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ICOM- GI system > GI- Micro- Diarrhea > Flashcards

GI- Micro- Diarrhea Flashcards

1
Q

Gatrotenteritis usually involves the stomach and the intestine and acute infectious diarrhea involves the and large intestine.

A

small intestine

small intestine

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2
Q

What are the 3 types of exotoxins?

A

Type I- Membrane-Acting Toxins

Type II- Membrane- Disrupting Toxins

Type III- Intracellular-Acting Toxins

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3
Q

Which exotoxin type binds to the host cell surface receptors and stimulate transmembrane signals (act in extracellular space)?

Ex- Superantigens (MHC and T cells) and some enterotoxins

A

Type I -Membrane -Acting toxins

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4
Q

Which exotoxin type acts on the host cell membranes and exert effects by damaging them?

-pore-forming toxins (C. Perfingens) and phospholipases and some enterotoxins

A

Type II- Membrane-Disrupting Toxins

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5
Q

Which extotoxin type has a binding region that binds a specific receptor (endocytosed) and activity regions that act on some intracellular target molecule?

-: A-B toxins and some enterotoxins

A

Type-III - Intracellular toxins

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6
Q

What type of toxins do enterotoxins express?

A

enterotoxins fall under all 3 enterotoxin types

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7
Q

What are protein toxins that cause diarrhea or vomiting where the host target is usually the intestines and sometimes Vagus N?

A

Enterotoxins

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8
Q

What exotoxin type is produced by Staphyloccocal enterotoxins A-E and and Heat-stable enterotoxin A (STa) and B(STb) of Escheriachia coli?

A

Type I- Membrane-acting toxins

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9
Q

What type of toxin is expressed by Clostridium perfringens?

A

Type II- membrane disrupting (pore forming)

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10
Q

What type of exotoxin type?

C. jejuni - Cytolethal distending toxin (Cj-CDT)

C. difficile Toxin A and B

Shiga toxins 1 & 2

A

Type III- Intracellular acting toxins (AB toxins)

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11
Q

What do the A and B subunits (Type III toxin) do?

A

A= activity (interacts with and usually interferes with intracellular processes).

A separates from B and gains access to cell cytoplasm

B=Binding (responsible for cellular specificity - mediates attachment and entry)

B mediates endocytosis into the cell

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12
Q

Which vibrio species is described:

Source of infection: fresh water

Route of infection: oral

clinical manifestation: cholera and gastroenteritis; rarely wound infections

A

Vibrio Cholerae O1 or O139

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13
Q

Which vibrio species is described:

Source of infection: seafood, sea water

Route of infection: oral and wound

clinical manifestation: gastroenteritis, wound and ear infxn

A

vibrio cholera (other strains- not O1 or O139)

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14
Q

Which vibrio species is described:

Source of infection: seafood

Route of infection: oral and wound exposure

clinical manifestation: Gastroenteritis & wound infections

A

Vibrio parahaemolyticus

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15
Q

Which vibrio species is described:

Source of infection: sea food, sea water

Route of infection: oral and wound exposure

clinical manifestation: gastroenteritis, wound infections, sepsis

A

Vibrio vulnificus

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16
Q

Describe vibrio species

A

gram negative

flagellated

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17
Q

Which vibrio is being described (cholerae, parahaemolyticus, or vulnificus):

Cholera- it begins with an abrupt onset of watery diarrhea and vomiting and can progress to severe dehydration, metabolic acidosis and hypokalemia, and hypovolemic shock

Gastroenteritis: milder form of diarrheal disease can occur in toxin-negative strains of V. cholerae O1 and non-O1 serotypes

A

Vibrio cholerae

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18
Q

Which vibrio is being described (cholerae, parahaemolyticus, or vulnificus):

gastroenteritis: it is generally self-limited, with an explosive onset of watery diarrhea and nausea, vomiting, abdominal cramps, headache, and low grade fever

wound infection: associated with exposure to contaminated water

A

vibrio parahaemolyticus

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19
Q

Which vibrio is being described (cholerae, parahaemolyticus, or vulnificus):

wound infection: severe, potentially fatal infections characterized by erythema, pain, bullae formation, tissue necrosis, septicemia

A

vibrio vulnificus

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20
Q

Which serogroups of v. cholerae can cause epidemic cholerae?

A

O1 and O139

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21
Q

Which V. cholerae virulence factors are described?

