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GI Week 2 > Lecture 13: Infectious Diarrhea > Flashcards

Lecture 13: Infectious Diarrhea Flashcards

(43 cards)

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1
Q

What is acute infectious diarrhea?

A

Less than 4 weeks

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2
Q

What is chronic infectious diarrhea?

A

Greater than 4 weeks

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3
Q

History is key. What do we need to find?

A
  1. Characteristics of diarrhea (bloody/watery, osmotic?)
  2. child vs. elderly
  3. Travel history
  4. recently hospitalized
  5. Diet
  6. Medications
  7. Medical history (immunocompromised)
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4
Q

What things in the physical exam do we need to know?

A 
Temperature > 103
Tenesmus
Bloody diarrhea
Prolonged course of over 2 weeks 
If you have these 4 things, you need to have diagnostic testing with hospitalization
If not, you can treat symptoms
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5
Q

What is tenesmus?

A

Feeling like you have to go all the time but only a little comes out at a time
This is something that is characteristic of inflamed bowel

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6
Q

What are host factors for susceptibility for infection?

A 
Gastric acidity (less acidic = less protection)
Gastric mucus
GI motility (slower motility = more chance of infection)
Less intestinal microbial flora
Systemic and local immune system deficit
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7
Q

What are bacteria-virulence factors to watch out for?

A

Adherence
Enterotoxin
Cytotoxin
Mucosal invasion

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8
Q

What is the classic enterotoxin? MoA of cholera?

A

Cholera enterotoxin
Vibrio cholera produces cholera toxin A and B
Cholera toxin A and B do two things
1. On the villus, cholera toxin A increases cAMP activity (because toxin B binds to GM1 ganglionosides) which inactivates HCO3/Cl and H/Na antiports (so less ions coming into the cell/therefore less fluid coming in)
2. On the crypt side, A and B toxin defuses through and activates cAMP to increase secretion of Cl-, thereby secreting more fluid/ions
Therefore, cholera makes you both absorb less and secrete more
Cholera toxin B is NON-toxic whle cholera toxin A is what is responsible for cAMP upregulation

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9
Q

What is the MoA of C diff?

A

Cytotoxins A and B
Are endocytosed
Glycosylates Rho and weakens the tight junctions
This increases inflammation and activates macrophages/neutrophils to come over
Cytotoxins = cell death!
-direct cytotoxicity

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10
Q

What is the difference between enterotoxin and cytotoxin?

A 
Enterotoxin = toxin that changes function of cell but not cell death
Cytotoxin = toxin that kills cell (direct cytotoxicity)
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11
Q

What does fever suggest about acute diarrhea?

A
  1. commonly associated with invasive pathogens

2. could be rotavirus in kids

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12
Q

What does vomiting suggest?

A
  1. viral diarrhea
  2. common in cholera
  3. common with staph aureaus
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13
Q

What does bloody stools suggest?

A
  1. invasive and cytotoxin-producing pathogens
  2. suspect EHEC infection in absence of fecal leukocytes
  3. NOT with viral agents and enterotoxins producing bacteria
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14
Q

What are the most common causes non-bloody infectious diarrhea?

A

Most common type of diarrhea

  1. viruses (most common)
  2. bacteria
  3. parasites
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15
Q

What is the most common non-bloody virus infectious diarrhea?

A
  1. Calcivirus (norovirus, Norwalk-like virus)
  2. Rotavirus
  3. Adenovirus
  4. Astrovirus
  5. Torovirus
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16
Q

What are the clinical symptoms of norovirus?

A 
Very short (24-72 hours) SHORTEST
Diarrhea, vomiting, abdominal cramps
Fecal-oral
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17
Q

What are the characteristics of rotavirus?

A 
1. fecal oral
CHILDHOOD diarrhea
Tropics = all year round
Temperate = winter only
Vomiting followed by watery diarrhea
Duration = 5-7 days
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18
Q

What are the characteristics of adenovirus?

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A

Adenovirus causes diarrhea
Serotypes 40 and 41
Children less than 2 years and immunocompromised
Duration = 5-12 days LONGEST

19
Q

What bacteria are food-borne that lead to non-bloody diarrhea?

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A
  1. Enterotoxigenic E. coli (ETEC)
  2. Diffusely adhering E. coli
  3. Vibrio cholera
  4. Non-cholera vibrio
20
Q

What bacteria are non-food-borne that lead to non-bloody diarrhea?

