Acquisition of Oral Microflora (Oral microbiology) Flashcards
List stages of microbial colonization
1) Vertical transmission -> Mother to baby
2) acquisition and colonization
3) Pioneer species -> First set of species
4) Microbial succession
5) Increasing species diversity
6) environmental modification -> go back to microbial succession
7) Climax community -> Once flora community has reached a relatively constant community
Describe streptococci in Oral Cavity:
- First group to appear (pioneer species)
- Found in all mouth sites
- Produce extracellular polysaccharides (plaque)
List the four groups of streptococci:
- Mitis group
- Salivarius group
- Mutans group
- Anginosus group
Describe mitis group
Most common group; opportunistic; first bacteria to attach to pellicle
Describe salivarious group
Prefers mucosal sites
Describe mutans group
Found on hard surfaces; linked with caries
Describe anginosus group
Found in plaque and mucosal sites; associated with distant infections (e.g. endocarditis)
Describe microbial succession
Pioneer species modify local environment -> allows colonization by other species.
Describe autogenic succession (environmental modification)
Changes by microflora community
- pH
- Lower Oxygen
- Cryptitopes -> proteases partially destroy receptors
- Nutrient generation
- Inhibition of other organisms
Describe allogenic succession (environmental modification)
External changes
- Tooth eruption
- Antimicrobial agents
- Dentures
Describe fastidious organisms in microbial succession and give an example
“Fussier” organisms that need specific nutrients and environment.
e.g. Fusobacterium nucleatum
Microbial succession in tooth eruption and periodontal disease
Tooth eruption and periodontal disease allow new bacteria to enter.
Red-complex -> Three bacteria common in periodontal disease
1) Porphyromonas gingivalis
2) Tannerella forsythia
3) T. Denticola
pH tolerance of cariogenic bacteria and give examples
Cariogenic bacteria are acid tolerant (e.g. S. mutans and lactobacilli)
- supragingival bacteria metabolize sugars into acid
pH tolerance of periodontal disease bacteria
Periodontal disease bacteria are basic tolerant.
- Subgingival bacteria metabolize proteins (blood and gingiva) into nitrogen products which are basic
List stages of plaque/biofilm formation
- Acquire pellicle
- Reversible attachment
- Adhesin-receptor attachment
- Coadhesion
- Biofilm formation
- Detachment
Describe ‘acquire pellicle’
Salivary protein coating covers surface.
- Acquired seconds after brushing
- Proteins and fragments from saliva attach to tooth surface
- Thinner on lingual side due to tongue
Describe ‘reversible attachment’
Bacteria reversibly bind to wrong receptors
Describe ‘adhesin-receptor attachment’
Bacteria strongly bind with receptors on pellicle. Glycans are produced.
Describe ‘coadhesion’
New bacteria bind to first bacteria and glycans
Describe ‘Biofilm formation’
Bacteria produce more glycans to form biofilm; more bacteria bind and replicate
Describe ‘detachment’
Parts of biofilm detach
Describe ‘plaque formation’
- Pioneer species colonize pellicle (Streptococci bacteria - Mitis group esp.)
- Plaque matrix produced of carbohydrate polymers (Glucans and fructans)
- Coaggregation of other of bacteria bind to pioneer species (Actinomyces, Haemophilus, and Neisseria species)
- Fusobacterium nucleatum aggregate wide range of bacteria: Form bridge between early and late colonizers
- Obligate anaerobes bind as oxygen levels fall
Describe ‘life in biofilm advantages’
- Plaque is food storage
- Lower oxygen
- Coadhesions
- Quorum sensing -> Environment sensing
- Enzyme sharing
- Gene transfer
- Resistance to antimicrobial substances
- Resistance to host immune
what is calculus?
Mineral deposition within the dental plaque due to mineral precipitation from saliva.
