Biofilms and Plaque

Question 1

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

Answer 1

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

Question 2

Where do they form?

____
____
____

Answer 2

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

Question 3

Why do we care?

¡Helpful biofilms

• §
• §
• §

¡Harmful

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

Answer 3

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

Question 4

How do biofilms form?

Answer 4

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

Question 5

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

Answer 5

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

Question 6

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

Answer 6

¡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§
§

Question 7

Adhesin - Receptor Interactions

___ ____

___ ___ (____)

___ ___ ____

____ ___ (____)

Answer 7

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

Question 9

Bacterial Adhesins

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

Answer 9

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

Question 10

Host receptors

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

Answer 10

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

Question 11

Tooth Pellicle

Question 12

Colonization of surfaces

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

Answer 12

¡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

Question 13

Co-aggregation

Question 14

Visual coaggregation scores for different pairs of strains.

Answer 14

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.

Question 15

Corncob and Bristle-brush

Question 16

How do biofilms form III

Answer 16

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

Question 17

Growth

Answer 17

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.

Question 18

Exopolysaccharide (EPS)

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

Answer 18

¡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
¡

Question 20

The EPS Matrix

Question 21

Mature Biofilm Structure

____ is key to survival of bacteria in biofilms

Answer 21

¡Diffusion is key to survival of bacteria in biofilms

Question 22

Properties of a Biofilm

Question 23

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

Answer 23

Species with different requirements can live together

Question 24

How do Mature Biofilm Communities Interact?

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

¡
¡
¡

Answer 24

¡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
¡
¡
¡

Question 26

Beneficial Nutritional Interactions in Plaque

Answer 26

Step and Actinomyces break down sugar to lactate

Veillonella in same vicinnity of strep because it eats lactate

Question 27

Protection

Biolfilm Protects against

____
____
____
____
____ ____

Answer 27

Bacteriophage

Phagocytes

Antibodies

Desication

Toxic Molecules

Question 28

Five Mechanisms of Increased Biofilm Tolerance to Antimicrobials

Answer 28

Antimicrobial Depletion

Slow penetration

Stress Response

Altered Microenvironment

Persisters

Question 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.

Answer 29

¡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.

Question 30

Gene Exchange

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

Answer 30

¡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?

Question 31

Quorum Sensing

• ¡The ability of bacteria to ____ ____ by producing ___ ____ molecules
• §Detect___ and ____ of bacteria
• Chemical signals called ________
• ¡Regulates interactions by ____ ____ ____of:
• • §A
    
    • §B
    • §E
    • §G
    • §A

Answer 31

¡The ability of bacteria to coordinate activities by producing small signaling molecules
§Detect # of bacteria
§Type of bacteria
§Auto-inducers
¡Regulates interactions by controlling gene expression of:
§Adherence
§Biofilm structure
§EPS production
§Gene exchange
§Antagonism
§

Question 32

Lifestyle Differences

• ¡Biofilm
  
  • ____ to a site
  • ____ metabolism
  • ____behavior
    
    • S_____ (___ ___)
    • E____ ____(___, ___)
    • I___ ____ (____ ____)
    • G___ ___ (____, ___ ____)
• ¡Planktonic
  
  • §May ___ or ____
  • §Grows and divides ___
  • §Each cell acts ____
  • §Laboratory cultures are grown _____

Answer 32

¡Biofilm
§Attached to a site
§Slowed metabolism
§Community behavior
▪Symbiosis (food webs)
▪Extended habitat (Oxygen, pH)
▪Increased virulence (gene transfer)
▪Group protection (chemicals, host defense)

¡Planktonic
§May swim or diffuse
§Grows and divides rapidly
§Each cell acts independently
§Laboratory cultures are grown planktonically

Question 33

Clinical Relevance

• ¡Biofilms form on :
  
  • ___ ___
  • ___ ____
    
    • ex)
• ¡Difficult to ___
  
  • ___ ___ mechanisms
  • ___ or ____ agents
  • §Require___ or ____ ____
• ¡Infections
  
  • §Acute-
  • §Chronic-
    *

Answer 33

¡Biofilms form on :
§Human tissues
§Medical/dental devices
▪Dental Unit Water Lines
¡Difficult to remove
§Immune system mechanisms
§Antibiotics or disinfecting agents
§Require mechanical or surgical removal
¡Infections
§Acute- planktonic bacteria
§Chronic- biofilm bacteria
§

Question 34

Clinical Biofilms

Answer 34

DENTAL PLAQUE!!! Many, many species