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GI/Liver > Lec 32 > Flashcards

Lec 32 Flashcards

1
Q

What does it mean if diarrhea < 24 hours after source?

A

means there is a preformed toxin

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2
Q

What 2 bugs will cause a diarrhea within 6 hours?

A
  • staph aureus

- B. cereus

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3
Q

What 2 bugs will cause a diarrhea within 6-24 hours?

A
  • C. perfringens

- B. cereus

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4
Q

What 3 organisms will cause vomiting within 1-6 hours?

A
  • staph aureus
  • B cereus
  • norwalk virus
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5
Q

What is the dominant symptom in things with a preformed toxin?

A

vomiting

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6
Q

What are our defenses against GI infections?

A
  • gastric acid secretion
  • gastric pH < 4
  • intact small bowel motility
  • intestinal microflora
  • secretion IgA and serum IgG
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7
Q

What is enteroadherence?

A

attachment and effacing adherence

pili serve as antigen which allows colonization

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8
Q

What is mech of enterotoxin?

A

can be pre-formed or not

toxin-receptor interaction increases intracellular signaling [cAMP, cGMP, Ca, etc]

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9
Q

What is acute bacterial dysentery?

A

diarrhea that is mucopurulent, bloody and accompanied by ab pain, fever, and leukocytosis
= enteroinvasive mech

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10
Q

What are 5 causes of acute bacterial dysentery?

A
  • salmonella
  • shigella
  • campylobacter
  • yersinia
  • clostridium perfringens
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11
Q

What is cytotoxic mech of bacterial infection?

A
  • inhibits protein synthesis and triggers inflammatory cascade
  • disrupts tight junctions and mitochondria
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12
Q

What is mucosal invasion mech of bacterial infection?

A

main mech for colon –> invade enterocyte and multiply intracellularly and get cell death

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13
Q

What are 2 mechs of shigella infection?

A
  1. adherence to mucosal surface w/ release of toxin

2. invasion of epithelial lining

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14
Q

What part of GI does shigella?

A

usulaly infects colon w/ some terminal ileum

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15
Q

What is classic presentation of shigella?

A

watery diarrhea then entero-invasion –> multiple small volume bloody mucoid stool

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16
Q

Can shigella cause bacteremia?

A

rarely

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17
Q

What is the action of vibrio cholera’s two enterotoxin subunits?

A

B unit = Binds enterocytes usually in proximal small bowel

A unit = Activates intracellular adenylate cyclase –> stimulate intestinal secretion

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18
Q

What is presentation of vibrio cholera?

A

severe watery diarrhea = rice water diarrhea; can present with shock

no inflammatory cells in stool

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19
Q

What part of GI does cholera infect?

A

upper small intestine; colon relatively unaffected

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20
Q

What are the 2 toxins of enterotoxigenic E coli?

A

heat labile toxin = similar to cholera toxin; activates adenylate cyclase

heat stable = activates guanylate cyclase

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21
Q

What is usually the source of enterotoxic e coli?

A

contaminated food and beverages

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22
Q

What is clinical presentation of enterotoxigenic e coli?

A

most common cause of travelers diarrhea

non-invasive, watery non-bloody non-purulent diarrhea; can have variable volume loss

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23
Q

What is mech of EColi 01:H157?

A

epidemic E coli; usual route of infection is infected meat

adheres to distal small bowel with shiga-like toxin that causes mucosal destruction and allows toxin to enter circulation

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24
Q

What part of GI does E Coli 01:H157 infect?

A

distal small bowel

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25
Q

What is the major illness that enterotoxigenic E coli 01:H157 causes?

A

hemolytic uremic syndrome = due to endothelial cell injury have localized prothrombic state in glomeruli; hemolysis of RBCs due to shearing in damaged vessels

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26
Q

What kind of food is usually the source of staph aureus?

A

food with egg products or cream that is not adequately refrigerated

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27
Q

What is typical presentation of staph aureus infection?

A

within 4-8 hours have upper GI symptoms; N/V followed by watery diarrhea and resolved in 24 hours

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28
Q

What is source of clostridium perfringens infection?

A

inadequately heated meat

29
Q

What is typical presentation of clostridium perfringens?

A

diarrhea within 8-24 hours that resolves spontaneously

30
Q

What is pathogenesis of C Diff?

A
  • may colonize colon in normal flora; when normal colonic flora is disturbed ie following antibiotic use it becomes pathogenic

releases toxins A and B –> destroy epithelium –> get pseudomembrane of dead leukocytes and mucosal cells

31
Q

What are the actions of CDiffs two toxins?

A

toxin A = initiates inflammatory process but is non-essential for infection

toxin B = cytotoxic and causes cellular damage and destruction

32
Q

What are risk factors for c diff infection?

A

antibiotic use - particularly clindamycin
hospital stay
increased age
PPI use

33
Q

What is clinical presentation of C Diff infection?

