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T1 - Phase 2 - Systems Modules (I) > Infectious Disease - Bacterial Basics > Flashcards

Infectious Disease - Bacterial Basics Flashcards

1
Q

How do bacteria typically replicate?

A

Binary fission

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2
Q

What is present in eukaryotic membranes but not prokaryotic membranes?

A

Sterols

(M. pneumoniae is an exception)

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3
Q

Describe the bacterial genome.

A

Single, circular, nucleoid

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4
Q

True/False.

Besides a nucleus, bacteria have virtually no membrane-bound organelles present.

A

False.

Bacteria have no membrane-bound organelles.

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5
Q

Describe the following according to shape type:

Cocci

Bacilli

Coccobaccilli

Spirochetes

Filamentous

Diplococci

A
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6
Q

______cocci typically appear in grape-like clusters.

______cocci typically appear in chains.

A

Staphylococci typically appear in grape-like clusters.

Streptococci typically appear in pairs or chains.

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7
Q

The purposes of the bacterial cell wall are mainly to prevent _________ damage and also to act as a _________ _________.

A

The purposes of the bacterial cell wall are mainly to prevent osmotic damage and also to act as a virulence factor.

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8
Q

Describe the general structural difference between Gram-positive and Gram-negative cells.

E.g. Which has a thicker cell wall? How many membranes or walls does each have? What structures are present?

A
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9
Q

Gram-positive bacteria

_______ (thin/thick) peptidoglycan layer

_______ (present/absent) techoic acids

_______ (present/absent) outer membrane

_______ (present/absent) LPS

_______ (present/absent) porins

A

Gram-positive bacteria

Thick peptidoglycan layer

Present techoic acids

Absent outer membrane

Absent LPS

Absent porins

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10
Q

Gram-negative bacteria

_______ (thin/thick) peptidoglycan layer

_______ (present/absent) techoic acids

_______ (present/absent) outer membrane

_______ (present/absent) LPS

_______ (present/absent) porins

A

Gram-negative bacteria

Thin peptidoglycan layer

Absent techoic acids

Present outer membrane

Present LPS

Present porins

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11
Q

Which is generally more susceptible to penicillins, Gram-negative or Gram-positive bacteria?

A

Gram-positive

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12
Q

Which is generally more susceptible to lysozymes, Gram-negative or Gram-positive bacteria?

A

Gram-positive

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13
Q

The four steps of Gram staining:

  1. _____________ is added.
  2. _____________ is added.
  3. Alcohol is added.
  4. Safranin is added.
A

The four steps of Gram staining:

  1. Crystal violet is added.
  2. Iodine is added.
  3. Alcohol is added.
  4. Safranin is added.
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14
Q

The four steps of Gram staining:

  1. Crystal violet is added.
  2. Iodine is added.
  3. _____________ is added.
  4. _____________ is added.
A

The four steps of Gram staining:

  1. Crystal violet is added.
  2. Iodine is added.
  3. Alcohol is added.
  4. Safranin is added.
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15
Q

In Gram staining, __________ is added to fix the crystal violet in place in Gram-positive cells.

A

In Gram staining, iodine is added to fix the crystal violet in place in Gram-positive cell walls.

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16
Q

In Gram staining, __________ is added to wash any non-fixed crystal violet from the cell.

A

In Gram staining, alcohol is added to wash any non-fixed crystal violet from the cell.

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17
Q
A

C. All the cells will be red

Iodine step ‘fixes’ purple crystal violet stain within Gram-positive cells.

Without iodine, the alcohol will clear the crystal violet out the Gram-positives and it will be replaced with the safranin red dye.

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18
Q

Gram-positive organisms stain _________ because of ________________ dye.

Gram-negative organisms stain _________ because of ________________ dye.

A

Gram-positive organisms stain purple because of crystal violet dye.

Gram-negative organisms stain pink because of safranin dye.

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19
Q

The organisms in this slide are Gram-_________.

What other designation would you give them?

A

The organisms in this slide are Gram-positive.

Streptococci.

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20
Q

The organisms in this slide are Gram-_________.

