3 - Biofilm 2: Periodontal disease Flashcards
What influences oral microflora?
- host factors (systemic disease, antibiotics, hygiene)
- diet (composition, frequency)
- saliva (flow rate, pH, antimicrobial factors)
- GCF (antimicrobial)
- microbial interactions (competition, symbiosis)
- gaseous environment
What do bacteria release that increase the rate of progression towards periodontal disease?
- cytotoxins
- proteinases
- LPS
Describe the development of the biofilm related to periodontal disease.
- naked surface
- conditioning film (host salivary glycoproteins)
- linking film (streptococcus)
- co-aggregation and re-conditioning film (actinomyces)
- accumulation and shedding, eg the spread of disease (fusobacterium)
What are the key microorganisms present in a healthy periodontium?
- oral streptococci (gram positive)
- actinomyces
- veillonella
- haemophilus
- neisseri
- fusobacterium
What are the key microorganisms present in a gingivitis?
- actinomyces
- prevotella intermedia
- bacteroides
- fusobacterium nucleatum
What are the key microorganisms present in a diseased periodontium?
- prophyromonas gingivalis *
- tannerella forsythia*
- treponema denticola *
- prevotella intermedia
- A. a
Describe microbial competition.
- dominance of a biofilm
- metabolic products can toxic to other species (acids or oxidants)
- bacteriocins
- receptor antagonism
Describe microbial cooperation.
- integration and symbiosis of bacteria in the biofilm
- metabolic products that support other bacteria (saccharides, peptides, growth factors)
- adhesion substrates allow biofilm to form
- immune avoidance
What is a commensal community?
A biofilm present in a healthy mouth that avoids disease by constraining pathogens or excluding them (ie preventing adhesion)
What properties make P. ging a keystone pathogen for periodontitis?
- host cell tissue adhesion via fimbriae
- multiple proteases (collagenase, fibrinolysin, phospholipase A, phosphatases)
- endotoxin (LPS)
- capsular polysaccharide that has outer membrane vesicles
- by-products that are toxic to tissues (hydrogen sulphide, ammonia, fatty acids)
Describe the adhesion of P. ging.
- fibrillar adhesions help to invade membranes of host cells
- long fimbriae are the initial attachment
- short fimbriae which allows cell to cell aggregation and allows formation of microcolonies
What is gingipains?
- protease
- manipulates the biofilm and host defences
- causes degradation of innate receptors and cytokines
- causes tissue destruction via MMPs
- uses subversion by tricking the host system
What are the properties of A. a that make it a key stone pathogen?
- produces leukotoxin, cytotoxin and LPS
- has membrane vesicles
- has fimbriae for attachment
- can subvert host immune system
- has a glycoprotein matrix
