Anaerobic Cocci: Proteolytic Bacteria and Enamel Protectors
The anaerobic cocci group in the oral microbiocenosis is represented predominantly by Peptostreptococcus and Veillonella species. These microorganisms differ fundamentally in their type of metabolism and clinical significance.
Peptostreptococci include species such as Peptostreptococcus asaccharolyticus and P. stomatis. Their preferred habitat is the gingival sulcus. They are characterized by a pronounced proteolytic type of metabolism. This means that peptostreptococci actively break down peptones and various amino acids to obtain energy, whereas their effect on carbohydrates is extremely weak.
Veillonella species (Veillonella) perform an entirely different function. As gram-negative anaerobes and permanent residents of the oral cavity, they actively participate in dental plaque formation. However, their key feature is a potent anti-cariogenic effect.
The mechanism of this protection is based on the unique biochemistry of Veillonella:
- They do not ferment sugars directly, but instead utilize the acidic products of carbohydrate metabolism produced by other bacteria (lactic acid, pyruvate, acetate).
- Veillonella utilize these aggressive acids, converting them into completely safe water and carbon dioxide.
- As a result of this process, the environmental acidity rapidly decreases, preventing the demineralization of tooth enamel.
Lactobacilli: Bacteria with a Dual Role
Rod-shaped bacteria in the oral cavity are represented by various Lactobacillus species, among which Lactobacillus acidophilus, L. brevis, and L. fermentum are the most significant. In dental microbiology, it is customary to highlight the paradoxical dual role of these microorganisms.
- Protective function. Lactobacilli are a crucial component of colonization resistance. They physically block receptors on the surface of mucosal epithelial cells, preventing foreign agents from attaching, and exhibit pronounced microbial antagonism toward pathogenic flora.
- Pathogenic function. Possessing the ability to actively ferment carbohydrates, lactobacilli produce massive amounts of lactic acid. This local acidification of the environment is the triggering factor in the development of dental caries.
Strict Anaerobes and Periodontal Pathology
Among the microflora responsible for periodontal disease development, strict anaerobes occupy a leading position. This group includes Bacteroides (Bacteroides fragilis), Prevotella (Prevotella melaninogenica), and Porphyromonas (Porphyromonas gingivalis).
The energy metabolism of these bacteria is based on the breakdown of glucose, resulting in the formation of a complex mixture of various organic acids. From a clinical perspective, it is important to understand that these bacteria (especially P. melaninogenica) are constantly present in the gingival pockets of adult patients. This entire group of microorganisms is recognized as the main causative agents of destructive periodontal diseases.
Fusobacteria, Spirochetes, and Actinomycetes
The autochthonous (resident) microflora includes fusobacteria, such as Fusobacterium periodontium and F. nucleatum. Biochemically, they differ by synthesizing butyric and lactic acids from glucose and peptones. Their most important feature is a tendency to form stable microbial associations, most commonly with spirochetes.
Spirochetes (specifically Treponema denticola and T. vincentii) localize deep within the gingival pockets. Their main clinical danger lies in pathogenic synergism. Combining their aggression factors with fusobacteria and bacteroides, treponemes cause a severe dental condition: necrotizing ulcerative gingivostomatitis (Vincent's infection).
Additionally, actinomycetes (species Actinomyces viscosus, A. naeslundii) and Aggregatibacter species (Aggregatibacter spp.) are constantly present in this biotope. The latter colonize the oral mucosa, taking a direct part in the formation of soft dental plaque and hard dental calculus. Working in association with other microbes, Aggregatibacter significantly accelerate the development of both dental caries and periodontal inflammation.