Bacterial infections of the GI Tract Flashcards

1
Q

H/o frequent vomiting early in the course of a GI tract disease indicates what usually?

A

Viral infection

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2
Q

High fever, lack of vomiting, abdominal pain with bowel movements, and the presence of gross blood and mucus in the stool suggest what type of cause?

A

Bacterial

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3
Q

What is the bacteria that is associated with improperly canned food?

A

Clostridium botulinum

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4
Q

Aerobic or anaerobic? Gram positive or negative? Cocci or bacillus? Spores? : Clostridium botulinum

A

Anaerobic
Gram positive
Rod
Spores

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5
Q

What is the MOA of botulinum toxin?

A

Inhibit the release of Ach from synaptic vesicles

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6
Q

Exotoxin or endotoxin: botulinum

A

Exotoxin

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7
Q

What are the ssx of botulinumism?

A

Descending weakness and paralysis
Dysphagia
Diplopia

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8
Q

Is the botulinum toxin heat stable or labile?

A

Will denature at 100 C for 15 minutes

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9
Q

What is the treatment for botulinum intoxication? What is the prognosis?

A

IV antitoxin (horse antibodies). This only binds to active toxin however, and thus it is a slow recovery

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10
Q

Aerobic or anaerobic? Gram positive or negative? Cocci or bacillus? Spores? : Clostridium difficile

A

Anaerobic
Gram Positive
Spore forming
Rod

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11
Q

What is the most common nosocomial cause of diarrhea?

A

Clostridium difficile

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12
Q

What abx is the most common cause of C.diff infections?

A

Cephaolsporins

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13
Q

True or false: C.diff does not invade intestinal tissue

A

True (well, rarely anyway)

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14
Q

What is the MOA of the exotoxin that C.diff produces?

A

Exotoxins A and B are enzymes that glycosylate a G protein involved in actin polymerization

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15
Q

What are the gross features of pseudomembranous colitis caused by C.diff?

A

White-yellow plaques

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16
Q

Is C.diff diarrhea bloody?

A

No

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17
Q

What is the treatment for C.diff?

A

Oral Metronidazole or vancomycin

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18
Q

Aerobic or anaerobic? Gram positive or negative? Cocci or bacillus? Spores? Lactose fermenter?: Shigella dysenteriae

A

Gram negative enteric rods

Non-lactose fermenting

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19
Q

What is McConkey agar used for? What are the results?

A

Tests for lactose fermentation

Color change = lactose fermenter

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20
Q

How do you differentiate Salmonella from Shigella?

A

Shigella:

  1. Produce no gas from fermentation
  2. Do NOT produce H2S gas
  3. They are non-motile
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21
Q

What type of diarrhea does shigella produce: bloody or not? Why?

A

Bloody– invasion of the intestinal epithelium causes blood and pus to form

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22
Q

What is the MOA of shigella? (does it produce a toxin? Does it invade cell walls)?

A

Produce a toxin and invade intestinal cell walls

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23
Q

What is the MOA of shigella toxin?

A

binds to ribosomes and halts transcription

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24
Q

What is the treatment for shigellosis?

A

IVF and lytes

If severe, fluoroquinolones (e.g. cipro)

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25
Q

Aerobic or anaerobic? Gram positive or negative? Cocci or bacillus? Motile? Lactose fermentation?: Salmonella?

A

Gram negative rods
NO lactose fermentation
Produce H2S
Motile

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26
Q

What are the two species of Salmonella that cause few GI symptoms?

A

S. Typhimurium

S. Enteritidis

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27
Q

What are the three types of Salmonella infections?

A

Enterocolitis
Enteric fever
Enteritidis

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28
Q

Which bacteria are not susceptible to HCl?

A

Shigella**

Campylobacter jejuni

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29
Q

Are S. Typhi or S. Enteritidis invasive?

A

If they cause disease, yes

30
Q

Where does S.Typhi bacteria typically multiply? What can this lead to?

A

Peyer’s patches

Bacteremia d/t dispersion

31
Q

What are the ssx of salmonella (besides Typhi)?

A

N/v
Abdominal pain
Diarrhea wwo blood

32
Q

What are the symptoms of S.Typhi infection?

A

ILI
Splenomegaly
Rose spots on the abdomen

33
Q

Rose spots on the abdomen in the setting of enterocolitis = ?

A

S. Typhi infection

34
Q

What is the treatment for Salmonellosis?

A

Supportive

Ceftriaxone if severe

35
Q

What organ typically holds Salmonella Typhi, and is the cause for the carrier state?

