MFD 27 (PD) Flashcards
Periodontal disease
Describe the process of carrying out a checkerboard-DNA, DNA- hybridisation format
- extract DNA from samples
- attach to DNA probes to wells on plate , parallel to each other
- label DNA from samples
- Apply multiple clinical samples perpendicular to DNA probes at 90 degree angle
- Observe signal of probe (thus results are semi-quantitative)
Why is checkerboard-DNA, DNA- hybridisation format useful in identifying cause of periodontal diseasw?
2) How many species can you look at at a time
3) What do we use now?
can screen huge numbers of bacteria, thus can loo for association between disease and bacteria as well as grouping bacteria which appear together into complexes.
2) 40
3) sequence everything with next generation sequecning
What are the red complex species of periodontal disease?
Porphymonas gingivalis
Tanella forsythia
T .denticola
What sort of bacteria bind to fusobacterium nucleatum, the bridging bacteria between early colonisers (streptococcus) and later colonisers?
later colonises are more pathogenic
and include red complex bacteria e.g. p.gingivalis
T.forsythia
Treponomea denticola
What do all red complex bacteria have in common?
they are all gram-negative, proteolytic, anaerobes
P.gingivalis
1) What shape is it?
2) What sort of pigment does it produce?
3) What can it adhere to?
4) What agar should be used to identify it?
1) rod
2) black and brown porphyrin (haem-containing pigements)
3) I am assuming fusobacterium nucleatum as well as certain forms of streptococci, therefore don’t really need the bridging organism
4) blood agar
T.forsythia
1) shape?
2) is it a challenge to grow in the lab?
3) how does one wild type of it hide itself from the immune system?
1) short rods with tapered ends
2) difficult to grow in a monoculture, growth is facilitated by other bacteria
3) has a glycosylated S-layer on the outside
T. denticola
1) Which phylum is it apart of?
2) what is the name of the bacterium it is related to ? What disease this bacterium cause
3) How does it adhere?
4) Are they motile?
1) spirochaetes (they have distinctive double membranes)
2) Treponemea pallidum, (causes syphilis)
3) in outer sheath have a major protein
4) have a flagellum, yes
TM7 phylum has recently now able to be cultured. How did they do it?
they enriched a plaque sample,
continuously using flourscent insitu hybridisation to see which sample had the phylum then , carryied on enriching till the got a pure culture.
What is the significance of TM7 phylum in dentistry?
2) what shape are they?
is present in mild periodontitis compared with health or severe disease
2) variance, rod or cocci depending on partner bacterium species it grows with
WHy is it important that we can grow bacteria in pure cultire?
to carry out koch’s postulates
How big is the genome of TM7 genome?
2) What is the significance of this?
3) How was the genome identified?
1) less than 1Mbp
2) very small , reflects how bacteria is dependent on other species as could not be grown alone , had o be co-cultured with A. odontolycitus
3) via reconstruction of meta-genomic sequence
What animals are used in animal models for perio?
2) which is the most difficult to work with?
3) Which are the most similiar to humans?
1) rodents, dogs, primates
2) primates
3) primates
Co-infection in animal models leads to greater damadge than with any of the bacteria alone, the bacteria being: P.ging and F.nucleatum
true
Why are animal models not useful the way koch intended in periodontal disease?
as perio is likely due to more than one bacterium and its more to do with level than the infecting bacterium that is important