What other designation would you give them?

A

The organisms in this slide are Gram-positive.

Staphylococci.

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21
Q

The organisms in this slide are Gram-_________.

What other designation would you give them?

A

The organisms in this slide are Gram-negative.

Cocci.

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22
Q

The organisms in this slide are Gram-_________.

What other designation would you give them?

A

The organisms in this slide are Gram-negative.

Rods.

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23
Q
A

B.

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24
Q
A

B.

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25
Q

What is the major component of the outer membrane of Gram-negative bacteria?

A

Lipopolysaccharide

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26
Q

True/False.

O antigen is a major surface antigen present in every Gram-negative bacterial cell wall.

A

False.

O antigen is a major surface antigen present in many Gram-negative bacterial outer membranes.

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27
Q

Which bacteria are covered in endotoxin?

What is another name for this endotoxin?

A

Gram-negative;

LPS

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28
Q

The __ side chain of Gram-negative bacteria is immunogenic.

The ______ found in LPS is toxic.

A

The O side chain of Gram-negative bacteria is immunogenic.

The lipid A found in LPS is toxic.

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29
Q

Which toll-like receptor recognizes LPS?

A

TLR-4

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30
Q
A

C.

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31
Q

Bacterial capsules are especially important in preventing ___________ from occurring.

A

Bacterial capsules are especially important in preventing phagocytization from occurring.

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32
Q

Bacterial capsules are made of what?

A

Repeating polysaccharide units, protein, or both

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33
Q

True/False.

Bacterial capsules are important in biofilm formation.

A

True.

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34
Q

The two types of bacterial pilli are:

___________ — multiple per cell; enable adhesion

___________ — single per cell; enables conjugation

A

The two types of bacterial pilli are:

Common — multiple per cell; enable adhesion

Sex — single per cell; enables conjugation

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35
Q

Fimbriae and pilli both enable what bacterial process?

A

Adhesion

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36
Q

What protein makes up flagella?

A

Flagellin

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37
Q

Which toll-like receptor recognizes flagella?

A

TLR-5

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38
Q

For what two purposes are flagella useful in bacterial life?

A

Motility;

chemotaxis

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39
Q

True/False.

Many bacteria can quickly alter their flagellar arrangements to create different types of movement and/or different directions of movement and/or become stationary.

A

True.

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40
Q

What are the four phases of the bacterial lifecycle?

A

A. Lag

B. Log (exponential)

C. Stationary (plateau)

D. Death

41
Q

What term describes the length of time it takes for a bacterial generation to double?

(measured during ____ phase)

A

Doubling time

(measured during log phase)

42
Q

True/False.

Despite the many differences in the various families of bacteria, the doubling time remains relatively constant among bacterial species.

A

False.

The doubling time is highly variable among bacterial species.

(E.g.

  • E. coli* = ~20 min.;
  • M. tuberculosis* = >10 hours)
43
Q

True/False.

37°C is an optimal temperature for most bacterial growth.

A

True.

44
Q

Why is the normal bacterial colonization of our guts and skin actually protective against infection?

A

Invading bacteria have to compete for resources/space

45
Q

During which phase of bacterial growth are bacteria most sensitive to antibiotics?

A

Log phase

(high metabolic need and high replicative function)

46
Q

True/False.

In a latent infection, the M. tuberculosis doubling time is about 10 hours.

A

False.

In a latent infection, the M. tuberculosis doubling time is nearly 100 hours.

47
Q

Why are treatment courses for M. tuberculosis so long?

A

M. tuberculosis has an extremely slow doubling time

(bacteria are most sensitive during replication)

48
Q

_________ _________ need oxygen to survive.

_________ _________ are inhibited or killed by oxygen.

A

Obligate aerobes need oxygen to survive.

Obligate anaerobes are inhibited or killed by oxygen.

49
Q

Facultative aerobes/anaerobes use ___________ when oxygen is available and ___________ when it is not.

A

Facultative aerobes/anaerobes use respiration when oxygen is available and fermentation when it is not.

50
Q

When do microaerophiles grow best?

