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BDS3: BAMS > Biofilms > Flashcards

Biofilms Flashcards

1
Q

What is a biofilm?

A

A matrix enclosed microbial population adherent to each other and/or to surfaces or interfaces

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2
Q

What factors influence biofilm development & adherence?

A

Host - mucosal surface, pellicle, minerals, lectins
Saliva - mechanical washing, buffering, bactericidal enzymes
Bacterial - adhesins, LTA, proteases & virulence factors

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3
Q

Name some orally relevant biofilms.

A 
Plaque
Calculus
Mucosal Infections
Sutures
Dentures
Handpieces
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4
Q

What four things are required for caries to occur?

A

Tooth
Sugar
Bacteria
Time

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5
Q

What oral environmental factors contribute to caries devolopment?

A 
Plaque pH
Chewing gum
Fluoride 
Sealants
Saliva - buffer capacity, flow rate, composition
Protein
Sugars - clearance rate, frequency
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6
Q

What are the key pathogens involved in caries?

A

Streptococcus mutants (gram +ve cocci forming chains)
Lactobacillus acidophilus (produce lactic acid, dissolving enamel)
Actinomyces viscosus
Nocardia spp.

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7
Q

What are the 6 stages of caries progression?

A 
Adhesion - of organism to tooth surface
Survival & growth
Biofilm formation
Complex plaque
Acid - starts to erode the enamel
Caries
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8
Q

What type of bacteria is strep. Mutans?

A

Gram positive coccus

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9
Q

What is the action of streptococcus mutans?

A

Adhesion and biofilm formation
Metabolises dietary sucrose to form insoluble polymers of glucose (stick to surfaces)
Survive in low pH environments - enamel dissolution

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10
Q

What is the virulence of s. Mutans?

A

Combined virulence - adhesion, glucans & acid

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11
Q

Name some virulence factors.

A

Adhesins
Binding proteins
Sugar modifying enzymes (fructanase, dextranase)
Polysaccharides - protection (matrix) & storage (glycogen)
Acid tolerance & adaptation (ATPase)

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12
Q

What are the properties of water soluble glucans?

A

Readily degraded by the cells for energy source

Formation of lactic acid

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13
Q

What are the properties of water insoluble glucans?

A

Sticky and hard - act as cement
Promote accumulation of plaque
Very difficult to remove by toothbrushing

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14
Q

What pH level does demineralisation occur at?

A

When pH drops below 5.5

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15
Q

What is the pH of lactic acid?

A

pH 3.5

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16
Q

What are the anti caries effects of fluoride?

A

Systemic - ingested fluoride encourages developing enamel as fluorapatite which reduces its solubility in acid and promotes remineralisation
Topical - converts surface layer of enamel to fluorapatite
Antimicrobial - inhibits plaque metabolism, activity increases at pH values

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17
Q

What are the methods of preventing dental caries?

A

Reduce carbohydrate in saliva - dietary change
Increase tooth resistance to attack - fluoride
Reduce tooth susceptibility - fissure sealants
Reduce or eliminate cariogenic micro-organisms - anti-microbial agents e.g. Inhibitors, probiotics, immunisation, vaccination
Mechanical disruption of biofilms - toothbrushing, scaling

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18
Q

What four key factors account for streptococcus mutans success in causing caries?

A

Sucrose metabolism
Adhesins
Polysaccharides
Low pH

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19
Q

What is sucrose converted into to help S. Mutans persist? And how is it converted?

A

Glucans

Glucosyl-transferase

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20
Q

How does S. Mutans adapt to its acidic environment?

A

ATPase
Altered cell membrane
Protection/repair mechanisms

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21
Q

What strategies are there for control of S. Mutans?

A 
Probiotics
Vaccination
Inhibitors
Immunisation
Fluoride
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22
Q

What are the 5 types of oral biofilm diseases?

A 
Caries
Endodontic infection
Periodontal infections (gingivitis, periodontitis)
Oral malodour
Mucosal infections (thrush, angular cheilitis, denture stomatitis)
23
Q

What different factors influence the oral micro flora?

A 
Host factors e.g. Systemic disease, OH
Diet - consistency, frequency of intake
Saliva - flow rate, pH balance, antimicrobial factors
Gingival crevicular fluid
Microbial interactions
Gaseous environment
24
Q

What are the different classifications of periodontal disease?

A

Gingivitis
Periodontitis
Necrotising periodontal disease
Peri-implantitis

25
Q

What host factors contribute to development of periodontal disease?

A 
Smoking/tobacco use
Genetics
Pregnancy/puberty
Systemic disease e.g. Diabetes
Nutrition e.g. High protein diets
26
Q

Commensal bacteria are usually gram-________ __________

A

Gram-positive aerobic

27
Q

What pathogenic microorganisms are found in periodontitis?

