Biofilms

Question 1

Definition of a biofilm

Answer 1

Matrix associated microbial populations adherent to each other and/or to surfaces or interfaces

Question 2

Biofilms are

Answer 2

Polymicrobial

Can be a mix of bacteria, or a mix of bacteria, fungi and viruses

Question 3

In biofilms, there are

Answer 3

Cell - cell interactions

Adherence to a surface

Question 4

Main infections caused by biofilms in tissues/fluids are

Answer 4

Bacteremia (blood stream infection)
UTI
Pneumonia

Question 5

Sites of primary biofilm infection

Answer 5

Subvenous catheter
Mouth
Artificial hip implant

Question 6

Five most common bacterial infections in an ICU

Answer 6

1. Pseudomonas aergenosa
2. Staphlococcus aureus
3. Escherichia coli
4. Coagulase-neagive staphylococci
5. Enterococci

All form biofilms, can interact with each other

Question 7

Biofilms have

Answer 7

Dispersal mechanisms, can move and help survival

Question 8

Why are biofilms studied?

Answer 8

1. Can cause disease
2. Are reservoirs of contamination
3. Are difficult to control
4. Have economic cost

Question 9

Examples of biofilm infection

Answer 9

Infection on heart valves
Dental decay
Implants

Question 10

Examples of contamination reservoirs

Answer 10

Food and food preparation, tissue surfaces, surfaces, intracellular biofilms (e.g. TB tubercules)

Question 11

TB tubercules are an example of

Answer 11

A bacterial biofilm

Question 12

Biofilms are difficult to control because they require

Answer 12

Higher doses of antibiotics

Persister cells

Question 13

Example of economic cost of biofilm

Answer 13

North sea steel pipes corroded by sulphate reducing bacterial biofilms
NHS costs

Question 14

As well as causing respiratory disease in CF patients, pseudomonas aerugenosa also colonizes

Answer 14

Burns patients

Question 15

Limb movement can encourage fluid flow in burns patients which helps protect from

Answer 15

P. aerugensosa infection

Question 16

Up to 65% of infections may be

Answer 16

Biofilm related

Question 17

How many healthcare acquired infections are biofilm related?

Answer 17

60%

Question 18

Nosocomial

Answer 18

Hospital acquired infection

Question 19

When an organism forms a biofilm it

Answer 19

Changes its gene expression

Question 20

When an organism adheres to a surface it often

Answer 20

Upregulates pathogenicity genes

Question 21

Biofilm Plasticity

Answer 21

Gene flow through closely associated organisms, usually through plasmids

Question 22

When organisms are closely associated in a biofilm

Answer 22

Gene flow is more likely to occur

plasmids

Question 23

Advantages of living in a biofilm

Answer 23

1. Increased resistance to antimicrobial agents
2. Increased evasion of host defences
3. Enhanced genetic interactions (R plasmids)

Question 24

Stages of biofilm formation

Answer 24

1. Attachment
2. Growth
3. Detachment

Question 25

Attachment

Answer 25

Free floating, planktonic bacteria encounter a submerged surface and become attached

Question 26

Growth

Answer 26

Extrapolymeric substances (EPS) formed by growing biofilm community to develop complex 3d structure

Question 27

Detachment

Answer 27

Allows growth | 'seeding' of individual cells or large clumps

Question 28

Biofilms can move through

Answer 28

Rippling, streaming, rolling, detachment, swarming and seeding dispersal

Question 29

The matrix is the

Answer 29

``` EPS Dead cellular material eDNA - environmental DNA Sugars Water Architecture provides stability Pores and channels ```

Question 30

In the matrix, localised gradients provide

Answer 30

Habitat diversity (aerobic vs anaerobic)

Question 31

Matrix sorption

Answer 31

Different ions absorbed into the EPS

Question 32

Enzymes in the matrix

Answer 32

Are retained and work better than in solution

Question 33

Co operation in the matrix

Answer 33

Quorum sensing | Synergystic micro-consortia

Question 34

Continuous regeneration

Answer 34

Is due to competition within the biofilm

Question 35

Tolerance and resistance

Answer 35

Biofilm like a 'fortress' | R genes

Question 36

Oxygen gradients determine

Answer 36

Where certain bacteria grow in the biofilm

Question 37

Nutrient gradients determine

Answer 37

How fast a biofilm grows

Question 38

Diffusion reaction inhibition leads to

Answer 38

Tolerance of antimicrobials and toxic metals

Question 39

Examples of antibiotic resistance genes

Answer 39

B-lactamase | Efflux pumps

Question 40

Sublethal concentrations lead to

Answer 40

Selection for resistance

Question 41

The first biofilm to be studied was in the

Answer 41

Mouth

Question 42

The oral microbiome has

Answer 42

Over 700 species

Question 43

Mouth biofilm diseases

Answer 43

Decay Mouth cancer Gum disease

Question 44

How does plaque form?

Answer 44

1. Primary colonizers attach to teeth and tissues 2. Secondary colonizers attach to primary colonizers 3. Plaque matures (growth and detachment) 4. Disease caused by toxins and acids being released

Question 45

Three main groups of plaque bacteria

Answer 45

1. Aerobes 2. Facultative anaerobes 3. Obligate anaerobes

Question 46

Plaque aerobes

Answer 46

1. High proportion in young plaque 2. Do not usually cause harm 3. e.g. Neisseria subflava

Question 47

Plaque facultative anaerobes

Answer 47

1. Majority in plaque 2. Able to grow in high + low O2 3. Usually G +ve 4. Streptococcus mutans

Question 48

Plaque obligate anaerobes

Answer 48

1. In mature plaque 2. Sometimes harmful 3. Fusobacterium nucleatum

Question 49

Public prophylaxis

Answer 49

Fluoride use in water

Question 50

Fluoride mode of action

Answer 50

Reduces enzyme activity so less acid production from carbohydrates

Question 51

HAIs

Answer 51

Catheters cause 95% UTIs Indwelling vascular devices cause 87% Bacteremias Ventilators cause 86% pneumonias