Microflora of Dental Plaque and other oral sites Flashcards
What is colonisation resistance
This is the function of the normal flora that acts to exclude pathogens from it and so protects the host
What are opportunistic pathogens
These can become pathogenic and attack the host under certain circumstances when the resistance of the host is reduced
Describe the features of the teeth that allow it to be a microbial habitat
- Only body site with hard, non shedding surfaces for colonisation
- Allows accumulation of a lot of bacteria and their extracellular products (plaque)
What sites on a tooth are good for bacteria to accumulate on
Approximal plaque - between the teeth
Fissure plaque in the crevices between cusps
Gingival crevice plaque
Why are the approximal areas and gingival crevice regions able to support a more diverse microbial community
These areas provide protection from adverse conditions and both are anaerobic, gingival crevice bathed in gingival crevicular fluid
Why can the smooth surfaces of teeth only be colonised by a limited number of adapted bacterial species
These surfaces are more exposed to environmental forces
How are pits and fissures on teeth adapted to allow colonisation by bacteria
these offer protection from the environment and are associated with the largest microbial communities
What is a habitat for micro-organisms on the dorsum of the tongue
papillary surfaces - fungi, filiform and foliate papillae
How is the tongue crypt adapted for microbial growth (i think this is the space below the tongue)
These crypts have a low redox potential and may acts as a reservoir for some of the gram negative anaerobes implicated in periodontal disease
What variables of saliva can influence caries susceptibility
Flow and ion content of the saliva
What are the major organic constituents of saliva
Proteins and glycoproteins (e.g. mucin)
What is the role of glycoproteins in the saliva
Glycoproteins influence aggregation and adhesion of bacteria to oral surfaces, interact with other salivary components and immune defences and act as a primary source of nutrients for normal microflora
What is the role of urea and free amino acids in the saliva
Metabolism of these and other peptides can lead to pH rise , that helps to counteract acid production after intake of carbohydrates
How do serum components reach the mouth
via the GCF - gingival crevicular fluid through the junctional epithelium of the gingiva
How can the GCF affect the ecology of the mouth
GCF flow can physically remove non-adherent microbial cells and act as a nutrient source for micro-organisms
What is the role of lysozymes in saliva
Lysozyme in saliva hydrolyses peptidoglycan in bacterial cell walls.
What does lactoferrin do in the mouth
This a glycoprotein that has a high affinity to iron
What is the role of the salivary peroxidase system
Generates inhibitors of bacterial glycolysis
Name a type of antimicrobial peptides
Histidine rich proteins
What acts as a barrier to penetrating antigens in the oral mucosa
Intra-epithelial lymphocytes
Langerhans cells
IgA
What does secretory IgA do in the mouth
Agglutinates bacteria
Modulates enzyme activity
Inhibits adherence of bacteria to buccal epithelium and enamel
What components of the immune system does GCF contain
IgF, IgM, IgA, complement and neutrophils
What are some of the most common cultivable organisms in the adult oral cavity
Gram positive facultative cocci:
- Streptococci
- Staphylococci
Gram negative anaerobic rods
Where can you find the streptococcus bacteria in the mouth
At all sites
What can many streptococci bacteria produce
Extracellular polysaccharides that are associated with plaque formation
Where are mutans streptococci regularly isolated from
From dental plaque but has low prevalence on sound enamel
What are mutans streptococci a common aetiology of
Enamel caries in children and young adults
Root surface caries in the elderly
Nursing caries in infants
What are the streptococcus salivarius group involved in
More in health than disease
What are the 2 types of streptococcus salivarius and where are they mainly isolated from
S. salivarius - Common isolate from most areas esp. mucosal surfaces
S. vestibularis - isolated mainly from the vestibular mucosa of the mouth
What are the streptococcus milleri group involved in
Opportunistic infections
Name some types of streptococcus milleri and where are these isolated from
S. constellatus, S. intermedius and S. anginosus
- Readily isolated from dental plaque and mucosal surfaces
What are the streptococcus orals group mainly involved in
Opportunistic infections
Name some types of streptococcus oralis and where are the frequently isolated from
S. sanguinis
S. gordonii
Isolated frequently from infective endocarditis
Where can other streptococci like peptostreptococcus be isolated from
Dental plaque esp. in advanced periodontitis, carious dentin, infected pulp chambers and root canals, and dental abscesses
Name an enterococcus bacteria and where they are usually isolated from
E. Faecalis
Often involved in root canal infections
Where are staphylococci often found
On the skin
Where are gram positive rods and filaments commonly isolated from
Dental plaque
What can a facultative bacteria do
Grow in aerobic and anaerobic conditions
Where can actinomyces be found most commonly
In the plaque microflora and esp. at approximal sites and can colonise gingival crevice
What is actinomycosis
When A. Israelii acts as an opportunistic pathogen and the organism can transfer from the plaque and sets up an infection elsewhere in the body
What kind of bacteria are eubacterium
These are gram positive rods that are obligate anaerobes
Where are eubacterium mostly found
In the sub gingival plaque esp. in periodontitis
Often isolated from infections head, neck and lungs as well
What kind of bacteria are lactobacillus
Gram positive rods?
Name the main feature of the lactobacillus bacteria
Very acidogenic organisms
What kind of bacteria are propionibacterium
Obligate anaerobes - gram positive
What kind of bacteria are neisseria
Aerobic gram negative cocci - early colonisers of a clean tooth surface
What kind of bacteria are veillonella
Strict anaerobic gram negative cocci
Where are veillonella mostly found
Most surfaces in mouth and found most commonly in dental plaque
What do veillonella use as energy sources
They don’t metabolise carbohydrates and utilise intermediary metabolites like lactate
What does saccharolytic mean
Involving the hydrolysis of sugars
What are porphyromonas bacteria mainly involved in
chronic adult periodontitis
What is a virulent bacteria
Produces lots of potent enzymes and toxins
Name some organisms that are very involved in chronic periodontitis
- Porphyromonas Gingivalis
- Prevotella spp.
Name some black pigmented gram negative rods
Porphyromonas spp.
Prevotella spp
Name some types of prevotella bacteria and where they are isolate from
P. intermedia
P. denticola
Isolated from dental plaque esp. sub-gingival sites
What are gram negative rods prevotella associated with
Periodontal disease and abscesses.
What type of bacteria is fusobacterium
Gram negative rods that are asaccharolytic
Where are fusobacterium found in dental plaque and what is it associated with
It is a bridging bacteria between colonisers and later adhesives
Associated with gingivitis and periodontitis
What kind of bacteria are spirochaetes
Anaerobic gram negative rods
What are spirochaetes associated with
periodontal disease
What makes up the largest portion of the oral fungal flora
Candida albicans
How common is C.albicans fungi
About 50% of the population
What are some of the viruses that can be present in the oral cavity
Herpes simplex (type 1) - most common
Cytomegalovirus
Hepatitis B/C and HIV
Coxsackie virus and papilloma
