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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
What is the gram stain, aerobic/anaerobic and invasive properties of Salmonella Typhi?
Gram negative | Facultative anaerobe
26
Why can salmonella survive the stomach's low pH?
Acid tolerant
27
Which bacteria discussed is an intracellular pathogen?
Salmonella typhi
28
True or false: salmonella typhi can be found in pigs and other mammals
False-only humans
29
What is the route of transmission for salmonella typhi?
Fecal-oral
30
Is salmonella motile?
Yes--has flagella
31
What are the symptoms of typhoid fever?
Initially fever with HA Then prolonged "typhoid fever
32
Where does salmonella typhi usually colonize?
The gallbladder
33
What is the function of the M cells in the intestine?
Sample antigens in the intestine and present them to the Peyer's patches
34
What type of secretion system does salmonella typhi use?
Type III
35
What is the pathogenesis of salmonella typhi?
Ruffles membrane of the M cells, via secreation of SsP
36
What is the function of the SsPs that salmonella typhi produces?
Ruffles membrane of M cells, allowing the entry of the bacteria
37
How does our immune system become tolerant to all the food we eat?
M cells take up antigens and tolerizes them
38
Where does the salmonella Typhi go after it escapes into the cytoplasm of the intestinal cell?
Goes into macrophages, and migrates to lymph nodes
39
How does typhoid fever progress if it is an intestinal disease?
Migration of S. typhi from cells to lymph nodes. LPS
40
How do you diagnose S. Typhi?
Culture of stool and blood samples
41
What is the treatment for S. Typhi?
Abx based on susceptibility profile (fluoroquinonlones or trimethoprim-sulfamethoxazole)
42
What are the two vaccines for salmonella typhi?
Ty21A | ViCPS
43
What is the gram stain, aerobic/anaerobic, motile, and acidic, properties of nontyphoidal salmonella?
Gram negative Facultative anaerobe Motile Acid tolerant
44
What is the route of transmission for non-typhoidal salmonella?
Fecal-oral route
45
What are the symptoms of non-typhoidal salmonella? How long do they last?
n/v/d abdo pain for 3-4 days
46
How does non-typhoidal salmonella get into intestinal cells compared to typhoidal salmonella?
Same
47
What are the two immune responses to non-typhoidal salmonella infx?
1. Massive immune response in intestines | 2. Carriage in macrophages = sepsis (for immunocompromised)
48
How do you diagnose Non-typhodal salmonella?
Serology | Culture from blood and stool
49
What is the treatment for non-typhoidal salmonella?
Supportive, unless progresses to sepsis
50
Which bacterial infections should never be treated with abx? Why?
non-typhoidal salmonella, since it enhances the carrier state EHEC d/t increased expression of toxin
51
Is there a vaccine available for non-typhoidal salmonella?
No
52
What is the gram stain, aerobic/anaerobic and invasive properties of campylobacter jejuni?
Gram negative curved rods Microaerophilic Invasive
53
What are the two bacteria that have curved shapes?
Campylobacter jejuni | H. pylori
54
What is the disease caused by campylobacter jejuni
Ulceration, acute enteritis Sepsis
55
What is the sequelae of Campylobacter jejuni?
Guillain Barre syndrome (recall this is autoimmune disease against Schwann cells)
56
How do you diagnose campylobater jejuni?
Microaerophilic Culture
57
What is the treatment for campylobacter jejuni?
Supportive Abx iff invasive disease

Microbio (50 decks)

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