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Flashcards in Infectious Diarrhea Deck (36):
1

4 aspects of patient history very relevant to determining cause of (infectious) diarrhea?

Travel
Recent hospitalization
Diet
Medications
Medical history (esp immunocompromised)

2

5 signs/symptoms that make diarrhea merit further investigation?

Fever >103F.
Tenesmus
Bloody diarrhea
Prolonged course (>2 weeks)
Dehydration

3

What is tenesmus?

Feeling the urge to pass stool despite bowels being empty.
It is indicative rectal / colon inflammation.

4

5 host factors that increase susceptibility to infectious diarrhea?

Reduced gastric acidity.
Less gastric mucus.
Slowed GI motility
Alterations in gut flora (i.e. ABx)
Systemic and local immune deficiency

5

4 things that bacterial virulence factors can be / promote?

Adhesion
Entertoxins
Cytotoxins
Mucosal invasion

6

What do Cholera enterotoxins A and B do?

A: hits surface epithelium, blocks electrolyte absorption.
B: hits crypts, increases Cl- excretion via cAMP (the one we've heard about)

7

What do C. diff cytotoxins do?

Decrease cell-cell adhesion -> electrolyte and water leakage.

8

Diarrhea + fever in adult probably means? In children?

Adults: probably invasive pathogen
Children: probably rotavirus

9

If you've got non-bloody infectious diarrhea, what's the most likely class of organism responsible?

Viruses
(then bacteria, then parasites)

10

What are the 5 most common viruses causing non-bloody diarrhea?
For which do we have a vaccine?

Calcivirus (Noro and Norwalk-like virus)
Rotavirus - we have vaccine
Adenovirus
Astrovirus
Torovirus

11

4 most common organisms causing food-borne, non-bloody bacterial diarrhea?

Enterotoxigenic E. coli (ETEC)
Diffusely adhering E. coli
V. cholera
other Vibrio

12

3 most common organism causing non-food-borne, non-bloody bacterial diarrhea?

Aeromonas
Bacteroides fragilis
Diffusely adhering E. coli

13

2 parasites causing non-bloody diarrhea (that you actually ever hear about)?

Giardia and cryptosporidium

14

Which E. coli causes bloody diarrhea? What does it make?

Enterohemorrhagic E. coli (EHEC)
It makes Shiga toxin.

15

What do Shigella, Salmonella, Campylobacteria, C. diff, E. histolytica, and Schisto all have in common?

They all cause bloody diarrhea.

16

Broadly, most things that cause tenesmus / proctitis are what? 5 examples? 1 exception?

Are STDs: N. gonorrhea, T. pallidum, Chlamydia, HSV 2.
Exception: Shigella

17

What do C. perfringens, S. aureus, B cereus, C. botulinum, and B. anthracis have in common?

All can cause food-bone diarrhea through their toxins.

18

What do microsporidia, cryptosporidium, cyclospora, isospora, mycobacterium avium complex (MAC), and strongyloides have in common?

Cause non-bloody diarrhea in immunosuppressed patients.

19

What 2 viral organisms cause bloody diarrhea in immunosuppressed patients?

CMV and HSV.

20

Most common type of organisms responsible for traveler's diarrhea?

Bacteria, specifically ETEC (and EAEC)

21

What is the definition of diarrhea in a hospitalized patient?

Diarrhea that starts 3 days after admission.

22

Diarrhea in a hospitalized patient is pretty much always what?

C. diff.

23

What can you test for in the stool to get a vague idea of whether or not diarrhea is inflammatory? (2 molecules)

Lactoferrin and calprotectin

24

Is testing for fecal leukocytes very useful?

They're only usually present in a very small number of infections.

25

What additional tests do you do on an immunocompromised patient with diarrhea?

Stool cultures for microsporidia, isospora, etc.
Colonoscopy, upper endoscopy for CMV and MAC lesions.

26

Extra tests for evaluations of Traveler's diarrhea?

Test stool for...
Aeromonas
Ova and parasites, depending on region traveled to.

27

Micro review: What does C. diff look like on colonoscopy?

Psuedomembranous colitis

28

Among Giardia, Cryptosporidium, Plesiomonas, and Yersina, which is most like to cause food-borne bloody diarrhea in a healthy 20 year old?

Yersinia...
(This is a poor question, as Plesiomonas and Yersinia aren't among the more common diarrhea-causing organisms. But you should know that giardia = contaminated (beaver pond) water, and crypto = immunocompromised.)

29

2 viruses that can cause chronic diarrhea?

CMV, HSV

30

3 parasites that can cause chronic diarrhea?

E. histolytica, strongyloides, schisto

31

Two causes of chronic absorptive infectious diarrhea?

Whipple's disease: Tropheryma whipplei
Giardia
(FYI, the yearly incidence of Whipple's disease is 1 per 1,000,000.... so...)

32

When somebody has chronic diarrhea, what do you first test for?

Non-infectious things: Celiac Abs, TSH, metabolic panel.
And a CBC.

33

What are the preliminary stool tests that should be done for chronic diarrhea? (4 things)

C. diff
Ova and Parasites (Crypto and Giardia)
Culture for Aeromona
Qualitative fecal fat

34

What do high eosinophils in CBC suggest about cause of chronic diarrhea?

Parasite - guy in the case had schisto

35

Which viral diarrhea do you treat?

CMV

36

What bacterial diarrhea do you definitely not want to treat? Why not?

EHEC
Doesn't help, and increases risk for hemolytic-uremic syndrome (HUS).