Gi - Dickinson - Secretory Diarrhea

Front 1

What bact. cause Secretory Diarrhea?

Back 1

Vibrio Cholerae
Vibrio parahaemolyticus
E.Coli (Enterotoxigenic, Enteropathogenic, Enteroaggragative)

Front 2

What are the 5 diarrhea classifications?

Back 2

Altered Motility, Osmotic, Secretory, Inflammatory, Malabsorption/Maldigestion

Front 3

Whats the most common cause of diarrhea?

Back 3

infectious agent

Front 4

What causes most foodborne illness is US?

Back 4

Norovirus

Front 5

Invasive orgamisms affect which: small intestine or lg. intetine?

Back 5

Lg intestine.

(sm. intestine = non-invasive)

Front 6

Whats the difference in the diarrhea created by a lg. intestine (invasive) vs. sm. intestine (non-invasive) bact?

Back 6

Lg. Intestine = small volume, bloody, mucoid, inflammatory, fever)

Sm. Intestine = nausea, vomiting, lg. volume watery diarrhea, (NO: blood, fever, inflamm)

Front 7

What are the possible causes of acute bacterial diarrhea?

Back 7

Toxigenic
Cytotoxic
Invasive
Adherent

Front 8

Define Toxigenic

Back 8

Enterotoxin = major or exclusive pathogenic mechanism
(ex. = cholera toxin)

Front 9

Define Cytotoxic

Back 9

A cytotoxin-induced acute inflamm and intestinal secretion

Ex = shiga toxin

Front 10

Define Invasive as a cause of acute bact. diarrhea

Back 10

Organism penetrates mucosal surface as primary event --> induces acute inflamm (enterotoxin or cytotoxin may be produced as well , ex = salmonella or shigella)

Front 11

Define Adherent as a cause of acute bact. diarrhea

Back 11

Organism adheres to mucosal epi and disrupts epi architecture --> dec. water absorption

Front 12

Difference between Intoxication and Toxin formed in vivo?

Back 12

Intoxication = pt injests pre-formed enterotoxin

Toxin formed in vivo = pt. ingests microbe that colonizes gut and secretes enterotoxin --> disease symptoms

Front 13

Whats the most common cause of food poisoning?

Back 13

staph. a.

Front 14

If a pt. ingests pre-formed bact. toxin, does the bact. colonize the gut?

Back 14

NO, no need for it to as the toxin will have its effects

Front 15

Vibrio cholera is what type of bact?

Back 15

Gram neg. Bacillus, Aerobic

(vs. Enterotoxigenic E.coli= Gram neg. ROD)

Front 16

What areas of the world is vibrio cholera still a problem?

Back 16

developing countries where breakdowns in infrastructure lead to contamination of water supplies

Front 17

What determines the types of vibrio cholera?

Back 17

the Serogroups ie types of O antigens in the cell wall:

O1 (=98% of cholera) and O139 (=Asian outbreak) are what we talked about

Front 18

What is the O antigen on vibro cholera?

Back 18

Part of the LPS (lipopolysarrharide) cell wall layer

Front 19

How does Cholera present clinically?

Back 19

Abrupt onset vomiting and diarrhea
Abd cramps
Copious water loss
Dehydration (sunken eyes, cheeks, dec. skin turgor, Hypovolemic shock and metabolic acidosis)
Remission/Death after 3-5 days

Front 20

Pathogenesis of Vibro Cholera?

Back 20

Human + Marine reservoir --> Lg dose needed for infection (b/c of gastric acidity) --> Vibrio colonize mucosal surface via pili --> Enterotoxin produced (by O1 and O139) --> 24-72 hrs post ingestion = Symptoms (massive outpouring of isotonic fluid = rice water stool with mucus, epi cells, lg. numbers of Vibrios

Front 21

In general, when do enterotoxins ie toxins produced inside body produce symptoms?

Back 21

24-72 hrs post ingestion

Front 22

Rice water stool = what type of infection?

Back 22

Vibrio Cholera

Front 23

Why is cholera self-limiting?

Back 23

Vibrio cholera shed with the epi cells they are attached to in 3-5 days

Front 24

Which transmembrane receptor does cholera use?

Back 24

CFTR = Cystic Fibrosis Transmembrane Regulator

Front 25

What steps are involved in Cholera using the CFTR regulator?

