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Medical Microbiology > Lecture 13: Biofilms > Flashcards

Lecture 13: Biofilms Flashcards

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Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

True or False: Bacterial growth in the real world remain in log phase for a longer time, but remain slower

A

True

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2
Q

____: collection/mixture of microorganisms (bacteria, fungi, etc) living in a polysaccharide matrix, which is secreted by one or more membrane, attached to either a solid biologic or non-biologic surface

A

Biofilms

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3
Q

True or False: The biofilms can live on surface of anything, but prefer moist environment (e.g polysaccharides, glycoproteins on surface)

A

True

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4
Q

Biofilms typically live in communities, which is a way to create a stable ___ with adequate access to food, water, atmosphere, etc.

A

habitat

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5
Q

Biofilms produce _____ (EPS), which facilitate attachment and matrix formation and become IRREVERSIBLY attached

A

extracellular polymeric substances (EPS)

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6
Q

Why are biofilms so highly hydrated?

A

Open channel structures

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7
Q

True or False: Biofilms are complex 3D structures that vary in thickness and grow faster than planktonic organisms

A

False - while biofilms are complex 3D structures that vary in thickness, they grow SLOWER than planktonic organisms (they have a longer generation time)

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8
Q

What is the function of the EPS in biofilms?

A. Adhesion
B. Attachment
C. Reproduction

A

B. Attachment

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9
Q

What type of associations among several microbial groups (fungi, bacteria, algae, protozoa) as well as plants and animals create mutually favorable environments?

A

Cooperative Associations

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10
Q

How do biofilm cells coordinate their behavior?
A. Intracellular, cell:cell communication
B. Extracellular, cell:cell communication
C. Extracellular, receptor tyrosine kinase

A

A. Intracellular, cell:cell communication

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11
Q

True or False: Quorum sensing requires biochemical signaling molecules and is utilized by biofilms to coordinate behavior

A

True

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12
Q

What are the three benefits to biofilm of living in complex, organized communities?

A
  1. Able to break down complex nutrients
  2. Can alter phenotype
  3. Enhanced survival
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13
Q

What is the first stage of the biofilm lifecycle?
A. Attachment stage
(surface conditioning and attachment)
B. Growth Stage
B.
C.

A
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14
Q

During the attachment stage of the biofilm life cycle, which materials will develop biofilms more rapidly?
A. Rougher and more hydrophilic
B. Rough and more hydrophobic
C. Smoother and more hydrophilic
D. Smoother and more hydrophobic

A

B. Rough and more hydrophobic

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15
Q

A sediment of ___ molecules helps form a conditioning layer for biofilm during the Attachment Stage
A. organic molecules
B. inorganic molecules

A

A. organic molecules

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16
Q

Who are the first colonists in the attachment stage of the biofilm life cycle?
A. Fungi
B. Protists
C. Bacteria
D. Me

A

C. Bacteria

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17
Q

Initial attachment of biofilms is based on….
A. Electrostatic attraction only
B. Physical forces only
C. Both physical forces and electrostatic attraction
C. Neither physical forces nor electrostatic attraction

A

C. Both physical forces and electrostatic attraction

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18
Q

True or False: Growth media, substratum, and cell surfaces regulates the attachment stage of the biofilm life cycle

A

True

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19
Q

During the attachment stage of the biofilm life cycle, which structure enables the cell to remain attached until more permanent attachment mechanisms are in place?
A. Appendages
B. Flagella
C. Plasmid

A

A. Appendages

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20
Q

Why do early cells in the attachment stage multiply then become permanently adhered (irreversible adsorbed)?
A. Production of gap junction
B. Production of organic molecules
C. Production of LPS
D. Production of EPS

A

D. Production of EPS
- Increase the binding of cells to surface, thickens biofilm

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21
Q

Which stage of the biofilm life cycle is associated with the development of a complex, 3D structure?

A

Growth Stage

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22
Q

True or False: Biofilms evolve during the Growth Stage

A

True

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23
Q

The earliest colonist contribute ____ and create microhabitats that serve as a matrix for other microbes to attach

A

nutrients

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24
Q

At what stage of the biofilm life cycle do complete communities form?
A. Stage 1 (Attachment Stage)
B. Stage 2 (Growth Stage)
C. Stage 3 (Maturation and Dispersal)

A

B. Stage 2 (Growth Stage)

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25
Q

At what stage in the biofilm life cycle does the biofilm begin releasing cells and other debris into its environment, which then attaches to a new surfaces and starts a new cycle?
A. Stage 1 (Attachment Stage)
B. Stage 2 (Growth Stage)
C. Stage 3 (Maturation and Dispersal)

A

C. Stage 3 (Maturation and Dispersal)

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26
Q

True or False: The Growth Stage is associated with causing chronic and persistent infection

A

False - Dispersal Stage (3rd stage)

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27
Q

What are the three stages of the biofilm life cycle?

A
  1. Attachment
  2. Growth
  3. Dispersal
28
Q

True or False: Biofilms are more susceptible to phagocytosis, drugs, or neutralizing antibodies

A

False - LESS susceptible

The susceptibility could be intrinsic (natural outcome of growth) or acquired (due to transfer of ECE to organisms in biofilm and alter gene transcription)

29
Q

True or False: The susceptibility of biofilms to anti-microbial agents can be determined by MIC or MBC

A

False - cannot be because these test rely upon response of planktonic microorganisms - not biofilm microorganisms!

30
Q

What type of infections can arise in patients with biofilms (persistent source of infection)?

A

Blood stream or urinary tract

31
Q

What is the most effective way of treating infections due to biofilms on patients with medical devices?

A

Remove biofilm-contaminated devie

32
Q

True or False: Bacteria colonizing chronic wounds exist as biofilms communities. Biofilms prevent wound healing.

