L3 - Biofilms

Question 1

What is Planktonic

Answer 1

Free-living

Question 2

What is Biofilm

Answer 2

Sessile
Adherent

bacteria linked by EPS

Question 3

What is EPS?

Answer 3

Extracellular polymeric substance

Question 4

What is ECM?

Answer 4

Extracellular matrix

Question 5

What is the composition of a biofilm?

Answer 5

bacterial cells - 10-30%

EPS - 70-90%

Question 6

How are biofilms organised?

Answer 6

dynamic

specific areas

channel to bring water/nutrients deep

low flowing = mushroom/tower

high flow = streamer

Question 7

What are the stages of biofilm formation?

Answer 7

Initial attachment 
Irreversible attachment
Maturation I
Maturation II
Dispersion

Question 8

What triggers the biofilm developmental sequence?

Answer 8

dessication
antibiotics
HIGH CELL DENSITY
quorum sensing

PRODUCTION/DETECTION OF SIGNALLING MOLECULES

Question 9

What signalling molecule trigger biofilm development?

Answer 9

N-acyl homoserine lactones
Oligopeptides
Autoinducer-2

high conc. = changes in bacterial gene expression

Question 10

What are emergent properties?

Answer 10

behaviour the arise in a complex system - not predictable from study of individual components

Question 11

What are the emergent properties of biofilms?

Answer 11

Slower growth

Altered gene expression

antibiotics do not clear

immune sys do no clear

Increased development of ‘true’ antibiotic resistance - mutability increases in biofilm state

Question 12

What kind of organisms to biofilms contain?

Answer 12

non-growing

Question 13

What helps to reduce biofilm hypermutability?

Answer 13

antioxidants

Question 14

What factor is not involved in the REDUCED ability to detoxify ROS in the biofilm?

Answer 14

endogenous oxidative stress

Question 15

What are human infections involving biofilms?

Answer 15

catheters, contact lenses, valves…

Question 16

What are oral biofilms?

Answer 16

Gingivitis - plaque

Periodontitis - gum inflammation

Question 17

What is the issue with biofilms and wounds?

Answer 17

wounds may take years to heal

amputation

debridement works better than antibiotics

Question 18

How do device-associated biofilms occur?

Answer 18

colonise in medical devices

host inflammatory molecules

Surgical removal often required

Question 19

What’s involved in staphylococcal biofilms?

Answer 19

MSCRAMMs

adhesion to cell surfaces coated with host plasma proteins:

• fibronectin adhesins
• collagen-binding protein
• fibrinogen-binding proteins

Question 20

Biofilms and cystic fibrosis?

Answer 20

P.aeruginosa forms biofilm in lung - major cause of death

Pseudomonas cells covered with glycocalyx

Question 21

What is the Calgary Biofilm Device?

Answer 21

stain biofilm with crystal violet

more purple = more dense biofilm

Question 22

What is the use of repurposinng compounds with a history of human use?

Answer 22

look for anti-biofilm activity

redox-active agents

Question 23

How are anti-biofilm compounds (RA - redox-active agents) categorised?

Answer 23

2 groups on how they exert their effect

Type 1 cell killers - kill cells within biofilm

Type 2 matrix killers - restructuring, cells disperse and become planktonic so can be killed by antibiotics