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NPLEX - Micro/Immuno > Principles of Bacteriology > Flashcards

Principles of Bacteriology Flashcards

1
Q

What is present in the wall of a gram + bacteria that is not present in a gram negative bacteria?

A

thick peptidoglycan layer

teichoic acid in wall

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2
Q

T/F: Spores are metabolically active.

A

false

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3
Q

How does bacterial infection cause fever?

A

endotoxin activates macrophages to release IL-1 and TNF, causing fever

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4
Q

Name 5 common zoonotic bacteria.

A

Borrelia burgdorferi, Brucella, Francisella tularensis, Yersinia pestis, Pasteirella multocida

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5
Q

Enterobaceriaceae: describe O, K, and H antigens

A

O - somatic, polysaccharide of endotoxin

K - capsular, related to virulence

H - flagellar, found in motile species

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6
Q

What kind of bacteria form spores and when?

A

certain gram + rods when nutrients are limited

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7
Q

Where is beta-lactamase in bacteria? What does it do?

A

periplasm of gram - bacteria

enzyme hydrolyzes beta-lactam antibiotics, conferring resistance

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8
Q

What molecule is specific to gram - bacterial cell membranes?

A

LPS

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9
Q

What are exotoxins and endotoxins, chemically speaking?

A

exotoxins tend to be polypeptides, while endotoxins are usually lipopolysaccharides

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10
Q

How could bacterial infection cause hypotension?

A

endotoxin induces macrophages to release nitric oxide -> vasodilation, hypotension

can also activate alternate complement pathway C3a, causing hypotension

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11
Q

Which organisms have exotoxin that acts by ADP ribosylation?

A

Corynebacterium diphtheriae, Escherichia coli, Vibrio cholerae, and Bordetalla pertussis

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12
Q

What helps organisms adhere to indwelling catheters?

A

glycocalyx (composed of polysaccharide)

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13
Q

Name the dominant normal flora on the teeth.

A

strep. mutans

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14
Q

Being in a newborn nursery is a risk factor for which two pathogens?

A

CMV and RSV

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15
Q

Name the dominant normal flora in the oropharynx.

A

strep. viridans

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16
Q

Name the dominant normal flora in the vagina.

A

Lactobacillus, E. coli, group B strep.

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17
Q

What disinfecting procedure kills spores?

A

autoclaving

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18
Q

Which pathogen is most associated with total parenteral nutrition?

A

Candida albicans

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19
Q

Where do bacteria keep their exotoxin or endotoxin genes?

A

exotoxin genes on plasmids or bacteriophages

endotoxin genes on bacterial chromosomes

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20
Q

T/F: we can vaccinate against exotoxins and endotoxins

A

false

we have toxoid vaccines against exotoxins for diseases like tetanus, botulism and diphtheria, but there are no vaccines against endotoxins

21
Q

T/F: Spores are highly resistant to destruction by heat and chemicals.

A

T

22
Q

Gram for gram, which is more fatal: exotoxin or endotoxin?

A

exotoxin

23
Q

Name the dominant normal flora in the colon.

A

Bacteriodes fragilis > E. coli

24
Q

How is catalase a virulence factor?

A

it degrades H2O2, an antimicrobial product of PMNs

25
Q

Name the dominant normal flora of the nose.

A

Staph. aureus

26
Q

Are vaccines available for encapsulated bacteria?

A

yes

27
Q

What are two of the most common causes of nosocomial infections?

A

E. coli (UTI) and Staph. aureus (wound infection)

28
Q

What are spores made of? What do they protect from?

A

keratin-like coat, dipicolinic acid

provide resistance to dehydration, heat and chemicals

29
Q

What is the major surface antigen of gram + cell walls and which two cytokines does it induce?

A

teichoic acid - unique to gram + bacteria

induces TNF and IL-1

30
Q

Spores have ___ acid in their core.

A

dipicolinic

31
Q

What are the two pathogens most commonly associated with urinary catheterization?

A

E. coli, Proteus mirabilis

32
Q

What is the most likely pathogen when a water source (water aerosols) is involved?

A

Legionella

33
Q

Name four organisms with IgA proteases.

A

Strep. pneumoniae, N. meningitidis, N. gonorhoeae, H. influenzae

34
Q

What pathogen is often found on respiratory therapy equipment?

A

Pseudomonas aeruginosa

35
Q

What is the main virulence factor of encapsulated bacteria and how does it confer virulence?

A

polysaccharide capsule is antiphagocytic

36
Q

Which has greater heat stability: endotoxin or exotoxin?

A

endotoxin

37
Q

Name the dominant normal flora in the skin.

A

Staph. epidermidis

38
Q

How might a bacterial infection cause disseminated intravascular coagulation?

A

endotoxin can activate Hageman factor which initiates coagulation cascade, causing DIC

39
Q

Compare and contrast the cell walls of Gram +/-

A

Both have peptidoglycan (Gram+ is thicker layer)
Gram - has LPS and LOS
Gram + has Lipoteichoic acid

40
Q

Compare and contrast antigenic variation and shift

A

Antigenic variation is the process by which bacteria alter the expression of certain genes in response to environmental stressors to promote survival and increase virulence. This process is faster than random mutation. An example of this is the changing of surface protein expression to avoid detection by host immune cells.

Antigenic shift is the exchange of genetic material between two subtypes of viruses to create progeny that is more virulent. This is commonly seen in influenza viruses.

41
Q

What is a plasmid

A

Plasmids can contain genes for antibiotic resistance or toxins. These plasmids can be freely replicated and transmitted between bacteria.

42
Q

If a bacteria is “competent” what does that mean?
3 examples

A

can facilitate the process of transformation (i.e., uptaking free genetic material from the environment and integrating it into the bacterial genome).

Neisseria species, Haemophilus influenzae type b, and Streptococcus pneumoniae.

43
Q

Generalized vs. specialized transduction

A

Generalized - phage DNA not integrated into bacterial chromosome
Specialized - specifically integrated into the chromosome

44
Q

Purpose of vanA gene?

A

Vancomycin resistance
Mostly seen in enterococcus species.

45
Q

Endotoxins are made of __ found on the __ of ___

A

LPS on the outer cell membranes of Gram - bacteria.

46
Q

MHCs bind ___ but not ___ , therefore they cannot present ___ to ___

A

bind peptide antigens, but not polysaccharides
therefore they cannot present endotoxins (made of polysaccharides) to TCRs (T cell receptors)

47
Q

AB toxins are part of ___
how do they work?

A

Exotoxins
1) Component A, the active component, enters the cell and exerts a toxic effect.
2) Component B, the binding and uptake component, binds to the target cell to facilitate entry of the toxin into the cell.

48
Q

Describe reassortment
what agent is best at this?

A

different strains of segmented viruses can combine to create a new viral subtype
Influenza - human + animal strain

49
Q
A

NPLEX - Micro/Immuno (18 decks)

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