A

True

33
Q

What are four alternative biofilm control strategies?

A
  1. Quorum sensing inhibitors
  2. Use natural/synthetic iron scavenging
  3. Inhibit cell adhesions by treating surface w/synthetic peptides
  4. Degrade compounds for biofilm formation
  5. Better delivery of antimicrobial agents
    (weak electric fields enhance efficacy of abx - bioelectric effect)
34
Q

_____: Enzyme that targets the gelatinous matrix of biofilm

A

Dispersin B
- used to removed S. epidermidis biofilms

35
Q

True or False: Removal and anti-microbial prophylaxis (coating, immersion) are the best to control biofilm

A

True

36
Q

Biofilms have intrinsic antimicrobial resistance resistance. What are 3 examples?

A

1 - EPS Matrix (hard to diffuse through)
2 - Reduced growth rates - which means one minimizes rate that antimicrobial agents are taken up
3 - Environment surrounding biofilm may protect organism (e.g disinfectants)

37
Q

True or False: Transfer of plasmid is enhanced in biofilms compared to a regular environment

A

True

38
Q

True or False: Acquired resistance to antimicrobial comes from both genotypic and phenotypic

A

True

39
Q

Alternation of gene transcription and increased chances for transformation are examples of….
A. Acquired Resistance to Anti-Microbials
B. Intrinsic Resistance to Anti-Microbials

A

A. Acquired Resistance to Anti-Microbials

40
Q

What are ecological strategies for making biofilms? defense and survival?

A
  1. Prevents deattachment
  2. Cell communication and cooperation
  3. Nutrient adsorption
  4. Avoid predation
  5. Resist physical forces
41
Q

True or False: Adherent bacterial cells from biofilms

A

True

42
Q

Phagocytic enzymes damage tissues around biofilm, leading to release of planktonic bacteria from biofilm. Release may cause dissemination and acute ___ in neighboring cells

A

infection

43
Q

______: A relatively new field of study, which focuses on the coordination of bacteria behavior in their environment

A

Cellular signaling

44
Q

True or False: Coordinated bacterial movement is result of communication between bacteria

A

True

45
Q

True or False: Quorum sensing is one type of bacterial cell-cell communication; it could be intra or interspecies

A

True

46
Q

Bacteria sense their own cell density signaling molecules, also called ____, that they produce and release in the environment

A

autoinducers

47
Q

Where do autoinducers accumulate during cell growth?

A

Outside of cell

48
Q

When does the signal transduction cascade activate gene expression?

A

Once concentration of autoinducers/signal molecules reach certain threshold

49
Q

True or False: In biofilms, target genes can coordinate cell behavior in a density-dependent manner

A

True

50
Q

Which stage of the biofilm lifecycle does quorum sensing play largest role in?

A

Growth Stage

51
Q

In which case is quorum sensing most likely to occur?
A. Planktonic organism
B. Biofilm

A

B. Biofilm
- While planktonic cells secrete chemical signals, low concentration of signal molecules does not change gene expression

52
Q

What are four types of autoinducers?

A
  1. N-acyl-L-homoserinelactones (AHL)
  2. Peptides
  3. Butyrolactones
  4. Furanosylborate diester
53
Q

True or False: AHL (N-acyl-L-homoserinelactones) is mostly made by gram negative bacteria while Peptides are mostly made by gram positive bacteria

A

True

54
Q

AI-2, V. Harveyi is associated with which autoinducer?
A. N-acyl-L-homoserinelactones (AHL)
B. Peptides
C. Butyrolactones
D. Furanosylborate diester

A

D. Furanosylborate diester

55
Q

AHL’s, LuxI, and LuxR were first discovered in V. fischeri. which bacteria relies on similar systems?
A. Gram (-) Bacteria
B. Gram (+) Bacteria

A

A. Gram (-) Bacteria

56
Q

AHL’s are produced by ___-like proteins and detected by ____-type proteins
A. LuxR-like, Lux-I-like
B. Lux-I-like, LuxR-like
C. Lux P, Lux-I like

A

B. Lux-I-like, LuxR-like

57
Q

True or False: AHL’s freely diffuse across cell membrane and increase concentration in environment in proportion to cell growth

A

True

58
Q

____, when bound to cognate auto inducers, bind specific promoter DNA elements and active transcription of target genes
A. Lux-R Type Proteins
B. LuxI
D. AHL’s

A

A. Lux-R Type Proteins

59
Q

True or False: Gram Negative bacteria use peptides as autoinducers

A

False - gram (+) do

60
Q

In gram (+) bacteria, detection for quorum sensing occurs via a ________ circuit, which leads to phosphorylation of response regulator protein of a sensor kinase

A

two component signal transduction circuit

61
Q

How do gram (-) bacteria do quorum sensing?

A
62
Q

What two autoinducers are produced by the gram negative bacterium V. harveyi?

A

HAI-1 and AI-2

63
Q

HAI-1 is a typical gram negative-like AHL, although its synthesis is not dependent on a Lux1-like enzyme. It is actually produced by ____
A. LuxI
B. LuxP
C. LuxS
D. LuxLM

A

LuxLM

64
Q

AI-2, made by gram negative bacterium V. harveyi, is a furanosyl borate ____made by Lux__
A. diester; LuxPR
B. diester; LuxI
C. diester; LuxS

A

C. diester; LuxS

65
Q

HAI-1 and AI-2 signal transduction occurs via: ____

A

gram positive like phosphorylation cascade (TCST)

66
Q

___: The soluble periplasmic AI-2 binding protein that is critical for AI-2 signal transduction
A. LuxS
B. LuxT
C. LuxP

A

C. LuxP

Medical Microbiology (31 decks)

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