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Acute Diarrhea/GI infections Flashcards

1
Q

Where are most nutrients absorbed?

A

the proximal 100-150 cms

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2
Q

Features of small bowel infection

A

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

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3
Q

Features of large bowel infection

A 
frequent small regular stools
painful BM or tenesmus
fever
bloody, mucoid stools
RBCs and WBC on stool smear
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4
Q

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

A

87% bacterial

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5
Q

Define osmotic diarrhea

A

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

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6
Q

Features of osmotic diarrhea?

A

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

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7
Q

Define secretory diarrhea

A

small osmotic gap (<50 mosm/kg)

osmolality of colonic fluid contents is in equilibrium with body fluids

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8
Q

Features of secretory diarrhea?

A

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

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9
Q

How is the osmotic gap calculated?

A

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

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10
Q

What does it mean when the osmotic gap is negative?

A

poorly absorbed multivalent anion (ie/phosphate or sulfate)

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11
Q

What are signs of surreptitious laxative ingestion?

A

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

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12
Q

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

A

if stool osmolarity extremely high-diluted with urine

if stool osmolarity extremely low-diluted with water

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13
Q

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

A

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

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14
Q

What type of bacteria is shigella?

A

gram negative bacilli

unencapsulated, facultative anaerobes

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15
Q

Where is shigella commonly contracted?

A

daycare and institutional settings or person to person

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16
Q

What is the clinical course of shigella?

A

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

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17
Q

What are key features of campylobaer jejuni?

A 
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
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18
Q

Features of giardia lamblia?

A

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

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19
Q

Escherischia coli types?

A

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

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20
Q

What is the principal cause of traveler’s diarrhea?

A

ETEC

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21
Q

What 2 toxins does ETEC produce?

A

heat labile & heat stable (LT & ST)

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22
Q

What are key features of EHEC?

A 
aka 0157:H7
undercooked ground beef
39% of cultured pathogens in visibly bloody specimens
associated w/HUS
potentially worse w/abx
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23
Q

Features of vibrio cholerae?

A 
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
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24
Q

Describe vibrio cholera infection

A

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

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25
Q

How common is norovirus?

A

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

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26
Q

What is the leading cause of death worldwide?

A

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

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27
Q

What parasites frequently cause diarrhea?

A

ascaris lumbricoides
strongyloides
necator americanus and ancylostoma duodenale

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28
Q

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

A

necator americanus and ancylostome duodenale

hookworms

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29
Q

What are common causes of diarrhea in immunocomprimised hosts?

A

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

30
Q

What is the definition of nosocomial diarrhea?

A

new diarrhea at least 72 hours after admission

31
Q

A history of fever directs the DDX to what causes?

A

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

32
Q

What does diarrhea within 6 hours of eating something indicate?

A

ingestion of a toxin

ie/staph aureus-potato salad, bacillus cereus-chinese food/rice

33
Q

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

A

clostridium perfringens infection (toxin producing)

34
Q

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

A

viral or bacterial, non specific

35
Q

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

A 
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
Q

How is infectious diarrhea treated?

A 
oral rehdration (preferred, IV ok)
oral rehydration solution-has sal, citrate, bicarb, KCl, glucose & sucrose in water
37
Q

How to dx EHEC?

A

need 3 of the following:

  • bloody stool
  • no reported fever
  • WBC >10,000
  • abdominal tenderness
38
Q

What empiric antibiotics are used for travelers diarrhea?

A

fluoroquinolong or TMP-SMX

39
Q

What are the indications for empiric antibiotics?

A

fever, bloody diarrhea, presence of occult blood in stool

40
Q

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

A

if fever is absent and stools are not bloody

loperamid or diphenoxylate may be used

41
Q

What is the risk with giving and antimotility agent?

A

can facilitate the development of HUS in EHEC

42
Q

What are some general features of C difficile?

A

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

43
Q

What are risk factors for C diff?

A 
recent abx use
age
duration of hospital stay
chemo
IBD
AIDS
gi surgery or g tube?
antacids?
44
Q

How is Cdiff transmitted?

A

fecal-oral

45
Q

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

A

2-3 days

risk of contraction for weeks after abx though

46
Q

What toxins does C diff produce?

A

toxin A-enterotoxin

toxin B-cytotoxin

47
Q

What is the clinical presentation for C diff?

A 
bloody watery diarrhea
fever
abd pain
leukocytosis
pseudomembranous colitis
severe-toxic megacolon (stop having diarrhea, ominous sign) sepsis, colonic perforation, death
48
Q

C diff presention?

A

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

49
Q

What are the two mainstays of C diff tx?

A

metronidazole and vancomycin***

50
Q

What is the rate of C diff recurrence?

A

10-35%

51
Q

Options for tx for C diff recurrence?

A 
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
Q

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

A

sacchromyces boulardii

53
Q

What is irritiable bowel syndrome?

A

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

54
Q

What are lab findings in IBS?

A

normal cbc, lytes and LFTs

55
Q

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

A

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
Q

What is diverticular disease?

A

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
Q

Where does diverticular disease usually occur?

A

sigmoid colon

58
Q

What occurs when diverticula become inflamed?

A

diverticulitis

59
Q

What exacerbates diverticulosis?

A

diets low in fiber, which reduce stool bulk

60
Q

What can occur with diverticular perforation?

A

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

61
Q

What are the symptoms of diverticular disease?

A

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

62
Q

Features of acute appendicitis?

A

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

63
Q

Sx of acute appendicitis?

A

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

64
Q

What causes ischemic colitis?

A 
mucosal infartction
-hypotension
-arterial spasm
transmural infarction
-arterial thrombotic/embolitic occlusion
65
Q

Where does ischemic colitis usually occur?

A

watershed zones (splenic flexure, sigmoid colon and rectum)

66
Q

Features of ischemic colitis?

A 
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
Q

What are the symptoms of acute transmural infarction?

A

sudden severe abd pain and tenderness

sometimes accompanied by nausea, vomiting, bloody diarrhea, or grossly melanotic stool

68
Q

What cytokines do Th1 cells produce?

A

IFN-gamma

69
Q

What cytokines do Th2 cells produce?

A

IL-4, IL-5, IL-13

70
Q

What cytokines do Th17 cells produce?

A

IL-17

GI (20 decks)

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