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A
  1. Aeromonas
  2. Bacteroides fragilis
  3. Diffusely adhering E. coli
21
Q

What are causes on non-bloody parasitic diarrhea?

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A
  1. Giardia
  2. Cryptosporidium
  3. Cyclospora
  4. Trichella spiralis
  5. Dientamoeba fragilis
  6. Blastocystis hominis
  7. Strongyloides
22
Q

What are causes of BLOODY infectious diarrhea?

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A
  1. food borne bacteria
    i. Shigella
    ii. Salmonella
    iii. Campylobacter
    iv. Enterohemorrhagic E. coli (EHEC)
    v. Enteroinvasive E. coli
    vi. E. coli
  2. Non-food borne bacteria
    C. Difficile (rarely)
  3. Parasites
    -E. histolytica
    -schistosomiasis
23
Q

What is proctitis?

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A

An inflammation of the anus and the lining of the rectum

24
Q

What happens when you have proctitis and tenesmus, that are pseudo diarrhea (because low volume just increased frequency)?

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A
  1. gonorrhea
  2. treponema pallidum
  3. chlamydia
  4. herpes simplex 2
  5. shigella
25
What are food-borne toxin mediated diarrhea?
1. Clostridium perfingens 2. Staph aureus 3. bacillus cereus 4. clostridium botulinum 5. bacillus anthracis
26
In immunosuppressed patients?
1. nonbloody i. microsporidia ii. cryptosporidium iii. cyclospora iv. isospora 2. bloody i. CMV ii. HSV
27
If you have diarrhea that starts in the hospital, what do you look for?
C. diff
28
What are the causes of traveler’s diarrhea?
1. parasites i. giardia ii. E. histolytica iii. Cryptosporidium 2. Bacteria i. Ecoli (ETEC and EAEC) ii. Campylobacter iii. Shigella iv. Salmonella v. Aeromonas vi. Plesiomonas vi. Vibrio spp
29
How do you evaluate an immunocompromised patient with diarrhea?
Look for CMV | Also look for an “spor” types of parasites
30
What are the three groups of patients?
1. normal 2. immunocompromised 3. hospital acquired (just look for C diff)
31
What causes bloody stool via pork (or meat)?
Yersinia
32
What are not causes of bloody stool?
1. giardia 2. cryptosporidium 3. plesiomonas All of them are watery
33
How do you diagnose acute diarrhea?
``` Look for Fecal Leukocytes (fecal lactoferrin and calprotectin) -allows you to look for inflammation CBC Stool culture Stool ova and parasites (ELISA for giardia) Stool C diff ```
34
What are the big 3 for diarrhea stool analysis?
1. Salmonella 2. Shigella 3. Campylobacter Also can be 4. Aeromonas 5. Plesiomonas
35
What are the causes of chronic diarrhea (inflammatory)?
1. bacteria i. C diff ii. Aeromonas iii. Yersinia iv. Salmonella v. Campylobacter vi. Tuberculosis vii. Gonorrhea viii. Treponema pallidum ix. chlamydia 2. Viral i. CMV ii. HSV (proctitis) 3. Parasites i. E. hystolytica ii. Strongyloides iii. Schistosomiasis
36
What are the causes of malabsorptive/osmotic diarrhea?
1. Tropheryma whipplei (Whipple’s) - systemic infection, followed by weight loss, neurologic symptoms, cardiac inflammation, hyperpigmentation, arthralgia 2. Giardia
37
What is the diagnostic criteria for Whipple’s?
Done by endoscopy Lipid laden macrophages in histology Darker area = Tropheryma whipplei
38
What are the causes of SECRETORY chronic diarrhea?
1. Cryptosporidium 2. Cyclospora 3. Microsporidia 4. Isospora
39
What is the diagnostic evaluation of chronic diarrhea?
1. C. diff 2. crypto + giardia (looking for osmotic) 3. Culture = aeromonas 4. Fecal fat (qualitative)
40
If you see eosinophils in your CBC, what is the cause of diarrhea?
Parasitic (something with “spor” in it)
41
What is an example of a case where you do NOT treat infectious diarrhea?
Enterohemorrhagic E. coli | Treatment with antibiotics may lead to hemolytic uremic syndrome (HUS)
42
What do you do if you suspect EHEC?
Do not treat with antibiotics! | Hemolytic uremic syndrome
43
What is the significance of hemolytic uremic syndrome?
HUS | Something that can occur as a result of antibiotic treatment of EHEC

GI Week 2 (15 decks)

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