A 
Porphyromonas gingivalis
Tannerella forsythia
Treponema denticola 
Prevotella intermedia
A.a
28
Q

What type of bacteria is porphyromonas gingivalis?

A

Gram-negative non-motile rod

Strict anaerobe

29
Q

What are the key virulence factors of porphyromonas gingivalis?

A

Host cell tissue adhesion and invasion (fimbriae)
Elaboration of proteases
Endotoxin (LPS)
Capsular polysaccharide & outer membrane vesicles
Tissue toxicity metabolic by-products

30
Q

How do fimbriae aid in adhesion of bacteria to host cells?

A

Help invade membrane vesicle of host cells by binding to cellular integrins.
Can be long (FimA) or short (Mfa1)

31
Q

What is the action of gingipains?

A

Degradation of innate receptors
Degradation of cytokines e.g. IL-8, ICAM-1
Thereby down regulates the host response in the form of reduced inflammation.

32
Q

What is gingipain?

A

A protease secreted by porphyromonas gingivalis

33
Q

What dental pathology is a. Actinomycetemcomitans seen in?

A

Localised aggressive periodontitis

Some chronic periodontitis

34
Q

What are the virulence factors of A.A.?

A 
Host tissue cell adherence & invasion
Elaboration of leukotoxin
Degradative enzymes
Endotoxin 
Bone resorption-inducing factor
35
Q

What are the systemic implications of periodontal disease?

A

Destructive inflammation locally & systemically
Increased cardiovascular disease risk (1.2-3.9x)
Suggested increased risk in RA
Increased risk of diabetes (6x)

36
Q

What clinical management is available for periodontal disease?

A 
Mechanical disruption - toothbrushing, scaling
Chemotherapeutic - Periostat
Probiotics
Vaccines - ineffective
Surgery - last resort
37
Q

What patient groups are susceptible to developing Candidal infections?

A 
Pregnant
Age - elderly, infancy
Cellular immunodeficiency - AIDS, leukaemia, aplastic anaemia
Diabetes
IV drug addiction
Malnutrition
38
Q

What are the classifications of oral candidosis?

A 
Pseudomembranous - thrush
Erythematous - atrophic, denture related
Hyperplastic - candidal leukoplakia
Angular cheilitis
Generalised candidosis with oral manifestations
39
Q

What are the different grades of denture induced stomatitis?

A

Newton’s type I - localised inflammation
Newton’s type II - diffuse inflammation
Newton’s type III - granular inflammation

40
Q

What are the signs & symptoms of denture induced stomatitis?

A

Inflamed mucosa - particularly under upper denture
Burning sensation
Discomfort
Bad taste

41
Q

Name some candida species.

A

Candida albicans
Candida glabrata
Candida parapsilosis
Candida tropicalis

42
Q

What part of Candida albicans allows it to adhere to surfaces?

A

Hyphae - penetrate & invade cells

43
Q

What is a hydrolytic enzyme?

A

An enzyme that catalyses the hydrolysis of a substrate through the addition of water.

44
Q

Name three hydrolytic enzymes.

A

Phospholipase
Haemolysin
Proteinase

45
Q

How is oral candidosis diagnosed?

A 
Smear
Oral rinse
Swab
Foam pad
Biopsy (candida leukoplakia only)
46
Q

What antifungal therapy is available for treating candida?

A 
Echinocandins e.g. Micafungin
Azoles e.g. Fluconazole 
Polyenes e.g. Nystatin
Chlorhexidine
Novel antifungal compounds e.g. Tea tree oil
47
Q

What is the difference between Candida albicans & candida glabrata?

A

Glabrata does not respond to treatment with azoles
Glabrata doesn’t have hyphae so biofilm is not as strong
Albicans does respond to treatment with azoles
Albicans have hyphae

48
Q

What’s the difference between candidosis & candidiasis?

A

There is no difference. They are interchangeable terms.

49
Q

What guidelines should you give to patients wearing complete dentures to reduce the chance of microbial infection?

A

Daily removal of denture plaque.
Maintain reduced levels of denture plaque - clean with soak & non abrasive brush.
Only used denture cleansers extra-orally & always rinse thoroughly afterwards.
Annual cleaning of denture by dental professional (ultrasonic cleanser).
Do not soak >10mins in sodium hypochlorite solutions.
Denture adhesives minimise instability and prevent unwanted particles.
Do not wear the denture continuously.
Seek an annual professional evaluation for oral health.

50
Q

What species of candida is insensitive to azoles?

A

Candida glabrata

51
Q

What are echinocandins?

A

Antifungals
Fungicidal effect
Only IV administration
Expensive

52
Q

What are azoles?

A

Antifungals

Completely ineffective against biofilms

53
Q

What are polyenes?

A

Antifungals
Fungicidal action
Embed their cells in the cell membrane causing it to rupture

BDS3: BAMS (2 decks)

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