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Microbio > GI bacteria II > Flashcards

GI bacteria II Flashcards

1
Q

What is in MacConkey’s agar that ensure that only intestinal bacteria will grow?

A

Bile salts

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2
Q

What does the red indicate on MacConkey’s agar?

A

E.coli (can ferment lactose)

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3
Q

What does the white indicate on MacConkey’s agar? What type of bacteria will do this?

A

Negative for lactose fermentation

Salmonella, shigella

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4
Q

What does a negative result of an indole test indicate?

A

(no color change) Salmonella

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5
Q

What does a positive result of an indole test indicate?

A

(red color) E. Coli, Vibrip

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6
Q

What does a positive result on a hydrogen sulfite test look like? What is the agar used for this?

A

Black precipitate

S-S agar

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7
Q

What bacteria produces H2S? What does this distinguish between?

A

Salmonella

Distinguishes between salmonella and shigella

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8
Q

What are the four virotypes of E. coli?

A

ETEC
EPEC
EHEC
EIEC

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9
Q

What is the gram stain, aerobic/anaerobic and invasive properties of EPEC?

A

Gram negative
Facultative anaerobe
Moderately invasive

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10
Q

What does EPEC cause? In whom?

A

Watery diarrhea in children

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11
Q

How does EPEC cause disease? (what is the protein on the bacteria, and what is the protein on the intestinal epithelium? What type of secretion system does it use? Are toxins involved?)

A

BfpA on epithelial cells binds to intimin on bacteria.

Type III secretion of Tir

No toxins

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12
Q

What is a type III secretion system?

A

When a bacteria injects stuff directly into host cells

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13
Q

What is the actual cause of damage that EPEC does, if it does not produce toxins?

A

Destroys epithelial cell microvilli, disrupting water reuptake

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14
Q

Which bacteria utilizes an “attaching and effacing” mechanism?

A

EPEC

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15
Q

How can you diagnose EPEC? (2)

A

Culture + lactose fermentation and indole testing

PCR

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16
Q

What is the treatment for EPEC?

A

Supportive

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17
Q

What is the gram stain, aerobic/anaerobic and invasive properties of ETEC?

A

Gram negative
Facultative anaerobe
Non-invasive

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18
Q

What disease does ETEC cause?

A

Travelers’ diarrhea

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19
Q

How does ETEC attach to epithelial cells (protein?)

A

Via Fimbriae

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20
Q

What are the toxins that ETEC produces? Which is heat stable and which is heat liable?

A

LT toxin (heat liable) and ST toxin (heat stable)

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21
Q

What type of toxin is the LT-heat liable toxins that ETEC produces? What is its effect?

A

AB toxin

cAMP upregulator

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22
Q

What type of toxin is the ST-heat stable toxins that ETEC produces? What is its effect?

A

Non-AB toxin

Increases cGMP

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23
Q

What is the treatment for ETEC poisoning?

A

Supportive

24
Q

How do you diagnose ETEC? (2)

A

History

DNA probes

25
Q

What is the gram stain, aerobic/anaerobic and invasive properties of Salmonella Typhi?

A

Gram negative

Facultative anaerobe

26
Q

Why can salmonella survive the stomach’s low pH?

A

Acid tolerant

27
Q

Which bacteria discussed is an intracellular pathogen?

A

Salmonella typhi

28
Q

True or false: salmonella typhi can be found in pigs and other mammals

A

False-only humans

29
Q

What is the route of transmission for salmonella typhi?

A

Fecal-oral

30
Q

Is salmonella motile?

A

Yes–has flagella

31
Q

What are the symptoms of typhoid fever?

A

Initially fever with HA

Then prolonged “typhoid fever

32
Q

Where does salmonella typhi usually colonize?

A

The gallbladder

33
Q

What is the function of the M cells in the intestine?

A

Sample antigens in the intestine and present them to the Peyer’s patches

34
Q

What type of secretion system does salmonella typhi use?

35
Q

What is the pathogenesis of salmonella typhi?

A

Ruffles membrane of the M cells, via secreation of SsP

36
Q

What is the function of the SsPs that salmonella typhi produces?

A

Ruffles membrane of M cells, allowing the entry of the bacteria

37
Q

How does our immune system become tolerant to all the food we eat?

A

M cells take up antigens and tolerizes them

38
Q

Where does the salmonella Typhi go after it escapes into the cytoplasm of the intestinal cell?

A

Goes into macrophages, and migrates to lymph nodes

39
Q

How does typhoid fever progress if it is an intestinal disease?

A

Migration of S. typhi from cells to lymph nodes. LPS

40
Q

How do you diagnose S. Typhi?

A

Culture of stool and blood samples

41
Q

What is the treatment for S. Typhi?

A

Abx based on susceptibility profile (fluoroquinonlones or trimethoprim-sulfamethoxazole)

42
Q

What are the two vaccines for salmonella typhi?

A

Ty21A

ViCPS

43
Q

What is the gram stain, aerobic/anaerobic, motile, and acidic, properties of nontyphoidal salmonella?

A

Gram negative
Facultative anaerobe
Motile
Acid tolerant

44
Q

What is the route of transmission for non-typhoidal salmonella?

A

Fecal-oral route

45
Q

What are the symptoms of non-typhoidal salmonella? How long do they last?

A

n/v/d abdo pain for 3-4 days

46
Q

How does non-typhoidal salmonella get into intestinal cells compared to typhoidal salmonella?

47
Q

What are the two immune responses to non-typhoidal salmonella infx?

A
  1. Massive immune response in intestines

2. Carriage in macrophages = sepsis (for immunocompromised)

48
Q

How do you diagnose Non-typhodal salmonella?

A

Serology

Culture from blood and stool

49
Q

What is the treatment for non-typhoidal salmonella?

A

Supportive, unless progresses to sepsis

50
Q

Which bacterial infections should never be treated with abx? Why?

A

non-typhoidal salmonella, since it enhances the carrier state

EHEC d/t increased expression of toxin

51
Q

Is there a vaccine available for non-typhoidal salmonella?

52
Q

What is the gram stain, aerobic/anaerobic and invasive properties of campylobacter jejuni?

A

Gram negative curved rods

Microaerophilic

Invasive

53
Q

What are the two bacteria that have curved shapes?

A

Campylobacter jejuni

H. pylori

54
Q

What is the disease caused by campylobacter jejuni

A

Ulceration, acute enteritis

Sepsis

55
Q

What is the sequelae of Campylobacter jejuni?

A

Guillain Barre syndrome (recall this is autoimmune disease against Schwann cells)

56
Q

How do you diagnose campylobater jejuni?

A

Microaerophilic Culture

57
Q

What is the treatment for campylobacter jejuni?

A

Supportive

Abx iff invasive disease

Microbio (50 decks)

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