100-to-one. Many of these organisms have not as yet been successfully cultured, branded, or otherwise differentiated and identified. Organisms expected to be found in the human microbiome, however, may be generally categorized as bacteria (which comprise the majority), members of domain Archaea (single celled organisms similar to but distinguished from bacteria), yeasts, and single-celled eukaryotes as well as various parasitic worms and viruses, the latter include viruses (of the RNA or DNA sub-types) that infect the cellular microbiome organisms (e.g., bacteriophages, the viruses of bacteria).anaerobes in particular bacteroides; the latter group represents bacteria that do better in the absence of oxygen. The oral cavity of the new-born baby is devoid of bacteria but rapidly becomes colonized with bacteria such as Streptococcus salivarius. With the appearance of the teeth during the first year of post-uterine life, colonization by Streptococcus mutans and Streptococcus sanguis occurs and these organisms take up residents on the dental surface and gingiva (gums). Other strains of oral streptococci adhere strongly to the gums and cheeks but not to the teeth. The gingival crevice area (supporting structures of the teeth) provides a habitat for a variety of anaerobic species; those that prefer oxygen deprived surroundings. Bacteroides and spirochetes colonize the mouth around puberty. The levels of oral spirochetes are elevated in patients with periodontal diseases. Among this group, Treponema denticola is the most studied and is considered as one of the main causes of periodontitis and gingivitis. Treponema denticola is proteolytic (protein digesting) bacterium.Porphyromonas gingivalis is a Gram-negative oral anaerobe strongly associated with chronic adult periodontitis (pyorrhea); once known colloquially as “trench mouth.” Dental plaque (a biofilm that adheres to the teeth and requires regular visits to a dentist for cleaning) consists of bacterial cells (mainly S. mutans and S. sanguis), salivary polymers and bacterial extracellular products. These accumulations of microorganisms subject the teeth and gingival tissues to high concentrations of bacterial metabolites which results in dental disease. If not taken care of, via brushing or flossing, the plaque can turn into tartar (its hardened form) and lead to gingivitis or periodontal disease.

As an example of the variety of those microorganisms currently hitching a ride in one of several particular portions of our body we need only look inside the mouth. Oral bacteria include streptococci, lactobacilli, staphylococci, corynebacteria, and various

Having learned about the veritable “zoo” of microorganisms living in the mouth the reader may now understand why physicians consider the mouth the dirtiest cavity in the human body and why a human bite can be such as serious injury.

Sunday, April 19, 2009, 04:19 PM