A

gallbladder

36
Q

How do you differentiate E.Coli from salmonella dn shigella?

A

E.coli will ferment lactose

37
Q

What happen with E.coli on MacConkey agar? What does this mean?

A

Turns the agar purple, meaning it ferments lactose

38
Q

What is the gram stain, morphology, lactose fementation results, for E.coli? Aerobic or anaerobic?

A

Gram negative rod
Facultative anaerobe
Ferments lactose

39
Q

What are the three antigens that E. Coli has?

A

O (in the cell wall)
H (flagella)
K (capsule)

40
Q

What is the disease that enterotoxigenic E.Coli causes (ETEC)? MOA?

A

Traveler’s (watery) diarrhea

cholera-like toxin and local adherence

41
Q

What is the disease that Enteroinvasive E.Coli causes (EIEC)? MOA?

A

Bloody diarrhea

Enters the intestinal epithelium, and destroys cells

42
Q

What is the disease that Enteropathogenic E.Coli causes (EPEC)? MOA?

A

Watery diarrhea in infants.

Adhere to intestinal wall and cause loss of microvilli

43
Q

What is the disease that Enterohemorrhagic E.Coli causes (EHEC)? MOA?

A

Bloody diarrhea

Produce shiga-like toxin

44
Q

What is the cause of hemolytic uremic syndrome? What is this?

A

EHEC

Hemolysis followed by renal failure

45
Q

What is the treatment for diarrhea caused by E.coli? What is the one strain that should not be given abx for? Why?

A

Supportive

EHEC d/t possibility to develop massive shia-like toxin release

46
Q

Rice water stool = ?

A

Cholera

47
Q

What is the gram stain and morphology of Vibrio Cholera?

A

Curved, gram negative rod

48
Q

What is the MOA of Cholera (generally)?

A

Adherence to intestinal GI mucosa via pili (but no visible damage)

Cholera toxin

49
Q

What is the MOA of cholera toxin?

A

AB protein that activates Gs, activating adenylate cyclase, and causing Cl channels to open and pump out Cl/water

50
Q

How does the body overcome a cholera infection?

A

Shedding of the intestinal cell wall

51
Q

What is the most common source of cholera infections?

A

Contaminated water or foods fertilized with human feces

52
Q

What is the treatment for cholera?

A

Supportive

53
Q

What is the gram stain and morphology of Campylobacter jejuni? Aerobic or anaerobic?

A

Curved, gram negative or

Microaerophilic

54
Q

What are the ssx of campylobacter jejuni infection?

A

fever, n/v/ diarrhea and abdominal cramps

55
Q

How do you diagnose Campylobacter Jejuni?

A

Stool culture in micoaerophilic conditions

56
Q

What is the treatment for campylobacter?

A

Supportive or erythromycin/cipro if severe

57
Q

What is the gram stain and morphology of helicobacter pylori? Aerobic?

A

Short, spiral, gram negative microaerophilic

58
Q

What is the enzymes that allows H.Pylori to survive in the low pH of the stomach?

A

Urease

59
Q

What is the route of transmission for H.pylori?

A

Fecal-oral route

60
Q

How do you distinguish between H.Pylori and Campylobacter?

A

H.pylori has urease

61
Q

What is the treatment for H.pylori?

A

PPI
Tetracycline
Clarithromycin

62
Q

Why is there no fever with botulinumism?

A

Toxin is the causative agent, not bacteria

63
Q

Will boiling of foods prevent botulinumism? Why or why not?

A

No– spores

64
Q

What are the histological characteristics of C.Botulinum?

A

Gram negative Rods with spores at the end

65
Q

What is the way to distinguish between diarrhea from other bacteria, and diarrhea caused by C.diff?

A

Toxins in the stool

66
Q

What is the severe adverse reaction with Fluoroquinolones?

A

Tendon rupture/tendinitis

67
Q

Match the MOA with the E.coli strain:

  1. Enterotoxin delivery
  2. Actin bundle pedestal formation
  3. Shiga toxin delivery
  4. Dissemination
A
  1. ETEC
  2. EPEC
  3. EIEC
  4. EHEC
68
Q

What is the serotype of EHEC that causes diarrhea?

A

0157:H7

69
Q

What is the major complication with EHEC?

A

Hemolytic uremic syndrome with abx use

70
Q

Will heating food prevent cholera?

A

Yes– cholera toxin will denature

71
Q

What is the odd thing about H.Pylori’s shape?

A

Multiple sheathed polar flagella

Corkscrew shape