Back 25

Cholera enters Cytosol --> ADP ribosylates Gs-alpha --> Constitutive Activation of Adenylate Cyclase --> Inc. in cAMP --> Activation of protein kinase A --> Phosphorylation of CFTR --> chloride and water loss

TO REMEMBER: ADP - Adenylate - cAMP - Prot. Kinase A - CFTR - CL and water loss

Front 26

Inc. in cAMP with choler toxin leads to what?

Back 26

Inc cAMP = Active SECRETION of chloride and bocarb + water loss greater than whats reabsorbed in colon

Front 27

T/F: Cholera toxin also effects myenteric plexus

Back 27

TRUE

Front 28

How do we treat cholera toxin illness?

Back 28

Water and Electrolyte replacement (IV or Oral)

Tetracyclin (=reduces shedding)

Oral Rehydration packet

Front 29

How does oral rehydration work?

Back 29

SGLT1

Sodium and Glu are taken up by SGLT1, water follows them

Front 30

How do oral cholera vaccines work?

Back 30

Orally

Elicit mucosal secretory Abs (IgA) directed against LPS and CT-B subunit

Front 31

How long are you vaccinated for with cholera vaccine?

Back 31

6 months (80-85% protection)

Front 32

Where can we find vibrio parahaemolyticus?

Back 32

salt water or brackish water

LEADING cause of gastroenteritis assoc. with seafood consumption

Front 33

Is Vibrio Parahaemolyticus Invasive in the GI?

Back 33

No, it invades wounds

Front 34

What are the symptoms of Vibrio Parahaemolyticus?

Back 34

diarrhea, abd. cramps, nausea, vomiting, headache, fever, chills

Front 35

What toxins are produced by Vibrio Parahaemolyticus?

Back 35

TDH (Thermostable direct hemolysin

TRH (TDH-related hemolysin)

=Hemolytic, Cardiotoxicity, Enterotoxicity, Osmotic Lysis

Front 36

How does TDH and TRH cause osmotic Lysis?

Back 36

form pore in membrane --> osmotic lysis

Front 37

Whats the primary cause of traveller's diarrhea?

Back 37

Enterotoxigenic E. coli

(heat-labile enterotoxin works the same as cholera toxin)

Front 38

How is Enterotoxigenic E. coli classified?

Back 38

Via the type of Antigen ie O, H, K

Front 39

Incidence of Enterotoxigenic E. coli highest?

Back 39

Latin America
Asia
Africa

Front 40

How do we treat Enterotoxigenic E. coli?

Back 40

Hydration with sucrose-electrolyte solution

Front 41

How do we prevent Enterotoxigenic E. coli?

Back 41

Cholera vaccine effective 67% of time

Front 42

T/F: Enteropathogenic E. coli produces toxin

Back 42

FALSE

Front 43

Pathogenesis of Enteropathogenic E. coli?

Back 43

Non-invasive; adheres to mucosa via pili (fimbriae)

Disrupts microvilli by causing actin polymerization to form pedestal (=A/E lesions) --> rearrangement of actin cytoskeleton --> effacing lesions --> Type III secretion --> loss of absorptive surface area

Front 44

Which forms a pedestal?

ETEC (enterotoxigenic)
EPEC (enteropathogenic)
EAEG (enteroaggregative)

Back 44

EPEC

Front 45

Enteropathogenic E. coli (EPEC) causes diarrhrea mostly in what population?

Back 45

infants

(MAY see low grade fever and vomit)

Front 46

Enteroaggregative E. coli is seen in what types of countries?

Back 46

Developing

Front 47

What are the symptoms associated with Enteroaggregative E. coli?

Back 47

Persistent diarrhea (>14 days)

Watery, mucoid diarrhea with secretory diarrhea with low grade fever and little to NO vomit

Front 48

Pathogenesis of Enteroaggregative E. coli?

Back 48

Enterotoxins and Cytotoxins

Front 49

Whats a persistent cause of diarrhea in HIV pts?

Back 49

Enteroaggregative E. coli

Front 50

If you see Stacked brick pattern what should you be thinking?

Back 50

Enteroaggregative E. coli

Bact. aggregate b/c of a mucus secretion causing stacked brick pattern