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Toxic properties of the cell wall of gram-positive bacteria
Abstract:
The biological activity of Odontomyces viscosus, which has been reported to cause periodontal disease in hamsters, was examined. The microorganism was cultured anaerobically in Brain Heart Infusion broth, and the cells were harvested. The washed cells were injected intradermally into the abdomen of rabbits. After 72 hr, a well-defined, firm, raised nodule (about 1.0 by 1.5 cm) with an erythematous border was seen at the injection site. Suspensions of cell wall and cytoplasmic material were injected intradermally, and the lesions appeared only at the site of cell wall injection. The cell walls, which were then treated with trypsin, pepsin, and ribonuclease, again produced the characteristic lesion. These nodular dermal lesions persisted for a minimal time of 10 days. The enzymatically treated cell walls were then hydrolyzed with 1 n HCl, and such hydrolysis up to 1 hr failed to alter the toxic activity of the cell walls. Similar dermal nodular lesions were obtained by injection of enzymatically treated cell walls of strains of Staphylococcus aureus, Streptococcus groups B, C, E, F, K, Lactobacillus casei, and Actinomyces israelii. Treatment with hot and cold trichloroacetic acid solutions and proteolytic enzymes, or with formamide, yielded insoluble fractions which produced the characteristic nodular lesions. The size of the lesion resulting from injection of these fractions was proportional to the amount of the injected material. The active fraction, which does not appear susceptible to hydrolysis by lysozyme, is thought to be cell wall mucopeptide. Histological studies showed skin abscesses due to the toxic reaction; however, in addition to the acute inflammatory reaction, there was local eosinophilia.
Insights
The toxic component causing skin lesions from Odontomyces viscosus is its cell wall mucopeptide. This finding was confirmed through various enzymatic and chemical treatments, identifying the specific bacterial component responsible for the inflammatory reaction.
Area of Science:
- Microbiology
- Immunology
- Dermatology
Background:
- Odontomyces viscosus is known to cause periodontal disease.
- The specific biological activity and toxic components of O. viscosus were not fully elucidated.
- Understanding microbial virulence factors is crucial for disease pathogenesis research.
Purpose of the Study:
- To investigate the biological activity of Odontomyces viscosus.
- To identify the specific component of O. viscosus responsible for inducing dermal lesions.
- To characterize the nature of the toxic reaction induced by O. viscosus.
Main Methods:
- Anaerobic culture of O. viscosus and isolation of cellular components (cell wall, cytoplasmic material).
- Intradermal injection of bacterial cells, cell wall, and cytoplasmic fractions into rabbits.
- Enzymatic (trypsin, pepsin, ribonuclease) and chemical (HCl, trichloroacetic acid, formamide) treatments of cell wall fractions.
- Histological examination of induced dermal lesions.
Main Results:
- Intradermal injection of O. viscosus cells and cell wall fractions induced firm, raised dermal nodules with erythematous borders.
- Cytoplasmic material did not induce lesions, indicating the cell wall as the active component.
- Enzymatic and chemical treatments yielding insoluble fractions retained the ability to induce similar nodular lesions, suggesting a stable, likely mucopeptide, component.
- Lesion size was dose-dependent.
- Histology revealed skin abscesses, acute inflammation, and local eosinophilia.
Conclusions:
- The toxic activity of Odontomyces viscosus resides in its cell wall, likely the mucopeptide component.
- This cell wall mucopeptide induces a significant inflammatory and abscess-forming reaction in rabbit skin.
- The findings contribute to understanding the pathogenesis of diseases caused by O. viscosus and similar bacteria.