1.-hypersecretion of electrolytes and water

2-surface binding site receptor, mediates bacterial adherence to intestinal mucosal cells

3-adhesin factor

4-increases intestinal fluid secretion

5-increases intestinal permeability

A

1 cholera toxin

2 toxin coregulated pilus

3 chemotaxis

4 accessory cholera enterotoxin

5 zonula occludens toxin

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22
Q

Which Vibrio species:

  • Kanagawa hemolysin (thermostable direct hemolysin [Vp-TDH]) - induces chloride secretion for watery diarrhea
  • MOA includes increasing intracellular Ca2+

green colony on TCBS agar

A

V. parahaemolyticus

green colonies on the top

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23
Q

What is Kanagawa hemolysis and with which vibrio species is it associated?

A

B-hemolyticus on human blood agar, not sheep

[green colonies on Thiosulfate Citrate Bilesalts Sucrose (TCBS) agar because does not ferment sucrose]

V. parahaemolyticus

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24
Q

The V. cholerae toxins toxin coregulated pilus (TCP) and chemotaxis protein are what type of toxins?

A

attachment toxins to mucosa

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25
Q

Which 3 toxins contribute to waterry diarrhea in v. cholerae?

A

Cholera toxin (CTX)

Accessory cholera enterotoxin

zonula occludens toxin

note: rice water diarrhea (water, electrolytes, mucus)

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26
Q

V. cholerae produces no/some damage to the enterocytes, some/massive loss of fluid and electrolytes, no/some blood and WBCs in stool, and requires a high/low infectious dose?

A

no damage to enterocytes

massive loss

no blood and WBCs

high infectious dose

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27
Q

Describe the pathogenesis of V. cholerae?

A
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28
Q

Which V. cholerae toxin has 2 subunits that causes binding and endocytosis of the units in which the a is separated, stimulates GPCR, then AC pathway to increased cAMP and PKA to phosphorylated CFTR for electrolyte loss?

A

cholera toxin (CTP)

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29
Q

Which campylobacter species comes from poultry, cattle, sheep and can present with gastroenteritis, Guillain-Barre, and reactive arthritis?

A

Campylobacter jejuni

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30
Q

Which Campylobacter species is associated with pigs, poultry, sheep, and birds and is related to gastroenteritis and extraintestinal infections?

A

Campylobacter coli

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31
Q

Which diarrheal bacterial species is transmitted through consumption of undercooked or contaminated food or via contact with animals (a true zoonotic organism)?

A

campylobacter species

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32
Q

What is a major pathogen for inflammatory diarrhea and uses cytolethal distending toxin (CDT), a genotoxin, that causes histological damage to mucosal surfaces (absorptive microvilli) of the jejunum, ileum, and colon from e induction of G2/M cell cycle arrest leading to apoptosis ?

A

Campylobacter jejuni

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33
Q

What entero pathogen is associated with antibiotic use within the last 30 days that can result in pseudomembranous colitis (severe bloody diarrhea)?

A

C. difficile

34
Q

Treatment with antibiotics causes massive death of the commensal bacteria that normally colonize the colon. This allows pathogenic bacteria to proliferate and to occupy an ecological niche that is normally occupied by harmless commensal bacteria. is an example of producing toxins that can cause severe bloody diarrhea in patients treated with antibiotics.

A

Clostridium difficle

35
Q

What enteropathogenic species is being described:

  • Two AB toxins
  • Toxin A (TcdA) and B (TcdB) [both A or activity subunits] can activate glycosyltransferases that inactivate targets by adding a sugar moeity and can lead to apoptosis
  • TcdA can activate inflammatory cells (cytokines, chemokines, ROS)
  • TcdB activity leads to disruption of tight junctions and apoptosis.
A

Clostriodioides difficile

36
Q

What is the virus that is a double capsid dsRNA (segmented) virus (which is unique) that can cause viral gastroenteritis?

  • is associated more with diarrhea than vomit
  • common in children 6 months - 2 yrs (<5 yrs worldwide)
  • is also associated with respiratory symptoms
A

Reoviridae- Rotavirus

37
Q
  • rotovirus is/is not associated with food
  • rotovirus has/ does not have a vaccine
  • rotovirus is/is not common of persistent/chronic in HIV+
A
  • is not associated with food
  • does have a vaccine
  • is not common in HIV+
38
Q

What viral gastroenteritis is associated with children with T cell deficiencies, nursing homes, and college dorms?

A

Rotovirus

39
Q

What is the clinical presentation of adults infected with rotovirus?

A

mild, asymptomatic

40
Q

With rotovirus, a double capsid dsRNA virus, where does transcripton take place?

A

the capsid is uncoated and mRNA transcription occurs in the viral particle in the cytoplasm of host cell and then translation occurs in viroplasm (combo of viral and cellular components and lipids).

