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MIP 443 > Lecture 25 -- Biofilms > Flashcards

Lecture 25 -- Biofilms Flashcards

1
Q

this type of growth is not associated with planktonic cells/pure cultures, it is the most prevalent mode of growth and is associated with 80% of all infections, makes bacteria 1000x more resistant to antibiotics, and is often considered in chronic infections

A

biofilm

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2
Q

Antoine van Leeuwenhoek discovered what by noticing that bacteria protected the teeth of animals against vinegar

A

that biofilms on the surface had a tolerance to antimicrobial agents

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3
Q

communities of bacteria/microorganisms within a matrix

A

biofilm

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4
Q

What are the four reasons bacteria form biofilms

A
  • defense
  • adherence
  • close proximity to other cells
  • peer pressure
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5
Q

what part of a biofilm is important for adherence and structural support, protection from desiccation/biocides/antibiotics, and evasion of the immune system

A

matrix

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6
Q

List five things found in the matrix of biofilms

A
  1. Polysaccharides
  2. Proteins
  3. extracellular DNA
  4. Signaling molecules
  5. Water
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7
Q

List the three types of polysaccharides produced by bacteria and their locations

A
  • storage in the cell
  • capsular tightly adhered to cell surface
  • extracellular necessary for biofilms (ex: xanthan, cellulose, etc)
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8
Q

which exopolysaccharide is involved with cell to cell adhesion, pellicle formation, and is made up of 1–>4 linking of amines

A

Pel

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9
Q

which exopolysaccharide is important for surface attachment, biofilm structure and maintenance, and is made up of repeating pentasaccharides

A

Psl

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10
Q

where is pel located

A

at the periphery/stalk of biofilms

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11
Q

In biofilms, what molecule (or process) is incorporated into lipid A to reduce host inflammatory response

A

palmitate acyl chain (palmitoylation)

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12
Q

what enhances cell aggregation, attachment, and provides strength to biofilms

A

amyloids (fibrils)

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13
Q

what contributes a protein component important for initial attachment and matrix stabilization in biofilm formation

it is made up of a two-partner secretion system CdrAB

A

adhesins

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14
Q

which secretion system releases virulence factors and contains a passenger and translocator

A

Two-partner secretion (TPS) systems (CdrA & CdrB)

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15
Q

Which passenger virulence factor is a rod shaped protein with a beta helical structure?

A

CdrA

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16
Q

Which translocator protein is a beta barrel porin

A

CdrB

17
Q

Are biofilms homogenous?

A

No they can vary spatially and temporally and are physiologically distinct from planktonic cells

18
Q

What is upregulated in biofilm cells

A
  • LPS modifications
  • Efflux pumps
  • Oxidative stress response
  • Adherence
  • Genetic competence
19
Q

What is down-regulated in biofilm formation

A
  • protein synthesis
  • pili
  • flagella
20
Q

What happens to oxygen concentrations in biofilms as you get deeper

A

they decrease

21
Q

what does structuring the microbial community in a biofilm help with

A

allows access to more oxygen and other resources

22
Q

why are biofilms more tolerant to antimicrobials than planktonic cells?

A
  • matrix serves as barrier
  • there’s reduces metabolism and growth rates
  • they can express efflux pumps and stress response regulons “the biofilm phenotype”
23
Q

is the “biofilm phenotype” responsible for antibiotic tolerance or resistance and why

A

tolerance; if the film is disrupted, the bacteria die

24
Q

which two traditional antibiotic resistance mechanisms are active and upregulated in biofilms

A

efflux pumps and enzymes that degrade antibiotics

25
Q

what enzyme was found expressed in P. aeruginosa biofilms

A

beta-lactamase

26
Q

Which areas of a biofilm are targeted by aminoglycosides, fluoroquinolones, and tetracyclines?

A

high activity/surface bacteria

27
Q

Which areas of a biofilm are targeted by SDS, EDTA, Colistin, and Gallium

A

The center/dormant bacteria

28
Q

which cells survive an antimicrobial challenge in a biofilm and why are cells given enough time to initiate a stress response

A
  • the antimicrobial agent does not reach all the cells in a biofilm
  • viable cells that are metabolically inactive
29
Q

what comparison to bacterial biofilm communication can be made?

A

neurons in the brain

30
Q

what is the relationship between bacterial density and quorum sensing in bacteria

A

high bacterial density, high QS signal, increased gene activation or repression

31
Q

what effect do rhamnolipids have on biofilm architecture

A

they act as surfactants to disperse the biofilm and prevent spaces/channels from closing

32
Q

provide an example of how environmental conditions alter biofilm development

A

different carbon sources can determine whether a biofilm is flat or structured by altering surface motility

33
Q

List three developmental pathways biofilms can take

A
  • structured
  • structured with motile cap forming on immobile stalk
  • flat
34
Q

what do elevated levels of c-di-GMP cause with regard to biofilms

A

the production of exopolysaccharides and adhesins, DGC activity is increased

35
Q

what does depleted levels of c-di-GMP cause in biofilms

A

cells become planktonic and motile (in some cases, PDE activity is increased

36
Q

List four ways other organisms disrupt biofilms

A
  • lysins, depolymerases
  • proteases
  • lipases
  • nucleases
37
Q

what do glycoside hydrolases do

A

degrade and inhibit biofilms

38
Q

what is a genetic disease that disrupts CFTR (a protein that acts as a channel for the movement of chloride ions in and out of cells), this causes a buildup of mucus

A

cystic fibrosis

MIP 443 (14 decks)

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