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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
What host factors contribute to development of periodontal disease?
``` Smoking/tobacco use Genetics Pregnancy/puberty Systemic disease e.g. Diabetes Nutrition e.g. High protein diets ```
26
Commensal bacteria are usually gram-________ __________
Gram-positive aerobic
27
What pathogenic microorganisms are found in periodontitis?
``` Porphyromonas gingivalis Tannerella forsythia Treponema denticola Prevotella intermedia A.a ```
28
What type of bacteria is porphyromonas gingivalis?
Gram-negative non-motile rod | Strict anaerobe
29
What are the key virulence factors of porphyromonas gingivalis?
Host cell tissue adhesion and invasion (fimbriae) Elaboration of proteases Endotoxin (LPS) Capsular polysaccharide & outer membrane vesicles Tissue toxicity metabolic by-products
30
How do fimbriae aid in adhesion of bacteria to host cells?
Help invade membrane vesicle of host cells by binding to cellular integrins. Can be long (FimA) or short (Mfa1)
31
What is the action of gingipains?
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
What is gingipain?
A protease secreted by porphyromonas gingivalis
33
What dental pathology is a. Actinomycetemcomitans seen in?
Localised aggressive periodontitis | Some chronic periodontitis
34
What are the virulence factors of A.A.?
``` Host tissue cell adherence & invasion Elaboration of leukotoxin Degradative enzymes Endotoxin Bone resorption-inducing factor ```
35
What are the systemic implications of periodontal disease?
Destructive inflammation locally & systemically Increased cardiovascular disease risk (1.2-3.9x) Suggested increased risk in RA Increased risk of diabetes (6x)
36
What clinical management is available for periodontal disease?
``` Mechanical disruption - toothbrushing, scaling Chemotherapeutic - Periostat Probiotics Vaccines - ineffective Surgery - last resort ```
37
What patient groups are susceptible to developing Candidal infections?
``` Pregnant Age - elderly, infancy Cellular immunodeficiency - AIDS, leukaemia, aplastic anaemia Diabetes IV drug addiction Malnutrition ```
38
What are the classifications of oral candidosis?
``` Pseudomembranous - thrush Erythematous - atrophic, denture related Hyperplastic - candidal leukoplakia Angular cheilitis Generalised candidosis with oral manifestations ```
39
What are the different grades of denture induced stomatitis?
Newton's type I - localised inflammation Newton's type II - diffuse inflammation Newton's type III - granular inflammation
40
What are the signs & symptoms of denture induced stomatitis?
Inflamed mucosa - particularly under upper denture Burning sensation Discomfort Bad taste
41
Name some candida species.
Candida albicans Candida glabrata Candida parapsilosis Candida tropicalis
42
What part of Candida albicans allows it to adhere to surfaces?
Hyphae - penetrate & invade cells
43
What is a hydrolytic enzyme?
An enzyme that catalyses the hydrolysis of a substrate through the addition of water.
44
Name three hydrolytic enzymes.
Phospholipase Haemolysin Proteinase
45
How is oral candidosis diagnosed?
``` Smear Oral rinse Swab Foam pad Biopsy (candida leukoplakia only) ```
46
What antifungal therapy is available for treating candida?
``` Echinocandins e.g. Micafungin Azoles e.g. Fluconazole Polyenes e.g. Nystatin Chlorhexidine Novel antifungal compounds e.g. Tea tree oil ```
47
What is the difference between Candida albicans & candida glabrata?
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
What's the difference between candidosis & candidiasis?
There is no difference. They are interchangeable terms.
49
What guidelines should you give to patients wearing complete dentures to reduce the chance of microbial infection?
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
What species of candida is insensitive to azoles?
Candida glabrata
51
What are echinocandins?
Antifungals Fungicidal effect Only IV administration Expensive
52
What are azoles?
Antifungals | Completely ineffective against biofilms
53
What are polyenes?
Antifungals Fungicidal action Embed their cells in the cell membrane causing it to rupture

BDS3: BAMS (2 decks)

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