A

Low O2 saturation

(can also grow in absence of O2)

51
Q

Why are some bacterial species killed by oxygen?

A

Inability to deal with ROSs

52
Q

How is MacConkey agar selective and differential in promoting bacterial growth?

Selective: inhibits ____________ bacteria (crystal violet and bile salts present)

Differential: different appearance between those that can or cannot ____________ (pH indicator present)

A

Selective: inhibits Gram-positive bacteria (crystal violet and bile salts present)

Differential: different appearance between those that can or cannot ferment lactose (pH indicator)

53
Q

Lactose-fermenting organisms appear ______ on MacConkey agar.

Non-lactose-fermenting organisms appear ______ on MacConkey agar.

A

Lactose-fermenting organisms appear pink on MacConkey agar (acid produced).

Non-lactose-fermenting organisms appear gray on MacConkey agar (no acid produced).

(Image shows plating of a Gram-negative, lactose-fermenting bacteria.)

54
Q
A

D.

55
Q

What testing strip type is shown in the examples here?

For what are they useful?

A

Analytical profile index;

identifying infectious agents

56
Q

True/False.

Nutrient depletion triggers bacterial spore formation (by spore-forming bacteria).

A

True.

57
Q

Very, very few Gram-________ bacteria can form spores.

A

Very, very few Gram-negative bacteria can form spores.

58
Q

What are some potential triggers that might cause reactivation of bacterial spores to a vegetative state?

A

Presence of water + nutrients;

outer coat disruption (pH change, heat, mechanical stress, etc.)

59
Q
A

G. None of the above!

(Autoclave only)

60
Q

How can bacterial endospores be inactivated?

A

Autoclave only

61
Q

Can biofilms be removed from a surface via gentle rinsing?

A

No

62
Q

How can non-spore-forming bacteria survive large changes in temperature and other environmental conditions?

A

Biofilm formation

63
Q

Name a few common locations in the body and medical devices where biofilms can form.

A

Urinary catheters;

IUDs;

contact lenses;

plumbing systems;

tooth surface;

CF patient airways

(and many more)

64
Q

As part of their role in allowing bacterial colonies to survive harsh environments, biofilm formation also increases _____________-resistance.

A

As part of their role in allowing bacterial colonies to survive harsh environments, biofilm formation also increases antibiotic-resistance.

65
Q

Bacterial genomes are ______, ______coiled, and double-stranded, with few exceptions.

They are also ususally attached to the cell _________ and central structures.

A

Bacterial genomes are single, supercoiled, and double-stranded.

They are also ususally attached to the cell membrane and central structures.

66
Q

The lack of nuclear membrane means what for the central dogma within bacteria?

A

It is rapid

(transcription and translation occurring simultaneously)

67
Q

True/False.

Plasmids are self-replicating and often encode essential genes.

A

False.

Plasmids are self-replicating and rarely encode essential genes.

68
Q

What do plasmids often confer?

A

Selective advantage

(via antibiotic properties or virulence factors)

69
Q

Describe type III secretion systems.

A
70
Q

What portion of bacterial genomes often carry type III secretion systems and carry all the components of the bacterium’s necessary virulence factors?

A

Pathogenicity islands

71
Q

How do pathogenicity islands differ from normal chromosomal DNA (more G/C content or more A/T content)?

A

More G/C content

72
Q

True/False.

Many toxins and virulence factors are easily transferred via plasmids, prophages, transposons, and pathogenicity islands.

A

True.

Many toxins and virulence factors are easily transferred via plasmids, prophages, transposons, and pathogenicity islands.

73
Q

Name the type of bacterial genetic transfer represented by each of the following examples in this diagram:

Uropathogenic activity

Enterohemorrhagic activity

Enterotoxigenic activity

Enteropathogenic activity

A

Transposons

Transduction

Conjugation

Conjugation

74
Q

Transmission of genetic material between bacteria is usually exchange of __________ or chromosomal __________.

A

Transmission of genetic material between bacteria is usually exchange of plasmids or chromosomal fragments.

75
Q

What are the main mechanisms of bacterial genetic recombination?

