Microbiology Of PD Flashcards
What was Koch’s experiment?
He showed that if you have one mouse that is disease and one that is healthy you can isolate bacteria from these animals. He took blood colonies. To fulfill postulates, he purified the bacterium found in the ill animal. This purified bacteria culture infects the healthy organism, proof that this bacterium has cause a specific illness.
What are the factors involved in the development of periodontal disease?
Gingival and periodontal tissues
Bacteria
Host inflammation and immune rsponse
What is the main change from healthy tooth to periodontitis?
Pocket depth grows. Can become very deep and become anaerobic. Also causes attachment loss from the tooth.
What factors occur during periodontal disease?
Increase in biomass of bacteria (new and old) forming a biofilm esp in periodontal pockets
Change in composition of bacteria
Inflammation increasing
Immune system response to this
What happens with inflammation in periodontal disease?
More inflammation leads to more bleeding, leading to more iron available for bacteria to thrive and grow more, heightening the immune response, causing more inflammation and cycling out of control
Why is there difficulty in defining periodontal pathogens?
Sample taking is hard since periodontitis might not occur in whole oral cavity
Anaerobic species are difficult to cultivate in a lab
There are multiple perio-associated diseases that have slight difference in different subjects
What occurred in socransky et al?
Collected subgingival plaque from periodontitis patients
Used DNA:DNA hybridisation to identify them
If same bacterium present in multiple volunteers the gene would hybridise and emit a fluorescent signal
Results from socransky et all
5 major complexes found
3 (yellow, purple and green) associated with healthy flora
Orange associated with gingivitis
Red associated with periodontits
What are the 3 bacteria in the red complex?
P. gingivalis
T. forsythia
T. denticola
What are the main bacteria in the orange complex?
P. intermedia
P. micra
F. nucleatum
What is F. nucleatum?
Bridging organisms since they form a bridge between bacteria that are part of the healthy flora and the bacteria of the late complex/late colonisers
Relationship between pocket depth and bacteria?
As pocket depth increases, you get more orange and red bacteria
Relationship between bacteria and bleeding on probing?
In patients with more bleeding on probing, there are higher amounts of orange and red bacteria
How does AA survive by its virulence factors?
Leukotoxin - attacks neutrophils and leads to apoptosis
Cytolethal distending toxin which attacks T cells leading to their death