A

profuse watery non-bloody stools with crampy abdomen

leukocytes [WBC > 20k] in stool

34
Q

What are two potential complications of C Diff?

A

toxic megacolon
toxic colitis
associated with NAP1 strain = more severe

35
Q

How do you diagnose CDiff?

A

C Diff toxin in stool or sigmoidoscopy to show pseudomembranes

36
Q

What are the 5 Fs of salmonella?

A

fingers, food, feces, flies, fomites

37
Q

What part of GI is usually infected by salmonella?

A

terminal ileum

38
Q

What is invasive non-typhoid salmenollosis?

A

usually in terminal ileum; maybe colon

salmonella penetrates lamina propria then lymphatics and bloodstream –> can lead to septic arthritis, meningitis, endocarditis, osteomyelitis

= salmonella bacteremia

39
Q

What are some conditison predisposing to salmonella infection?

A
  • sickle cell
  • lymphoma/leukemia
  • AIDS
  • aschlorhydria –> PPI
  • UC
  • schitosomiasis
40
Q

What is the presentation of salmonella gastroenteritis?

A

after 6-48 hrs have N/V then ab cramps and bloody diarrhea that may last days and be accompanied by fever

41
Q

What happens in typhoid fever?

A

salmonella typhi invades small bowel mucosa, lamina propria, lymphatics, blood stream

have minimal intestinal symptoms early on –> diarrhea, bleeding, perforation

high fever, headache, toxemia, mental status change

42
Q

Where do you get pain in typhoid?

A

RLQ b/c organisms localize in peyers patches of ileum

43
Q

What is source of campylobacter?

A

farm animals; chickens; raw milk + eggs

44
Q

What is clinical presentation of campylobacter?

A

invades mucosa; asymptomatic or watery diarrhea or dysentery 1-3 days after ingestion

stool has fecal leukocytes / obvious blood

45
Q

How do you diagnose campylobacter?

A

stool culture

46
Q

What can yersinia mimi?

A

appendicitis or crohns ileitis = RLQ pain of acute onset

47
Q

What is source of yersinia?

A

food or pets

48
Q

What is clinical presentation of yersinia?

A

mucosal invasion –> diarrhea, RLQ pain

49
Q

What 6 bugs produce blood diarrhea?

A
  • shigella
  • salmonella
  • entamobea
  • e coli
  • c diff
  • yersinia
50
Q

What 4 bugs produce watery diarrhea?

A
  • viruses
  • vibrio
  • giardia
  • enterotoxigenic E Coli
51
Q

What is most comon cause of community acquire gastroenteritis?

A

rotavirus

52
Q

What is transmission of rotavirus?

A

fecal-oral, respiratory secretions, or contaminated surfaces

53
Q

What kind of virus is rotavirus?

A

double stranded RNA virus

54
Q

What is mechanism of rotavirus

A

destruction of mature enterocytes in proximal small intestine –> secretory diarrhea; decreased brush border enzymes

55
Q

What is clinical presentation of rotavirus?

A

watery diarrhea without inflammatory cells

lasts 3-7 days

56
Q

What are our defences against rotavirus?

A

virus specific but short lived IgA –> Ab increases with subsequent infection

57
Q

What type of virus is norovirus?

A

single stranded RNA

58
Q

What is most common cause of community acquired infectious diarrhea in adults?

A

norovirus

59
Q

What makes norovirus so infectious?

A

viral shedding can occur during asymptomatic and in post-symptomatic state

60
Q

What is pathogenesis of norovirus infection?

A

non invasive
causes reversible lesions in upper jejunum –> blunting villi, lose brush border enzymes –> osmotic loose watery diarrhea

lasts 12-60 hours

61
Q

Who classically gets giardia?

A

IgA deficient patients

62
Q

Where does giardia infect?

A

mucosa of duodenum and jejunum –> upper GI symptoms more common than diarrhea

63
Q

What is mech of giardia infection?

A

not enteroinvasive = adheres to small bowel and destroys tight junctions

watery diarrhea= non-bloody, no mucous

64
Q

What is clinical presentation of entameoba histolytica?

A

varies from asymptomatic to severe dysentery with bloody stools; crampy abdominal pain; can cause ameobic liver abscess

65
Q

What is pathogenesis of entameoba histolytica?

A

ingest cyst –> beomce trophozoites in bowel –> phagocytose RBCs and cause ulcers throughout large intestine

66
Q

What do you see on endoscopy with entameoba histolytics?

A

punched out ulcers = mimic UC

dense inflammatory granulomas = ameoboma

67
Q

How do you diagnose entameoba?

A

microscopic examination of fresh stool specimen for trohpozoites

68
Q

What is pathogenesis of cryptosporidium infection?

A

sprozoites attach to enterocytes along their microvilli –> watery/profuse diarrhea

diagnose by stool assya

GI/Liver (36 decks)

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