34 - Microbial interactions Flashcards
Oral Eubiosis
Microbial balance within the oral cavity
Oral Microflora
- Can be resident/transient
- Acquired from saliva, food + H20
It can also cause various diseases:
- abscesses
- dental caries
- gingivitis
- periodontal diseases
Interactions
- Interspecies collaboration
- Interspecies competition
- Interspecies communication
- Collaborative invasion
- Bacterial co-aggregation
- Microbial relationship
Interspecies collaboration
Some anaerobic species such as P.gingivalis need a co-aggregation to survive in the presence of oxygen
Interspecies competition
Many oral species produce substances that kill closely related competitors
eg. Wild type S.mutans
Interspecies communication
Bacteria sense other species based on their characteristics
Eg. Streptococci ferment CHO + excrete lactic acid ⇢ Veillonella uses lactic acid for nutrition
Collaborative invasion
F.nucleatum invades epithelial cells but S.Cristatus cannot
After co-aggregation ⇢ S.Cristatus is carried inside by F.nucleatum
Bacterial co-aggregation
Process that helps in development + maintenance of mixed-species biofilm communities
Microbial relationship
Complex of relations between microbial species:
- Neutral ⇢ between 2 species that live together without affecting the other
- Synergy ⇢ Between 2 species living together + both mutually favoured
- Antagonism ⇢ Between 2 microbes living together + yielding inhibition of their function
Bacterial plaque
Subgingival plaque
- G- only
- In tooth’s sulcus
Subgingival plaque
- On approximal, occlusal + cervical surfaces
- Main species ⇢ Facultative anaerobes (S. Actinomyces) + G- (Veillonella, Haemophilus)
!!!Note!!!
Oral microflora varies between people
Biofilm
- Initiated by bacterial adhesion to surface
- Occurs when bacteria attaches to surface + excretes exopolymer
- Exopolymer ⇢ imbeds bacteria + attracts other microbes to newly formed microfilm
Oral plaque = main biofilm in mouth
- Attracts high concentration of bacteria
- Leading to oral diseases
