Acquisition of Oral Microbiota PDF

Acquisition of oral microbiota Originally developed by: Presented by Dr Christina Adler Dr Eby Sim Faculty of Medicine and Health Faculty of Medicine and Health The University of Sydney Page 1  Learning objectives...

Acquisition of oral microbiota Originally developed by: Presented by Dr Christina Adler Dr Eby Sim Faculty of Medicine and Health Faculty of Medicine and Health The University of Sydney Page 1  Learning objectives Know stages of microbial colonisation of the oral cavity Understand factors which influence microbial colonisation of the oral cavity Know factors that may cause changes in the oral microbial composition over time Know the stages of plaque development Know the advantages & disadvantages of life within a biofilm The University of Sydney Page 2 Acquisition and colonisation of oral microbiota The University of Sydney Page 3  Development of the oral microbiome (early childhood) The University of Sydney Page 4  0 – 6 months – Womb is sterile – Transient and then Streptococcus species dominate the infant oral microbiome, which has a narrow diversity. – Impact of delivery mode – Impact of early feeding e.g. precolostrum (early milk) from mothers and their offspring’s saliva, revealing shared Streptococcus and Staphylococcus species from full genome sequencing. Ruiz, L. et al. Microbiota of human precolostrum and its potential role as a source of bacteria to the infant mouth. Sci Rep 9, 8435, doi:10.1038/s41598-019-42514-1 (2019). – The type of milk consumed appears to influence this early diversity. e.g. breast compared to formula-fed infants have higher abundances of Streptococcus and Veillonella species. The Streptococcus species are thought to increase their production of lactate due to lactose metabolism, providing a food source for Veillonella. Dzidic, M. et al. Oral microbiome development during childhood: an ecological succession influenced by postnatal factors and associated with tooth decay. ISME J 12, 2292-2306, doi:10.1038/s41396-018-0204-z (2018). The University of Sydney Page 5  6 months – Childhood – Tooth emergence – Establishment of solid foods – This provides both a non-shedding tooth surface for biofilm maturation and increased diversity of nutrients for the microbial community, which together results in an increase in the diversity of the oral microbiome, causing it to become more adult-like. – Some of the increasingly abundant bacterial taxa emerging during this period include Fusobacterium, Lactobacillus, Neissera, Gemella and Haemophillius. Sulyanto, R. M., Thompson, Z. A., Beall, C. J., Leys, E. J. & Griffen, A. L. The Predominant Oral Microbiota Is Acquired Early in an Organized Pattern. Sci Rep 9, 10550, doi:10.1038/s41598- 019-46923-0 (2019). The University of Sydney Page 6  6 months – childhood The University of Sydney Page 7  Puberty – The later childhood oral microbiome is characterized by the further enrichment and increased abundance of bacterial taxa, including periodontal disease pathogens, Porphyromonas gingivalis. – Puberty = hormones provide a nutrient source for gram negative anaerobes (P. gingivalis) Lif Holgerson, P., Esberg, A., Sjödin, A. et al. A longitudinal study of the development of the saliva microbiome in infants 2 days to 5 years compared to the microbiome in adolescents. Sci Rep 10, 9629 (2020). https://doi.org/10.1038/s41598-020-66658-7 The University of Sydney Page 8  Adulthood – Early to middle age, stable diversity and composition unless altered by major environmental stresses – Environmental stresses: diet, smoking, pregnancy psychological – Older age, decline in diversity associated with decreased salivary flow rate and increased Candida albicans Simpson CA, Adler C, du Plessis MR, et al. Oral microbiome composition, but not diversity, is associated with adolescent anxiety and depression symptoms. Physiol Behav. 2020;226:113126. The University of Sydney Page 9  Questions 1. Peak diversity in the oral microbiome is reached at which stage of life? A. Infancy (0-6 months) B. Early childhood (6 months – 2 years) C. Puberty D. Early – middle adulthood E. Older age The University of Sydney Page 10 Plaque/biofilm formation The University of Sydney Page 11  Plaque/biofilm formation The University of Sydney Page 12  Acquired pellicle – For bacteria to adhere, they require something to stick to – Salivary or acquired pellicle coats the tooth surface – Appears seconds after brushing – Contains: 100+ salivary glycoproteins, lipids, proline rich peptides, amylase, statherin (inhibits calcium phosphate precipitation) – After 2 hours, 20-80nm on lingual and 200-700nm buccal – Why thicker on buccal? The University of Sydney Page 13  Dental plaque/biofilm formation – Adhesion – Early colonisers – Later colonisers – Mature plaque The University of Sydney Page 14  Dental plaque/biofilm formation - Adhesion Bacteria to adhere – Overcome salivary forces causing aggregation of bacteria – Mechanical shearing