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Flashcards in Biofilms and Plaque Deck (34)
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1

What is a Biofilm?
¡A ____ of microbes adhering to ____ ____ and a ___ ____, and encased in a sticky ____________.


¡A community of microbes adhering to each other and a solid surface, and encased in a sticky exo-polysaccharide (EPS) matrix.

2

Where do they form?

____
____
____


¡Non-shedding, fluid coated surface, in a non-sterile environment----> Biofilm
 

3

Why do we care?


¡Helpful biofilms 

  • §
  • §
  • §

¡Harmful

  • ____ ____
  • §Medicine and Dentistry
    • ▪___ infections
    • ▪Difficult to _______
       


¡Helpful biofilms 
§Natural process of decay
§Composting
§Bioremediation of toxic waste
¡Harmful
§Industrial Biofouling
§Medicine and Dentistry
▪Chronic infections
▪Difficult to remove from surfaces
 

4

How do biofilms form?


¡1-Initial adhesion
¡2-Stable adhesion
¡3-Growth,co-aggregation, matrix (EPS) production
¡4-Mature biofilm (climax community)
 

5

Adhesion is a major factor in biofilm formation
¡Initial adhesion
____ ____, _____ binding,
§_____ to a surface
§_____ bonds
___ ___ ___forces
§
§
 


¡Initial adhesion
§Non-specific, reversible binding,
§Attraction to a surface
§Hydrogen bonds
§Van der Waals forces
§
§
 

6


¡Stable adhesion
____ bonds
____ bonds
____ bonds
¡Usually mediated by bacterial ___ ___--> _____
§Adhesins recognize surface molecules on the___ ___-->  _____
§Provides ___ and ____
§
 


¡Stable adhesion
§Covalent bonds
§Ionic bonds
§Hydrophobic bonds
¡Usually mediated by bacterial surface proteins- Adhesins
§Adhesins recognize surface molecules on the binding target - Receptors
§Provides specificity and permanency§
§
 

7

Adhesin - Receptor Interactions

___ ____

___ ___ (____)

___ ___ ____

____  ___ (____)


¡Protein-Protein
¡Protein-Carbohydrate (lectins)
¡Carbohydrate - Protein- Carbohydrate
¡Other combinations (lipids)
 

8

9

Bacterial Adhesins


¡_____-___ ____ ____ ___
_____-____ that bind ___
___ ____ ____ - Gram ___ outer membrane, ______
_____ _____- ____
 


¡Fimbriae-hair like surface appendages
¡Lectins -proteins that bind sugars
¡Lipo-teichoic acid - Gram + outer membrane, glycolipid
¡Extracellular polymers- capsule
 

10

Host receptors

 

  • ____ ____ on ___ cells
  • ____
    • §____
    • §____
    • §____
  • ____
    • ____
    • ____
  • ____
     


¡Sialic acid on mucosal cells
¡Pellicle
§Proteins
§Carbohydrates
§Lipids
¡Minerals
§Calcium
§Phosphate
¡Glycoproteins
 

11

Tooth Pellicle

12

Colonization of surfaces


¡Some bacteria ___ ____ __ ____
CALLED ____
Process____
Adhere to ___,  ____ ___
§
¡Other bacteria adhere to ____ ____
§____
_____
§You might see these terms used inter-changeably
 


¡Some bacteria adhere well to surfaces
§Pioneers
§Adhesion
§(Pellicle, soft tissues)
§
¡Other bacteria adhere to pioneer bacteria
§Co-aggregation
§Co-adhesion
§You might see these terms used inter-changeably
 

13

Co-aggregation

14

Visual coaggregation scores for different pairs of strains. 

Visual coaggregation scores for different pairs of strains. Cells were grown to stationary phase and harvested after 36, 71, or 144 h. Sphingomonas sp. strain 2.10 and Afipia sp. strain 2.2 (36 h) showed a score of 0 (no coaggregation), P. marcusii 2.21 and B. natatoria 2.3 (72 h) showed a score of 1+, Sphingomonas sp. strain 2.18 and Afipia sp. strain 2.2 (144 h) showed a score of 2+, B. natatoria 2.1 and Nocardioides sp. strain 2.20 (144 h) showed a score of 3+, and B. natatoria 2.1 with M. luteus 2.13 (72 h) showed a score of 4+. Bar, 1 cm.

