Oral Microbial Ecology Cheat Sheet

A cheat sheet in English by Carmilaa
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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

Microe­nvi­ron­ments:

Suprag­ing­ival:

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

-Bathed in crevicular fluid
-Anaerobic
-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
pH:
controlled by exogenous materials carboh­ydrate fermen­tation buffering capacity of plaque and saliva
Temper­ature:
variations
Availa­bility of Nutrients:
carboh­ydr­ates, amino acids (salivary glycop­rot­eins), hemin (plasma)

Host Fluids:

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

Microbial Factors:

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

Co-Agg­reg­ation:

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:

**Coaggregation:**
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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