Biofilms Flashcards
What is a biofilm?
Matrix-enclosed bacterial or fungal populations adherent to each other and/or to surfaces or interfaces
What are the 4 defining characteristics of a biofilm?
- Provides defence
- Favourable habitat
- Community
- Default mode
What are the stages in biofilm development in teeth?
- Planktonic cell: free floating bacteria. Very susceptible to antimicrobials
- Free floating planktonic cell attaches to the enamel. Forms a micro colony.
- Mature biofilms forms
What are the benefits to bacteria of being a biofilm?
- Protective environment
- Co-ordinated cellular events: bacteria can release SCFAs to “talk” to each other
- Division of labour
- EPS (extra polymeric substances) traps nutrients
- Less energy utilised
- Survival in numbers
What are the 3 requirements for biofilm formation?
- Microorganism
- Surface
- Conditioning film
What is glycocalyx?
- Slime - Composed of extrapolymeric substrate (EPS)
- Maintains a hydrated environment
- Microcolonies are organised within the glycocalyx, allows active diffusion
- Helps to maintain ‘tissue like’ integrity
- Provides a protective barrier ( against immune factors and antibiotics)
What is dental plaque?
A diverse microbial colony (predominantly bacteria) found on the tooth surface, embedded in a matrix of polymers of bacterial and salivary origin
What is the MAIN aetiologic agent associated with caries and periodontal disease?
Plaque
What type of infection is a root canal infection?
Endodontic infection
What are some examples of oral mucosal infections?
- Thrush
- Angular cheilitis
- Denture stomatitis
What is the main determinant for microbe colonisation in the oral cavity?
Saliva
What are the stages of plaque formation?
- Pellicle formation
- Pioneer bacteria colonisation
- Microcolonies and extracellular polysaccharides
- Biofilm development
- Mature plaque
Which bacteria are the ‘pioneers’ in plaque development?
Streptococcus oralis, Streptococcus mitis, Streptococcus sanguis
Describe the main stages in plaque formation listed below:
- Pioneer colonisation
- Outgrowth
- Secondary colonisation
- Climax community
- Pioneer colonisation: Streptococcus oralis, streptococcus mitis, streptococcus sanguis.
- Outgrowth: microcolony spread outwards and upwards.
- Secondary colonisation: pioneers act as a substrate, co-aggregation, specific interactions.
- Climax community: polysaccharide production, synergistic metabolic interactons, nutrients, redox potential, oxygen, pH
What type of environment do streptococcus mutant thrive in?
Acidic
What is glucose transferase (GTF)?
An extracellular enzyme synthesised by streptococcus mutans and streptococcus sanguis. GTF is responsible for the synthesis of extracellular polysaccharides (EPS).
What is glucan binding protein (GBP)?
Proteins produced by Streptococcus mutans. Play a role in virulence and in maintaining biofilm structure.
Describe the effect on the oral microbiome if an individual has a high protein diet
- Few acidogenic organisms-> ammonia produced
- More Gram negatives
- Secondary metabolites - malodour
Describe the effect on the oral microbiome is an individual has a diet high in carbohydrates
- Metabolism reduces pH
- Aciduric organisms thrive
- Streptococci and lactobacilli
Define ‘aciduric’
Thriving in an acidic environment
Define ‘acidogenic’
Acid producing