15

Corncob and Bristle-brush

16

How do biofilms form III


¡Growth-microcolonies form community
¡Matrix synthesis (EPS)
 

17

Growth

Dental plaque. Coloured scanning electron micrograph (SEM) of a fracture through a tooth showing dental plaque (top) and dentin (bottom). Plaque consists of a film of bacteria embedded in a glycoprotein matrix. The matrix is formed from bacterial secretions and saliva. Plaque is the main cause of tooth decay. The bacteria feed on sugars in food, producing acid as a waste product. This acid corrodes the teeth's enamel coating, resulting in dental caries. A build-up of dental plaque can also lead to inflamed and infected gums. Severe gum disease can lead to teeth falling out. Dentin is mineralised connective tissue, that makes up the majority of the tooth. Magnification: x350 when printed at 10 centimetres wide.

18

Exopolysaccharide (EPS)


___ ___, or “____”
¡Secreted by biofilm bacteria to form a___,____ layer around bacteria
¡Made of ____ ____, allows ____
¡Exact composition ______
¡
 


¡Biofilm matrix, or “slime”
¡Secreted by biofilm bacteria to form a cohesive, protective layer around bacteria
¡Made of polysaccharide gel, allows diffusion
¡Exact composition varies depending on bacteria present
¡
 

19

20

The EPS Matrix

21

Mature Biofilm Structure


____ is key to survival of bacteria in biofilms
 


¡Diffusion is key to survival of bacteria in biofilms
 

22

Properties of a Biofilm

23

Affects of Structure on Biofilm
 Species with ___ ____ can live together

 Species with different requirements can live together

24

How do Mature Biofilm Communities Interact?

 

  • __ ___-
    • bacteria cooperate in the____ of ____
  • ____-
    • _____,____
  • ____
    • ____, ____
  • ___ ___
    • share ____ ____ genes
  • ____ ____-
    • bacterial _____

¡
¡
¡
 


¡Food webs-bacteria cooperate in the breakdown of nutrients
¡Protection-exopolysaccharide, metabolism
¡Antagonism-bacteriocins, pH
¡Gene transfer-share antibiotic resistance genes
¡Quorum sensing-bacterial coordination
¡
¡
¡
 

25

26

Beneficial Nutritional Interactions in Plaque

Step and Actinomyces break down sugar to lactate

Veillonella in same vicinnity of strep because it eats lactate

27

Protection

Biolfilm Protects against

____
____
____
____
____ ____

Bacteriophage

Phagocytes

Antibodies

Desication

Toxic Molecules

28

Five Mechanisms of Increased Biofilm Tolerance to Antimicrobials

Antimicrobial Depletion

Slow penetration

Stress Response

Altered Microenvironment

Persisters

 

29

Antagonism


¡Antagonism-the production of compounds to ____ __ ____of other organisms
____
____ ___
____-small ____ that ___ __ ___in the ____ of other bacteria
§Streptococcus mutans
▪produces ___, to lower ___ to ___
▪Produces ____ that kill other Streptococcus spp.
 


¡Antagonism-the production of compounds to inhibit the growth of other organisms
§Acids
§Hydrogen peroxide
§Bacteriocins-small proteins that poke a hole in the membrane of other bacteria
§Streptococcus mutans
▪produces acids, to lower pH to ~5.5
▪Produces bacteriocins that kill other Streptococcus spp.
 

30

Gene Exchange

 

  • ¡Different bacteria in close contact may ___ ____
  • ___ ____
    • ▪_____. share ____resistance genes in biofilms
  • ____ ___
  • §What are the three forms of DNA exchange between bacteria?
     


¡Different bacteria in close contact may share DNA
§Antibiotic resistance-
▪Prevotella spp. share tetracycline resistance genes in biofilms
§Metabolic capabilities
§What are the three forms of DNA exchange between bacteria?