Role of the Oral Microflora in Health

Microbial Ecology in Health and Disease 07/2009; 12(3):130-137. DOI: 10.1080/089106000750051800


The mouth contains both distinct mucosal (lips, cheek, tongue, palate) and, uniquely, non-shedding surfaces (teeth) for microbial colonisation. Each surface harbours a diverse but characteristic microflora, the composition and metabolism of which is dictated by the biological properties of each site. The resident oral microflora develops in an orderly manner via waves of microbial succession (both autogenic and allogenic). Pioneer species (many of which are sIgA protease-producing streptococci) colonise saliva-coated surfaces through specific stereo-chemical, adhesin-receptor interactions. The metabolism of these organisms modifies local environmental conditions, facilitating subsequent attachment and growth by later, and more fastidious, colonisers. Eventually, a stable biofilm community develops, that plays an active role in (a) the normal development of the physiology of the habitat, and (b) the innate host defences (colonisation resistance). Thus, when considering treatment options, clinicians should be aware of the need to maintain the beneficial properties of the resident oral microflora.

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    • "The tongue community in healthy subjects has previously been found to comprise mostly Streptococcus spp., Veillonella spp., and Actinomyces spp. [31, 32]. A recent study looking into the unculturable microbiota of the tongue has also identified the above genera, along with a Lysobacter-type species as the predominant organism found on the tongue [33]. "
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    ABSTRACT: Gingivitis is a preventable disease characterised by inflammation of the gums due to the buildup of a microbial biofilm at the gingival margin. It is implicated as a precursor to periodontitis, a much more serious problem which includes associated bone loss. Unfortunately, due to poor oral hygiene among the general population, gingivitis is prevalent and results in high treatment costs. Consequently, the option of treating gingivitis using functional foods, which promote oral health, is an attractive one. Medicinal mushrooms, including shiitake, have long been known for their immune system boosting as well as antimicrobial effects; however, they have not been employed in the treatment of oral disease. In the current study, the effectiveness of shiitake mushroom extract was compared to that of the active component in the leading gingivitis mouthwash, containing chlorhexidine, in an artificial mouth model (constant depth film fermenter). The total bacterial numbers as well as numbers of eight key taxa in the oral community were investigated over time using multiplex qPCR. The results indicated that shiitake mushroom extract lowered the numbers of some pathogenic taxa without affecting the taxa associated with health, unlike chlorhexidine which has a limited effect on all taxa.
    BioMed Research International 09/2011; 2011(1):507908. DOI:10.1155/2011/507908 · 2.71 Impact Factor
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    • "Some bacteria are harmless in the natural environment , but could become a threat in an immunocompromised animal (Higgins, 2000). Normal bacterial flora are necessary for a healthy existence and contribute by occupying a niche and controlling overgrowth of potentially pathogenic species that could result in infection and disease (Marsh, 2000; Iwase et al., 2010). For instance, Iwase et al. (2010) found that Staphylococcus epidermidis, a common nasal colonizer, can inhibit the growth and proliferation of S. aureus, a potential pathogen, in humans. "
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    ABSTRACT: Infectious disease is a growing concern for the overall declining Hawaiian monk seal (HMS) (Monachus schauinslandi) population. Recently, the HMS population in the main Hawaiian Islands (MHI) is increasing, and this may result in additional rehabilitation and release events. A key aspect for population health assessment is to identify the "normal" bacteria flora (e. g., the upper respiratory tract). Our current knowledge for the HMS flora is based on microbial isolates from stranding or mortality events rather than on healthy animals. This 14-mo study includes 52 oral and 55 nasal sampling events from the two healthy resident HMSs at the Waikiki Aquarium in Honolulu, Hawaii. Extensive culturing, Gram stains, phenotypic (e. g., biochemical), and genotypic (16S rRNA sequencing) characterization were used to identify aerobic microorganisms from the upper respiratory tract. The study detected 30 species of Gram negative bacteria, 18 species of Gram positive bacteria, and two species of yeast. The "normality" of the bacterial population was established over the study time period by consistent recovery of identical bacterial species from upper respiratory tract samplings. These results may provide a baseline for normal aerobic bacterial flora in these seals. These results may also allow for comparison to other HMSs in facilities and their wild conspecifics, and have implications for diagnosis of infection in diseased animals.
    Aquatic Mammals 04/2011; 37(3):377-385. DOI:10.1578/AM.37.3.2011.377 · 1.02 Impact Factor
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    • "While the majority of them are normal/commensal bacteria, some of them are opportunistic pathogens responsible for the development of oral microbial infectious diseases such as dental caries and periodontitis [3]. Saliva as an oral circulating fluid is heavily laden with bacteria (108 – 109 cfu/mL) [4]. These salivary bacteria reflect the oral microbiota composition and could serve as an indicator of the health and disease status of oral cavity. "
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    ABSTRACT: Human saliva can be separated by centrifugation into cell pellet and cell-free supernatant, which are called cellular phase and liquid phase in this study. While it is well documented that the cellular phase of saliva contains hundreds of oral bacteria species, little is known whether the liquid phase of saliva contains any information related to oral microbiota. In this study, we analyzed the bacterial nucleic acid contents of the liquid phase of saliva. Using primers universal to most eubacterial 16S rDNA, we detected large amounts of bacterial 16S rRNA and rDNA in the cell-free phase of saliva. Random sequencing analysis of forty PCR amplicons from the cell-free phase of saliva led to 15 operational taxonomic unit (OTU) groups. Furthermore, using denaturing gradient gel electrophoresis (DGGE), we compared 16S rRNA/rDNA profiles derived from liquid phases and cellular phases of saliva samples, and found positive correlations (Pearson Correlation=0.822, P<0.001) between these sample groups. These findings indicate that the liquid phase of saliva contains numerous bacterial 16S rRNA/rDNA molecules that have correlations with bacteria existing in the cellular phase.
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