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Flashcards in Acute Diarrhea/GI infections Deck (70):
1

Where are most nutrients absorbed?

the proximal 100-150 cms

2

Features of small bowel infection

watery diarrhea, large volume, abd cramping, bloating, gas, wt loss
fever is rare
rare stool WBCs or occult blood

3

Features of large bowel infection

frequent small regular stools
painful BM or tenesmus
fever
bloody, mucoid stools
RBCs and WBC on stool smear

4

What is the most common etiology of severe community acquired diarrhea?

87% bacterial

5

Define osmotic diarrhea

neither SI nor LI can maintain an osmotic gradient
electrolyte absorption is not impaired
osmotic gap is present (>100 mosm/kg)

6

Features of osmotic diarrhea?

can occur due to ingestion of poorly absorbed ions or surgars or sugar alcohols
disappears w/fasting (ie/at night) or cessation of offending substance
monosaccharides but not disaccharides can be absorbed intact across the apical membrane of the intestine

7

Define secretory diarrhea

small osmotic gap (<50 mosm/kg)
osmolality of colonic fluid contents is in equilibrium with body fluids

8

Features of secretory diarrhea?

can be causes b either net secretion of anions or inhibition of net sodium absorption, enterotoxins, peptides produced by endocrine tumors

9

How is the osmotic gap calculated?

2x([Na+]+[K+])
osmotic gap=serum osm - est stool osm
(normal ~290)

10

What does it mean when the osmotic gap is negative?

poorly absorbed multivalent anion (ie/phosphate or sulfate)

11

What are signs of surreptitious laxative ingestion?

chemical or chromatographic analysis of stool water
large osmotic gap (suggests magnesium ingestion)
negative osmotic gap
-eating disorders, munchausen, secondary gain (disability)

12

What are signs that a stool sample may have been tampered with?

if stool osmolarity extremely high-diluted with urine
if stool osmolarity extremely low-diluted with water

13

What is the number one foodbourne disease in the us? What are features of this pathogen?

salmonella typhi
gram negative encapsulated bacilli
found in poultry, eggs and milk, associated with pet turtles

14

What type of bacteria is shigella?

gram negative bacilli
unencapsulated, facultative anaerobes

15

Where is shigella commonly contracted?

daycare and institutional settings or person to person

16

What is the clinical course of shigella?

check for when trying to dx chrons
self limited
usually affects left colon, maybe ileum too
rarely causes HUS< seizures or reactive arthritis

17

What are key features of campylobaer jejuni?

leading cause of acute bacterial diarrhea worldwide
undercooked poultry, unpasteurized milk, conaminated water
incubtion up to 8 days
flu like prodrome
self limited
watery or hemorrhagic diarrhea
small and large bowel symptoms
reactive arthritis/erythema nodosum
guillain barre syndrome
pseudoappendicitis

18

Features of giardia lamblia?

drinking from mountain streams
acute or chronic diarrhea with upper abdominal bloating
small bowel disease
flagellated protzoan

19

Escherischia coli types?

ETEC (enterotoxigenic e coli)
EIEC (enteroinvasive e coli)
EAEC (Enteroaggregative ecoli)
EHEC (enterohemorrhagic e coli)

20

What is the principal cause of traveler's diarrhea?

ETEC

21

What 2 toxins does ETEC produce?

heat labile & heat stable (LT & ST)

22

What are key features of EHEC?

aka 0157:H7
undercooked ground beef
39% of cultured pathogens in visibly bloody specimens
associated w/HUS
potentially worse w/abx

23

Features of vibrio cholerae?

gram negative
contaminated drinking wter
seafood assoicated
worry about after natural disasters
enterotoxin
choleratoxin causes disease: opens CFTR leading to more water in the lumen

24

Describe vibrio cholera infection

usually asymptomatic/mild
severe disease-watery diarrhea and vomiting
incubation 1-5 days
may lose up to 1L/hr

25

How common is norovirus?

half all gastroenteritis worldwide
from contamination or person to person
schools, cruise ships, etc

26

What is the leading cause of death worldwide?

rotavirus
-children bwn 6 and 24 mo most vulnerable
vaccines now available

27

What parasites frequently cause diarrhea?

ascaris lumbricoides
strongyloides
necator americanus and ancylostoma duodenale

28

What is the leading cause of iron deficiency anemia in the developing world?

necator americanus and ancylostome duodenale
(hookworms)

29

What are common causes of diarrhea in immunocomprimised hosts?

parasites-crytp, isospora belli, cyclospora, microsporia
bacteria-salmonella, campylobacer, shigella, mac
viral-cmv, hsv, adenovirus

30

What is the definition of nosocomial diarrhea?

new diarrhea at least 72 hours after admission

31

A history of fever directs the DDX to what causes?

invasive bacteria, enteric viruses, cytotoxic organism (C diff, Ent hist), ischemia, IBD

32

What does diarrhea within 6 hours of eating something indicate?

ingestion of a toxin
ie/staph aureus-potato salad, bacillus cereus-chinese food/rice

