently killed by PMNs. With respect to A. propionica, further investigations are necessary to understand its pathogenicity.

Binding of Actinomyces viscosus to collagen: association with the type 1 fimbrial adhesin

Treatment of hydroxyapatite (HA) with human type I or type III collagen strongly promoted adhesion of Actinomyces viscosus LY7 cells. Treatment with human type V collagen was somewhat less effective while treatment with human type IV or rat type I collagen was significantly less effective. Electron microscopic observations revealed that A. viscosus cells also attached to fibrils prepared from human type I collagen. The alpha 1 (1) polypeptide chain derived from type I collagen was ineffective in promoting binding and the alpha 2 (1) polypeptide chain exhibited moderate activity. Heat- or urea-denatured type I collagens were also ineffective in promoting binding. Mutants of A. viscosus that possess type 1 fimbriae, but not type 2 fimbriae or no fimbriae, also bound to collagen-treated HA; this suggests that the adhesin responsible was associated with type 1 fimbriae. Strains of Actinomyces israelii and Actinomyces odontolyticus also exhibited strong binding to collagen-treated HA, while Actinomyces naeslundii ATCC 12104 did not. The avidity of Actinomyces species for collagen would seem to be at least partially responsible for the high proportions of these organisms found on cemental and root tooth surfaces.

Coaggregation of oral Bacteroides species with other bacteria: central role in coaggregation bridges and competitions.

Seventy-three freshly isolated oral strains representing 10 Bacteroides spp. were tested for their ability to coaggregate with other oral gram-negative and gram-positive bacteria. None coaggregated with any of the gram-negative strains tested, which included Capnocytophaga gingivalis, C. ochracea, C. sputigena, and Actinobacillus actinomycetemcomitans. Strains of Bacteroides buccae, B. melaninogenicus, B. oralis, and B. gingivalis failed to coaggregate with any of the gram-positive strains tested. However, six Bacteroides spp. coaggregated with one or more species of gram-positive bacteria. Most isolates of B. buccalis, B. denticola, B. intermedius, B. loescheii, B. oris, and B. veroralis coaggregated with strains of Actinomyces israelii, A. viscosus, A. naeslundii, A. odontolyticus, Rothia dentocariosa, or Streptococcus sanguis. The strongest coaggregations involved B. denticola, B. loescheii, or B. oris; 22 of 25 strains coaggregated with A. israelii. Only B. loescheii interacted with certain strains of S. sanguis; these coaggregations were lactose inhibitable and were like coaggregations between A. viscosus and the same strains of S. sanguis. In fact, B. loescheii and A. viscosus were competitors for binding to S. sanguis. Many bacteroides also acted as coaggregation bridges by mediating coaggregations between two noncoaggregating cell types (e.g., S. sanguis and A. israelii). Evidence for binding-site competition and coaggregation bridging involving noncoaggregating cell types from three different genera provides support for the hypothesis that these intergeneric cell-to-cell interactions have an active role in bacterial colonization of the oral cavity.

The comparative cariogenicity and plaque-forming ability in vivo of four species of the bacterium Actinomyces in gnotobiotic rats

Gnotobiotic WAG RIJ rats on a high sucrose diet were monoinfected with 12 strains of Actinomyces spp. Moderate levels of caries were induced by a single strain of Actinomyces naeslundii and low levels by two strains of Actinomyces viscosus, three strains of A. naeslundii and one strain of Actinomyces israelii. No caries was induced by single strains of A. viscosus and A. israelii or by three Actinomyces odontolyticus strains. Only fissure caries was observed. Scanning electron microscopy showed that all strains colonized the fissures and most colonized the lingual surface of the teeth, but to a limited extent. Production of abundant and dense plaque was not always accompanied by caries.