A

Conjugation

Transposition

Transduction

Transformation

76
Q

What are the two main forms of transduction?

A

Generalized (accidental transfer of fragmented bacterial DNA into phages);

specialized (phage accidentally inserts a particular cleaved DNA into its own material)

77
Q

The two main forms of transduction are generalized and specialized. How do they work?

Generalized:

Specialized:

A

Generalized: a phage accidentally takes up fragmented bacterial DNA into its capsule instead of its own genetic material.

Specialized: a phage accidentally inserts a particular cleaved DNA fragment into its own genetic material.

78
Q

True/False.

Phage therapies may help in combatting resistant bacterial infections.

A

True.

79
Q

Bacterial genomics.

Replication –> ________ gene transfer

Recombination –> ________ gene transfer

A

Bacterial genomics.

Replication –> vertical gene transfer

Recombination –> horizontal gene transfer

80
Q

__________ — uptake of naked floating DNA floating (can be incorporated into chromosomes or plasmids);

__________ cells are cells able to take up naked DNA.

A

Transformation — uptake of naked floating DNA floating (can be incorporated into chromosomes or plasmids);

competent cells are cells able to take up naked DNA.

81
Q

Transposons are mobile genetic elements that often code for antibiotic resistance and are capable of self-replication

A

Transposons are mobile genetic elements that often code for antibiotic resistance but are incapable of self-replication

82
Q

Transposons can be either ________ (copy and paste) or non-________ (cut and paste).

A

Transposons can be either replicative (copy and paste) or non-replicative (cut and paste).

83
Q

Genes controlling what two enzymes mediate transposon activity?

A

Transposase and resolvase

84
Q

____________ can ‘jump’ between plasmids and chromosomes.

A

Transposons can ‘jump’ between plasmids and chromosomes.

85
Q

What can be expected to be transferred between F+ and F- cells via normal conjugation?

A

The F-plasmid (F-factor) only

86
Q

What can be expected to be transferred between F+ and F- cells via HFR (high-frequency recombination)?

A

The F-plasmid (F-factor)

+

some chromosomal material

87
Q

To test antibiotic resistance, place a ______ covered in ____________ on the agar to observe if any growth occurs on the ______.

A

To test antibiotic resistance, place a disc covered in the antibiotic on the agar to observe if any growth occurs on/around the disc.

88
Q

What agars are used to identify lactose fermentation in bacteria?

A

MacConkey or eosin methylene blue (EMB) agars

89
Q

In an A-B bacterial toxin, the ___ portion binds the cell, allowing for the ___ portion to enter and have an active effect.

A

In an A-B bacterial toxin, the B portion binds the cell, allowing for the A portion to enter and have an active effect.

91
Q

The O antigen is present on _________.

The K antigen is present on _________.

The H antigen is present on _________.

A

The O antigen is present on LPS.

The K antigen is present on capsules.

The H antigen is present on flagella.

92
Q

The ____ antigen is present on LPS.

The ____ antigen is present on capsules.

The ____ antigen is present on flagella.

A

The O antigen is present on LPS.

The K antigen is present on capsules.

The H antigen is present on flagella.

93
Q

All Gram-negative bacteria have endotoxin in the form of __________.

A

All Gram-negative bacteria have endotoxin in the form of Lipid A (extends from LPS).

94
Q

What is oxidase?

A

A respiratory enzyme involved in electron transport

95
Q

How do oxidase-positive bacteria present on oxidase testing?

How do oxidase-negative bacteria present on oxidase testing?

A
96
Q

What is chocolate agar?

A

Boiled blood agar

97
Q

What is Thayer-Martin agar?

A

Chocolate agar (boiled blood agar) + certain antibiotics

98
Q

What are the functions of teichoic acid and lipoteichoic acid in bacterial membranes?

A

Adhesion to host cells, antigenic

(also, weak endotoxin activity)

99
Q

In Gram-negative bacteria, which structure has endotoxin activity?

Which structure has anticomplement activity?

A

Lipid A;

O-antigen

T1 - Phase 2 - Systems Modules (I) (27 decks)

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