33

What does diarrhea within 8-14 hours of eating something indicate?

clostridium perfringens infection (toxin producing)

34

Diarrhea that began more than 14 hours after food ingestion indicates what?

viral or bacterial, non specific

35

When and how to order stool culture for ova and parasites?

when: 3 times, 3 consecutive days (24hrs apart)
order w/ persistent diarrhea >14 days
travel to mountainous regions
exposrue to daycare
immune comprimised
community waterbourne outbreak

36

How is infectious diarrhea treated?

oral rehdration (preferred, IV ok)
oral rehydration solution-has sal, citrate, bicarb, KCl, glucose & sucrose in water

37

How to dx EHEC?

need 3 of the following:
-bloody stool
-no reported fever
-WBC >10,000
-abdominal tenderness

38

What empiric antibiotics are used for travelers diarrhea?

fluoroquinolong or TMP-SMX

39

What are the indications for empiric antibiotics?

fever, bloody diarrhea, presence of occult blood in stool

40

When can antimotility agents be used for diarrhea? Which agents do you use?

if fever is absent and stools are not bloody
loperamid or diphenoxylate may be used

41

What is the risk with giving and antimotility agent?

can facilitate the development of HUS in EHEC

42

What are some general features of C difficile?

gram positive spore forming anaerobic bacteria
assoc w/use of clinda
cause of anti-biotic associated pseudomembranous colitis

43

What are risk factors for C diff?

recent abx use
age
duration of hospital stay
chemo
IBD
AIDS
gi surgery or g tube?
antacids?

44

How is Cdiff transmitted?

fecal-oral

45

What is the time it takes to go from Cdiff exposrue to symptoms?

2-3 days
(risk of contraction for weeks after abx though)

46

What toxins does C diff produce?

toxin A-enterotoxin
toxin B-cytotoxin

47

What is the clinical presentation for C diff?

bloody watery diarrhea
fever
abd pain
leukocytosis
pseudomembranous colitis
severe-toxic megacolon (stop having diarrhea, ominous sign) sepsis, colonic perforation, death

48

C diff presention?

wearing gloves
wash hands (not w/hand gel)
isolation gowns

49

What are the two mainstays of C diff tx?

metronidazole and vancomycin***

50

What is the rate of C diff recurrence?

10-35%

51

Options for tx for C diff recurrence?

switch from metronidazole to vancomycin
vancomycin taper
rifaximin chaser
fidaxomicin (lower recurrance, narrower spectrum than vanco)
probiotics ??
fecal transplant
IVIG (anti IgG anti-toxin A)

52

What is a common bacterial used as a probiotic for c diff?

sacchromyces boulardii

53

What is irritiable bowel syndrome?

chronic and relapsing abd pain, bloating, and changes in bowel habits including diarrhea nad constipation

54

What are lab findings in IBS?

normal cbc, lytes and LFTs

55

What criteria does a patient's symptoms have to fit to be IBS?

Rome III Criteria
3days sx/mo in the last 3mo w/2 or more of the follwoing
-improvement w/defecation
-onset associated w/change in freq of stool
-onset associated w/ a change in form (appearance) of stool

56

What is diverticular disease?

actually pseudodiverticular outpouchings of the colonic mucosa and submucosa
-occurs near where nerves and arterial vasa recta penetrate the inner circular muscle coat to create discontinuities in the muscle wall

57

Where does diverticular disease usually occur?

sigmoid colon

58

What occurs when diverticula become inflamed?

diverticulitis

59

What exacerbates diverticulosis?

diets low in fiber, which reduce stool bulk

60

What can occur with diverticular perforation?

formation of pericolonic abscesses, development of sinus tracts (fistula), and occasionally peritonitis

61

What are the symptoms of diverticular disease?

~20% develop symptoms
-intermittent cramping, continuous lower abdominal cramping, continuous lower abdominal discomfort, constipation and diarrhea

62

Features of acute appendicitis?

males
adolescents/young adults
luminal obstruction/fecalith
ischemic injury and stasis favors bacterial proliferation

63

Sx of acute appendicitis?

periumbilical pain that moves to RLQ
nausea, vomiting, low grade fever, mildly elevated white count
mcburney's sign

64

What causes ischemic colitis?

mucosal infartction
-hypotension
-arterial spasm
transmural infarction
-arterial thrombotic/embolitic occlusion

65

Where does ischemic colitis usually occur?

watershed zones (splenic flexure, sigmoid colon and rectum)

66

Features of ischemic colitis?

segmental and patchy distribution
hemorrhagic and ulcerated mucosa
self limited
resolves when inciting event resolves
older ppl, usually w/coexisting cardiac or vascular disease

67

What are the symptoms of acute transmural infarction?

sudden severe abd pain and tenderness
sometimes accompanied by nausea, vomiting, bloody diarrhea, or grossly melanotic stool

68

What cytokines do Th1 cells produce?

IFN-gamma

69

What cytokines do Th2 cells produce?

IL-4, IL-5, IL-13

70

What cytokines do Th17 cells produce?

IL-17