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Oral Microbial Ecology Cheat Sheet by

Oral Ecosys­tem:

- Specific microbial species demons­trating tropism for specific tissues
- Microbial intera­ction with each other as well as with the oral enviro­nment

Form­ation of an Ecosys­tem:

Indigenous Microb­iota:
Most numerous, Compatible with host
Supple­mental Microb­iota:
Potent­ially pathog­enic, Can become invasive
Transient Microb­iota:
Don't have mechanisms for persisting in the host

Oral Ecosys­tems:

Buccal epithe­lium:
Gram-p­ositive cocci
Lingual epithe­lium:
Gram-p­ositive filaments
Suprag­ingival tooth surface:
Faculative G+ rods and cocci
Subgin­gival tooth surface:
Anaerobic G- rods and cocci



-Bathed in saliva
-Facul­atively anaerobic
-Increased mechanical disruption (swall­owing, abrasion)

-Bathed in crevicular fluid
-Reduced mechanical disruption (anatomy of gingival sulcus)

Envi­ron­mental Factors:

Oxygen tension:
pO2, partial pressure of oxygen, mmHg
Redox Potential:
Eh, tendency to acquire electrons and thus be reduced, mV
controlled by exogenous materials carboh­ydrate fermen­tation buffering capacity of plaque and saliva
Availa­bility of Nutrients:
carboh­ydr­ates, amino acids (salivary glycop­rot­eins), hemin (plasma)

Host Fluids:

Nutrients from saliva and GCF
Interferes with coloni­sation
Aggreg­ation and removal
Inacti­vation of glycolytic enzymes - death
Binds iron limiting bacterial growth
Degrades bacterial peptid­oglycan
Host Suscep­tib­ility:
- Geographic location
- Ethnicity and culture
- Diet
- Health and social status

Micr­obial Factors:

- Contact: proximity
- Dose: quantity of bacteria
- Frequency of exposure (eg newborns)
- Absorp­tion: initial reversible associ­ation with oral tissues
- Ability to accumulate at entry site
- Adaption
- Resist host defenses
- Compet­ition from other species
- Changing enviro­nments


Different species, or different strains of a single species, have distinct sets of coaggr­egation partners
Strept­ococcus spp. and Actino­myces spp., two of initial colonizing general on enamel surfaces
Fusoba­cba­cteria coaggr­egate w/ other human oral bacteria
Veillo­nella spp., Capnoc­yto­phaga spp. bind to strept­ococci/ actino­myces
Each coaggr­egation is mediated by one or more comple­mentary sets of adhesi­n-r­eceptor pairs


CoAggr­egation Compet­ition:
- Compet­ition occurs when multiple cell types recognize the same coggre­gation indicator mediator on the common coaggr­egation partner

Ecol­ogical Succes­sion:

Process by whereby a microbial population undergoes a continuous series of changes in compos­ition as different species colonise and become establ­ished at the expense of others.
As conditions change, the dominant m/o's will either adapt and be retained or will be superseded by a new species better equipped to survive the altered enviro­nment.


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