41
Q

Which virus that produces viral gastroenteritis is one of the few viruses that produces toxin?

A

rotovirus

42
Q

Why does infection with rotovirus lead to diarrhea and dehydration?

A

virus infects tips of villi in small intestine

infected cells are lysed by new virus

immature epithelial cells have reduced absorptive capacity (sugar, salts, water)

fluid accumulates in lumen

diarrhea and dehydration

43
Q

Rotavirus non-structural protein 4 (NSP4) is released from infected and stimulates enterochromaffin cells (ECs, one type of enteroendocrine cell) to release 5- hydroxytryptamine (5-HT)15, a neurotransmitter that regulates gastrointestinal motility and induces nausea and .

A

enterocytes

vomiting

44
Q

acute diarrhea lasts?

persistent diarrhea lasts?

chronic diarrhea lasts?

A

acute= 0-13 days

persistent= 14-29

Chronic = 30 +days

45
Q

What 3 organisms or biological agents are mainly associated with vomiting?

A

preformed toxins

enteric viruses

nematodes

46
Q

Which 7 pathologic agents are associated with watery diarrhea?

A

enteric viruses

c. perfingens
c. diff

vibrio species

enterobacteriaceae

protozoa

tapeworms

47
Q

Which 4 infectious agents are involved with inflammatory diarrhea (fever, mucoid, bloody)?

A

enterobacteriaceae

campylobacter spp

entamoeba histolytica

noncholera vibrios

48
Q

Enteric viruses can be involved with both vomiting and diarrhea

A

watery diarrhea

49
Q

Enterobacteriaceae can be associated with both watery diarrhea and diarrhea

A

inflammatory diarrhea (fever, mucoid, bloody)

50
Q

Which diarrheal type is associated with usually being self-limited, enteric viruses?

A

acute diarrhea (0-13 days)

51
Q

What diarrheal length type is associated with protozoal infection?

A

persistent diarrhea (14-29 days)

52
Q

Which diarrheal length type can be associated with immunocompromised?

A

chronic diarrhea (30+ days)

53
Q

Which 2 enteric pathogens are associated with high fever and which is associated with afebfrile?

A

high fever= bacterial etiology, E. histolytica

afebrile= STEC (Shiga toxin producing E coli)

54
Q

What pathogen is associated with watery diarrhea, vomiting, abdominal cramps, and fever?

Incubation 6 h - 2 days

Duration 48h- 7 days

A

Salmonella

55
Q

What pathogen is associated with watery diarrhea, vomiting, abdominal cramps, and fever?

Incubation: 1-2 days

Duration: weeks

A

Enteropathogenic E. Coli (EPEC)

56
Q

Which pathogens are associated with fever?

A

Salmonella

campylobacter

shigella

yersinia enterocolitica

enteropathogenic E. Coli (EPEC)

Enteroinvasive E. Coli (EIEC)

57
Q

Which 2 E. Coli types are associated with watery diarrhea and and which 2 with bloody diarrhea?

A

watery- enteropathogenic (EPEC), enterotoxigenic (ETEC)

bloody- Enterohaemorrhagic (EHEC), Enteroinvasive (EIEC)

58
Q

EPEC, ETEC, EHEC, and EIEC are all associated with diarrhea and .

A

vomiting

59
Q

Which enteric pathogen is most associated with children 6-18 mnths?

Birth to 3 months and age over 50 and a history of atherosclerosis?

1-7 yrs old?

young adults?

A

rotavirus -6 to 18 mnths

nontyphoidal Salmonella- Birth to 3 months and age over 50 and a history of atherosclerosis

shigella- 1-7 yrs old

campylobacter- young adults

60
Q

Immunocompromised people are most at risk for which 5 enteric pathogens?

A

Salmonella, Cryptosporidium, Campylobacter, Shigella, Yersinia

61
Q

What 2 enteric pathogens are associated with hemochromatosis or hemoglobinopathy?

A

Y. enterocollitica and Salmonella

62
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76
Q

What level of infectious dose?

Shigella

STEC

Norovirus

Rotovirus

Giardia

Cryptosporidium

A

low infectious dose (<500)

77
Q

What level of infectious dose?

Salmonella

Campylobacter jejuni

A

Moderate infectious dose

78
Q

What level of infectious dose?

Enteroinvasive E. Coli

Enterotoxigenic E. Coli

Enteropathic E. Coli

Vibrio Cholerae

A

high infectious dose

79
Q

Review

A
80
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81
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ICOM- GI system (12 decks)

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