Periodontal Microbiology Flashcards
What was the mode of early microbiology experiments?
What’s the issue with this?
Growing things on a plate
The problem is the “we know what we can grow” bias
What revolutionized microbiological study?
Molecular appraoaches
How many distinct oral species can be in a person?
40-60
Core microbiome
About 8% of species seen in a person’s mouth are seen in other people’s mouth
These microbiomes can change with ethnicities
The plaque biofilm definition
Organized cooperating community of organisms with specific inter-bacterial and host-bacterial interactions
T/F - you expect to see all 5 stages of biofilm formation in the mouth
False - we can brush and tongue away biofilm
What are the main species of Primary colonizers
Strep sanguis
Actinomyces viscosus
What occurs during the Attachment phase of biofilm formation?
Planktonic bacteria adhere to an acquired pelicle
What is in a pellicle t make bacteria attach to it?
Glycoproteins and antibodies
What bacterial characteristics change following attachment?
Synthesis of outer membrane proteins (this is what our body sees as foreign bodies)
Active cellular growth
What occurs during the growth stage of biofilm formation?
Co-aggregation and Co-adhesion
Co-aggregation
Cell-to-cell recognition of genetically distinct cell types
Cell clumps form and attach to a pellicle
Co-adhesion
Interactions between suspended and already adhering micro-organisms
What influences co-adhesion?
Temperature (no coadhesions below 37 C)
Lactose (more lactose means less co-adhesion)
Most of what we do to prevent caries effects what?
Co-adhesion
What occurs during biofilm maturation?
Increase in diversity
Replication and matrix formation
Ecological succession
Primary colonizers
Gram+ and Gram- streptococci that bind to pellicle proteins form saliva
Secondary colonizers
Gram- species that bind to the bridge species
Why do secondary colonizers need to bind to a bridge species?
They can’t bind to the tooth, so they have to bind to bacteria
What is known as the “bridge species”?
F. nucleatum
Tertiary colonizers
Gram- species that bind
Our body sees these as pathogens
How does the biofilm environment change when it increases in thickness?
Difficulty diffusing things in and out of the biofilm
An oxygen gradient develops
Completely anaerobic conditions emerge in the deeper layers (streps start to die, which allows pathogenic species to come in)
Reverse gradients of fermentation products develop as a result of bacterial metabolism
What provides nutrients to the supragingival plaque?
Dietary products dissolved in teh saliva
What provides nutrients to the subgingival plaque?
Periodontal tissues and blood
bacterial hydrolytic enzumes breakdown host macromolecules into peptides and amino acids
