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Med 2 - Week 57 > Enteric Infections > Flashcards

Flashcards in Enteric Infections Deck (53)
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Define: secretory diarrhea
- what are the features?

- Watery diarrhea w/o fever or with minimal fever.
- Continues despite increasing intake of food and water
- mid abdominal pain


Define: Inflammatory diarrhea

- mucoid like diarrhea
- accompanied by fever
- may often be bloody and have WBC in the stool
- lower abdominal and rectal pain


Where does secretory diarrhea originate in the GI tract

small bowel


What are 5 examples of causative pathogens of secretory diarrhea?

1. Vibrio cholera
2. Rotavirus
3. E. coli (ST or LT)
4. Norovirus
5. Giardia


What are 5 examples of causative pathogens of inflammatory diarrhea?

1. Shigella
2. Campylobacter
3. E. coli (EHEC/STEC)
4. Entamoeba histolytica
5. C. difficile


What are the two toxins that C. diff produces? Which is more pathogenic?

Toxin A (enterotoxin) and B (cytotoxin)
- Toxin B is more pathogenic


What are 2 medication types that increase risk for C. diff?

1. broad spectrum antibiotics

2. PPIs


What is the diarrhea like with C. difficile?

watery and foul smelling (like a barn)


What is the leukemoid reaction?

phenomenon of an increase in WBC count that mimics leukemia but is due to infection
- common in C. diff


What is the treatment approach for C. diff?

1. Stop unnecessary antibiotics
2. Metronidazole (IV or oral) and Vancomycin (oral only)
3. Stool transplant to replenish to replenish microbiota


what are 3 virulence factors that pathogenic E. coli have?

1. Fibriae: allow for colonization

2. Adhesions: allow for cell invasion

3. Toxins: both endo and exo


Shiga toxin is an example for what kind of toxin?

Exotoxin = secreted


What is ETEC and what specific pathogenic adaptations does it have?

Enterotoxigenic E. coli

1. fimbriae for attachment
2. Heat labile (LT) toxin similar to cholera
3. heat stable toxin (ST)


What is the clinical syndrome for ETEC diarrhea?

mild water diarrhea and nausea but no vomiting for 1-4 days


What is the pathogenesis of ETEC diarrhea?

ingestion of fecally contaminated food/water with 10^8-10 bacteria needed to cause disease


What is the treatment for ETEC diarrhea?

Oral rehydration


What are EHEC and STEC?

They're the same thing

enterohemorrhagic e. coli and shigatoxin producing e. coli


What are the virulence factors specific to EHEC/STEC

The shiga toxin (A/B) toxin
- acts on ribosomes to block protein synthesis leading to cell death
- has preference for enterocytes and endothelial cells in the kidney


What is the clinical syndrome of EHEC/STEC?

vomiting, diarrhea (often bloody), and abdominal pain

for children: 5-10 days later can develop lethargy, anemia, oliguria = hemolytic uremic syndrome


What are the two forms of salmonella?

non-typhoidal and typhoidal


What are the forms of non-typhoidal salmonella? What kind of illness do they cause?

Enteritidis and thyphimurium
- usually not invasive, self resolving disease


What are the forms of typhoidal salmonella? What kind of illness do they cause?

Typhi and parathyphi
- cause invasive disease with fever and bacteremia which is fatal if not treated


what are the typical reservoirs of non-typhoidal salmonella?

reptiles and chickens


What is the clinical picture of non-typhoidal salmonella?

Acute diarrhea with fever and abdominal pain that resolves within 4-7 days


What is the reservoir of typhoidal salmonella?

human only


What are the clinical symptoms of typhoidal salmonella disease?

Not always diarrhea! Can be constipated
- can lead to ileus and perforation

Long fevers + rash, headache


Where can salmonella typhi reside in the body dormant

the gallbladder


What is the virulence factor of typhoidal salmonella?

Vi capsular antigen which prevents phagocytosis


What is the treatment for typhoidal salmonella?

antibiotics based on local resistance


What are 3 adaptations that H. pylori have to increase colonization in the stomach ?

1. urease: converts urea to ammonium to neutralize stomach acid
2. swimming ability: spiral shape + flagella
3. Adhesions to bind to epithelial receptors