forces Non-specific/low affinity – Ionic, hydrophobic – H-bonds – Van der Waals Specific/high affinity – Adhesins – Fimbrae, pilli e.g. Actinomyces oris uses fimbrae to attach to statherin in the salivary pellicle The University of Sydney Page 15  Dental plaque/biofilm formation – Early/Late colonisers – Commensals – Streptococci (80%): S. mitis, S. gordonni, S. sanguinis, S. oralis – Co-adhesion: bacteria in saliva to attach to bacteria on plaque – Late colonisers: Fusobacterium nucleatum, Prevotella intermedia, Haemophillius parainfluenza The University of Sydney Page 16  Dental plaque/biofilm formation – Mature plaque – Interbacterial matrix surrounds bacteria in plaque – Matrix contains bacterial and host products to make plaque sticky – Structurally/morphologically diverse: flagellated and motile forms – Elaborate structures: corn cobs, test tube brushes and a. Spirochetes hedgehogs b. Corn cobs c. Test tube brushes The University of Sydney Page 17  Dental plaque/biofilm formation – Mature plaque – Growth/metabolism dependent on nutrients – Bacteria derive nutrients from host and diet – Host = salivary glycoproteins – Diet = sugars, amino acids etc. – Increased plaque = decreased oral health – Gingivitis = inflammation of epithelial and connective tissue around teeth, without loss of connective tissue attachment or Bowen, W. et al. “Oral Biofilms: Pathogens, Matrix, and Polymicrobial alveolar bone loss Interactions in Microenvironments.” Trends in microbiology 26 3 (2018): 229-242. The University of Sydney Page 18  Dental plaque/biofilm formation – Mature plaque The University of Sydney Page 19  Dental calculus – Calcified dental plaque – Calcium phosphate mineral salts form between and within viable microbes – People with elevated salivary calcium levels form calculus quicker – Biofilm layer covering the calculus – Inhibition of calculus formation: pyrophosphates, zinc salts, polyphospphonates The University of Sydney Page 20  Mucosal microbiota – Epithelium: gingival, buccal and palatal – Desquatmate – Lower volume of microbiota than on teeth – Buccal: P. gingivalis – Tongue contain papillae, providing protected sites for bacterial colonistaion – Tongue: S. mitis and S. salivarius, medically compromised Candida albicans. The University of Sydney Page 21  Biofilm Dental plaque is a biofilm A biofilm is a polymer encased community of microbes that accumulate at a surface As the biofilm matures it becomes more complex The biofilm is organised to distribute nutrients and protect itself against the host Activity of the biofilm reflects the activity of the whole microbial community The University of Sydney Page 22  Advantages to living in a biofilm Advantage Mechanism Examples Antimicrobial Bacteria in biofilms grow slowly Oral biofilms are resistant resistance and can exclude Abs via to Beta-lactam Abs (e.g. bacterial exopolysacchardides penicillin), which target growing cells Food sharing Bacteria in biofilms develop Streptococci produce lactic food webs, by-products of acid which is then certain bacteria are food catabolised by Veionella sources for others. species Communication Quorum sensing, which is the cell S. gordonni carbohydrate density dependent regulation of metabolism gene expression. Controls virulence, Ab roduction, motility. Competence Exchange of DNA between S. mutans exchange DNA to bacteria enable these bacteria to tolerate acidic conditions The University of Sydney Page 23  Disadvantages to living in a biofilm Disadvantage Mechanism Examples Slow diffusion Due to structure, this can limit Lactic acid metabolism by restricting Hydrogen peroxide (H202) nutrients and allowing build-up of by-products Concentrating Difficulty in removing substances Fluoride chemicals can lead to build up in heavy metals Bacteriocins Protein toxins, narrow activity S. salivarius major producer and work on similar bacteria of bacteriocins that reduce URT infections (S. pneumonia), potential probiotic The University of Sydney Page 24  Questions 1. Which of the following is a common early coloniser in dental plaque? A. Porphymonas gingivalis B. Streptococci C. Fusobacterium nucleatum 2. Is the following statement true or false: The physiology of the oral biofilm reflects the activity of the entire microbial community A. True B. False The University of Sydney Page 25 Review The University of Sydney Page 26  Oral Microbiology Lectures 1. Introduction to microbes – classes of microbes, Koch’s principles 2. Bacterial morphology and nomenclature – morphology, gram +ve/-ve phylogenetic tree, naming 3. Bacterial metabolism – aerobic/anerobic respiration, simple sugars first, growth curve in lab and in mouth 4. Host microbe interaction – commensals, gut, mouth, skin, respiratory microbiomes 5. Pathogens – stages of infection, adherence, transmission, virulence, opportunistic 6. Acquisition of oral flora – stages of life, influence of birth, teeth, foods, hormones, stress The University of Sydney Page 27