A simple method for extracting human lymphocyte stimulants from human dental plaque bacteria of the genus actinomyces

The effect of acid concentration on the hot-acid extraction of antigens from Actinomyces viscosus that stimulate human peripheral blood lymphocytes in vitro was tested. The optimum pH for release of these antigens in a soluble low molecular-weight form was pH 2.3. Preliminary purification on Sepharose 4B demonstrated that most of the lympho-stimulatory material (about 90 per cent) had a mol. wt of about 100,000. This partially-purified antigenic material was mainly protein. The pH 2.3 hot-acid extraction was also suitable for extracting antigens that stimulate cellular immune responses from three strains of Actinomyces naeslundii and 1 strain of Actinomyces israelii, but did not release lympho-stimulatory material from Streptococcus sanguis which is a poor human peripheral-blood lymphocyte-stimulant and was used to demonstrate that the hot-acid extraction is not simply extracting a mitogenic macromolecule common to all bacteria. As good yields of soluble, biologically-active antigens were obtained from all of the Actinomyces, the procedure described will facilitate the purification and characterization of these antigens.

Coaggregation of human oral Cytophaga species and Actinomyces israelii.

A total of 19 strains of oral Cytophaga sp. obtained from subgingival plaque deposits were tested for their ability to coaggregate with strains of Actinomyces israelii, A. viscosus, A. naeslundii, Streptococcus sanguis, S. mutans, S. salivarius, and S. mitis. Coaggregation was observed only with A. israelii. Based on their coaggregation patterns with eight A. israelii strains, the Cytophaga strains were distributed among three distinct groups: those that coaggregated with A. israelii PK16 but not with A. israelii W1011 (ATCC 29322), those that coaggregated with A. israelii ATCC 29322 but not with A. israelii PK16, and those that coaggregated with none of the eight A. israelii strains. In each of the coaggregations, prior heat treatment (85 degrees C, 30 min) of the Cytophaga cells prevented coaggregation, whereas identical treatment of the A. israelii cells had no effect. The ability of A. israelii PK16 to form adherent plaque on a tooth surface previously coated with Cytophaga plaque was tested with one of the coaggregating Cytophaga strains. White patches of A. israelii plaque were found covering both the amber-colored Cytophaga plaque on the cementum surface as well as the enamel surface to which Cytophaga strains do not adhere. Electron micrographs of thin-sectioned mixed-plaque material revealed both cell types in close proximity. In addition, electron micrographs of negatively stained coaggregated cells showed interbacterial adherence between surface fimbrae on A. israelii and outer membrane blebs on the gram-negative Cytophaga sp. The kinetics of binding of A. israelii to spheroidal hydroxyapatite and to root powder were indicative of a high-affinity binding system with comparatively large numbers of available binding sites on both substrata. These results indicate the highly specific nature of Cytophaga sp.--A. israelii recognition. The contribution of such recognition toward the mechanisms that are responsible for the indigenous nature of these oral bacteria is discussed.

Growth of several strains of actinomyces israelii in chemically defined media.

PREVIOUS work from this laboratory1 has described a technique for obtaining uniform and quantitative inocula of the Gram-positive filamentous anaerobe Actinomyces israelii. It has also been shown2–4 that the medium of Howell and Pine5 could be simplified to give a chemically defined medium containing inorganic salts (including ammonium sulphate), glucose, glutathione, seven L-amino-acids (serine, cysteine, leucine, isoleucine, lysine, tryptophan and glutamic acid) and five growth factors (biotin, inositol, pyridoxal, nicotinic acid and riboflavin) which would support growth of a single strain of A. israelii in repeated serial culture. Further work6 has described some of the chemical and physical changes which occur in a series of defined media during growth of the same Wills strain of A. israelii.

The cultivation of Actinomyces israelii in a progressively less complex medium.

SUMMARY: Six strains of Actinomyces israelii were trained to grow in continued subculture on a medium composed of 99 volumes of 1 % casein hydrolysate + 1 volume of heart broth, the mixture containing 0·5 % (w/v) glucose. Poor growth of limited viability was obtained in a medium consisting of 1 % casein hydrolysate + 0·5% glucose (w/v) only. The addition of a wide variety of different amino-acids, fatty acids, growth factors and mineral salts to certain of the less complex media did not compensate for the partial or complete omission of the heart broth. Of the glucose supplied in relatively complex media about 40 % was utilized, and lactic acid equivalent to 30-60% of the glucose utilized appeared in the medium.