Biofilms Flashcards

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1
Q

Definition of a biofilm

A

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

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2
Q

Biofilms are

A

Polymicrobial

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

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3
Q

In biofilms, there are

A

Cell - cell interactions

Adherence to a surface

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4
Q

Main infections caused by biofilms in tissues/fluids are

A

Bacteremia (blood stream infection)
UTI
Pneumonia

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5
Q

Sites of primary biofilm infection

A

Subvenous catheter
Mouth
Artificial hip implant

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6
Q

Five most common bacterial infections in an ICU

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

All form biofilms, can interact with each other

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7
Q

Biofilms have

A

Dispersal mechanisms, can move and help survival

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8
Q

Why are biofilms studied?

A
  1. Can cause disease
  2. Are reservoirs of contamination
  3. Are difficult to control
  4. Have economic cost
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9
Q

Examples of biofilm infection

A

Infection on heart valves
Dental decay
Implants

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10
Q

Examples of contamination reservoirs

A

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

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11
Q

TB tubercules are an example of

A

A bacterial biofilm

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12
Q

Biofilms are difficult to control because they require

A

Higher doses of antibiotics

Persister cells

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13
Q

Example of economic cost of biofilm

A

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

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14
Q

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

A

Burns patients

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15
Q

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

A

P. aerugensosa infection

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16
Q

Up to 65% of infections may be

A

Biofilm related

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17
Q

How many healthcare acquired infections are biofilm related?

A

60%

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18
Q

Nosocomial

A

Hospital acquired infection

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19
Q

When an organism forms a biofilm it

A

Changes its gene expression

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20
Q

When an organism adheres to a surface it often

A

Upregulates pathogenicity genes

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21
Q

Biofilm Plasticity

A

Gene flow through closely associated organisms, usually through plasmids

22
Q

When organisms are closely associated in a biofilm

A

Gene flow is more likely to occur

plasmids

23
Q

Advantages of living in a biofilm

A
  1. Increased resistance to antimicrobial agents
  2. Increased evasion of host defences
  3. Enhanced genetic interactions (R plasmids)
24
Q

Stages of biofilm formation

A
  1. Attachment
  2. Growth
  3. Detachment
25
Q

Attachment

A

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

26
Q

Growth

A

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

27
Q

Detachment

A

Allows growth

‘seeding’ of individual cells or large clumps

28
Q

Biofilms can move through

A

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

29
Q

The matrix is the

A
EPS
Dead cellular material
eDNA - environmental DNA
Sugars
Water
Architecture provides stability
Pores and channels
30
Q

In the matrix, localised gradients provide

A

Habitat diversity (aerobic vs anaerobic)

31
Q

Matrix sorption

A

Different ions absorbed into the EPS

32
Q

Enzymes in the matrix

A

Are retained and work better than in solution

33
Q

Co operation in the matrix

A

Quorum sensing

Synergystic micro-consortia

34
Q

Continuous regeneration

A

Is due to competition within the biofilm

35
Q

Tolerance and resistance

A

Biofilm like a ‘fortress’

R genes

36
Q

Oxygen gradients determine

A

Where certain bacteria grow in the biofilm

37
Q

Nutrient gradients determine

A

How fast a biofilm grows

38
Q

Diffusion reaction inhibition leads to

A

Tolerance of antimicrobials and toxic metals

39
Q

Examples of antibiotic resistance genes

A

B-lactamase

Efflux pumps

40
Q

Sublethal concentrations lead to

A

Selection for resistance

41
Q

The first biofilm to be studied was in the

A

Mouth

42
Q

The oral microbiome has

A

Over 700 species

43
Q

Mouth biofilm diseases

A

Decay
Mouth cancer
Gum disease

44
Q

How does plaque form?

A
  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
45
Q

Three main groups of plaque bacteria

A
  1. Aerobes
  2. Facultative anaerobes
  3. Obligate anaerobes
46
Q

Plaque aerobes

A
  1. High proportion in young plaque
  2. Do not usually cause harm
  3. e.g. Neisseria subflava
47
Q

Plaque facultative anaerobes

A
  1. Majority in plaque
  2. Able to grow in high + low O2
  3. Usually G +ve
  4. Streptococcus mutans
48
Q

Plaque obligate anaerobes

A
  1. In mature plaque
  2. Sometimes harmful
  3. Fusobacterium nucleatum
49
Q

Public prophylaxis

A

Fluoride use in water

50
Q

Fluoride mode of action

A

Reduces enzyme activity so less acid production from carbohydrates

51
Q

HAIs

A

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