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PubMed1987

In vitro caries-like lesion production by Streptococcus mutans and Actinomyces viscosus using sucrose and starch.

We investigated the formation of caries-like lesions on root and enamel sections by S. mutans and A. viscosus when grown in four different carbohydrate substrates. The substrates were: sucrose, starch + alpha-amylase, and a combination of starch and sucrose with and without alpha-amylase. Twenty-four sections with exposed windows on both the root and enamel surfaces were exposed to the individual bacterial species in each of the four substrates for three weeks. At three weeks, the sections were removed and lesion depths measured. When grown in sucrose alone, S. mutans produced significantly deeper lesions in both root and enamel surfaces when compared with A. viscosus. However, S. mutans failed to produce lesions when grown in "limited" sucrose with starch added, whereas A. viscosus in this same substrate produced lesions in the enamel and root surfaces. A viscosus also produced either similar or significantly deeper lesions in both root and enamel surfaces, when compared with S. mutans grown in the two substrates with amylase. Thus, under these in vitro conditions, it was demonstrated that A. viscosus could utilize starch, whereas utilization of starch by S. mutans was alpha-amylase-dependent.

Actinomyces↗
PubMed1989

Relative adherence of Bacteroides species and strains to Actinomyces viscosus on saliva-coated hydroxyapatite.

The study was designed to compare the adherence of several Bacteroides species to A. viscosus. Using 3H, we labeled 24 laboratory strains, including 13 Bacteroides species and 11 fresh clinical isolates of three Bacteroides species. Their adherence to A. viscosus bound to a saliva-coated mineral surface was quantified by liquid scintillation. Adherence relative to a standard strain, B. gingivalis 2561, was compared. Among the lab bacteroides, those of B. gingivalis (eight strains) were the greatest binders (mean, 80.5 +/- 12.4%). Strains of other lab bacteroides bound less well (mean, 33.4 +/- 6.3%). The difference in means was statistically significant (p less than 0.01). The mean for B. gingivalis strains was also significantly greater than that for strains of B. intermedius (51.7 +/- 6.2%). Attachment of B. gingivalis was saturable in experiments in which either input concentration or time was the independent variable, indicating that B. gingivalis cells do not accumulate in this vitro simulation of plaque formation by binding to each other. Subculture did not seem to affect the degree of binding.

Actinomyces↗
PubMed1991

Association of proteases of Porphyromonas (Bacteroides) gingivalis with its adhesion to Actinomyces viscosus.

P. gingivalis adheres to A. viscosus on mineral surfaces mimicking teeth. To study whether P. gingivalis proteases contribute to its binding, mutants of P. gingivalis deficient in proteases were compared with their parent strain and a P. gingivalis-type strain for their adherence to A. viscosus on saliva-coated hydroxyapatite by manipulating a radio-isotope binding assay. Adherence of P. gingivalis 2561 to A. viscosus was studied by tests of the effects of incubation temperature and known inhibitors or promoters of proteases. Controls were handled by the assay run in PBS buffer at 22 degrees C. Two mutants deficient in trypsin-like protease were found to be deficient in adherence (% attachment relative to control: 3.2 +/- 0.1% and 11.2 +/- 0.4%), while a collagenase-deficient mutant had an adherence score (51.6 +/- 8.4) closer to that of the parent strain (75.6 +/- 7.2%). Heating P. gingivalis at 70 degrees C decreased its subsequent adherence at 22 degrees C by 80%. Adherence decreased by 60% when the assay was run at 4 degrees C, but increased by 70% at 37 degrees C. Reducing agents (dithiothreitol, cysteine, and mercaptoethanol) enhanced P. gingivalis adherence by 50 to 60%. Protease inhibitors (BZMD, SBTI, TPCK, TLCK, CMPS, PMSF) decreased adherence by 10 to 50%. Also, Hg2+ and Zn2+ decreased adherence by 30 to 50%, and arginine decreased it by 50%. Most of these effects on P. gingivalis adherence were statistically significant (p less than 0.05). Analysis of these data suggests that P. gingivalis proteases may contribute to the cohesion of P. gingivalis and A. viscosus.

Actinomyces↗
PubMed2002

Isolation of Arcanobacterium (Actinomyces) pyogenes from cases of feline otitis externa and canine cystitis.

Arcanobacterium pyogenes is a normal inhabitant of the mucous membranes of domestic animals, such as cattle, sheep, swine, and goats. It is also an opportunistic pathogen in these animals, where it causes a variety of purulent infections involving the skin, joints, and visceral organs. Two recent cases of isolation of A. pyogenes from companion animals are reported. In the first case, a cat presented with a chronic otitis externa, from which A. pyogenes was isolated in pure culture. The second case involved a dog with a urinary tract infection, where A. pyogenes was isolated from urine as the predominant bacterial species. In both cases, the A. pyogenes isolates were presumptively identified by macrobiochemical tests, and then their identities were confirmed by polymerase chain reaction analysis and 16S rRNA gene sequencing.

Actinomyces↗
PubMed1980

Comparative ultrastructure of certain Actinomyces species, Arachnia, Bacterionema and Rothia.

A comparative ultrastructural study was carried out on several species of Acinomyces and related Gram-positive rods including Arachnia, Bacterionema, Rothia and Leptotrichia. A total of 52 well characterized strains were examined by transmission electron microscopy. Particular attention was paid to the ultrastructure of the cell periphery, that is the plasma membrane, periplasmic space, the cell wall per se and extramural structures, including surface "fuzz". In addition, the ultrastructure of various features of the cytoplasm were also examined. A good correlation appeared to exist between certain ultrastructural characteristics of the microorganisms and their taxonomic position as determined by other criteria. It should be noted, however, that the ultrastructure of certain strains differed markedly from that of the remaining strains of the species. This observation raises some doubt on the appropriateness of the current classification for these particular strains. The ultrastructural features of the cell periphery were found to be particularly stable for all strains grown under standard conditions. For this reason, ultrastructural features of the cell wall and associated structures are probably a more reliable source of morphological criteria for identification purposes than the ultrastructural characteristics of the cytoplasmic components which tend to be more variable. The results suggest that certain ultrastructural features are useful criteria for the identification and classification of these Gram-positive rods.

Actinomyces↗