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GI Week 2 > Lecture 13: Infectious Diarrhea > Flashcards

Lecture 13: Infectious Diarrhea Flashcards

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?

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?

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?

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

What are causes on non-bloody parasitic diarrhea?

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?

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?

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)?

A
  1. gonorrhea
  2. treponema pallidum
  3. chlamydia
  4. herpes simplex 2
  5. shigella
25
Q

What are food-borne toxin mediated diarrhea?

A
  1. Clostridium perfingens
  2. Staph aureus
  3. bacillus cereus
  4. clostridium botulinum
  5. bacillus anthracis
26
Q

In immunosuppressed patients?

A
  1. nonbloody
    i. microsporidia
    ii. cryptosporidium
    iii. cyclospora
    iv. isospora
  2. bloody
    i. CMV
    ii. HSV
27
Q

If you have diarrhea that starts in the hospital, what do you look for?

A

C. diff

28
Q

What are the causes of traveler’s diarrhea?

A
  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
Q

How do you evaluate an immunocompromised patient with diarrhea?

A

Look for CMV

Also look for an “spor” types of parasites

30
Q

What are the three groups of patients?

A
  1. normal
  2. immunocompromised
  3. hospital acquired (just look for C diff)
31
Q

What causes bloody stool via pork (or meat)?

A

Yersinia

32
Q

What are not causes of bloody stool?

A
  1. giardia
  2. cryptosporidium
  3. plesiomonas
    All of them are watery
33
Q

How do you diagnose acute diarrhea?

A 
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
Q

What are the big 3 for diarrhea stool analysis?

A
  1. Salmonella
  2. Shigella
  3. Campylobacter
    Also can be
  4. Aeromonas
  5. Plesiomonas
35
Q

What are the causes of chronic diarrhea (inflammatory)?

A
  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
Q

What are the causes of malabsorptive/osmotic diarrhea?

A
  1. Tropheryma whipplei (Whipple’s)
    • systemic infection, followed by weight loss, neurologic symptoms, cardiac inflammation, hyperpigmentation, arthralgia
  2. Giardia
37
Q

What is the diagnostic criteria for Whipple’s?

A

Done by endoscopy
Lipid laden macrophages in histology
Darker area = Tropheryma whipplei

38
Q

What are the causes of SECRETORY chronic diarrhea?

A
  1. Cryptosporidium
  2. Cyclospora
  3. Microsporidia
  4. Isospora
39
Q

What is the diagnostic evaluation of chronic diarrhea?

A
  1. C. diff
  2. crypto + giardia (looking for osmotic)
  3. Culture = aeromonas
  4. Fecal fat (qualitative)
40
Q

If you see eosinophils in your CBC, what is the cause of diarrhea?

A

Parasitic (something with “spor” in it)

41
Q

What is an example of a case where you do NOT treat infectious diarrhea?

A

Enterohemorrhagic E. coli

Treatment with antibiotics may lead to hemolytic uremic syndrome (HUS)

42
Q

What do you do if you suspect EHEC?

A

Do not treat with antibiotics!

Hemolytic uremic syndrome

43
Q

What is the significance of hemolytic uremic syndrome?

A

HUS

Something that can occur as a result of antibiotic treatment of EHEC

GI Week 2 (15 decks)

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