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Medicine II: Infectious Disease > GI Infections > Flashcards

GI Infections Flashcards

1
Q

Most common bacterial causes of acute diarrhea

A

salmonella, shingella, campylobacter, E. coli

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2
Q

Salmonella risk factors

A

antacid use, prior abx use, depressed immune function

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3
Q

How do we get Salmonella

A

contracted via contaminated food, mostly meat and milk products, undercooked chicken products.

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4
Q

Dx of Salmonella

A

monocytes in the stool (2+ PMNs) (RBCs-rare)

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5
Q

Salmonella

A

A aerobic gram neg. bacillus; motile, does not ferment lactose; acid sensitive

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6
Q

How and where does Salmonella infect?

A

attach to epithelial cells in SI and colon

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7
Q

Shingella

A

gram neg bacillus, nonmotile, does not ferment lactose

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8
Q

How and where does Shigella infect?

A

surface proteins that induce cellular ingestion, uses surface hemolysin to lyse the phagosome membrane and escape into the cytoplasm where it induces actin rocket tails to propel it. First takes up residence in SI then invades colon.

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9
Q

Symptoms of Salmonella

A

can cause bacteremia, enters mesenteric LN and causes classic enteric fever

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10
Q

How does Shigella spread?

A

cell to cell, produces cytotoxic Shiga toxin and induces premature cell death (does not enter the blood stream)

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11
Q

Which cause of acute infectious diarrhea is acid resistant?

A

Shigella

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12
Q

How is Shigella transmitted?

A

fecal oral route (only in humans); children in day cares have high incidence of infection

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13
Q

Campylobacter

A

commoa shaped gram neg rod; paired in a seagull shape. ACID SENSITIVE

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14
Q

How and where does Campylobacter infect?

A

Ingested by monocytes, surviving in the gut for 6-7 days. Once intracellular it induces cell death and tissue necrosis and intense inflammatory reaction which allows it to enter the blood stream.

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15
Q

How is Campylobacter transmitted?

A

It commonly infects poultry (10x more common in chicken than Salmonella)

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16
Q

ETEC pathology

A

enterotoxigenic strains of E. coli. Colonize the small bowel and produce a cholera like or heat stable toxin.

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17
Q

ETEC is found

A

in developing countries: water is contaminated w/ human sewage

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18
Q

ETEC diarrhea

A

stimulates secretion of chloride, causing watery diarrhea

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19
Q

ETEC tx

A

Ciprofloxacin or Levofloxacin

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20
Q

Which E coli is a main cause of travelers diarrhea?

A

EHEC

21
Q

EHEC pathology

A

produces verotoxins or shiga like cytotoxins that inhibit protein synthesis and cause cell death

22
Q

EHEC is found

A

in industrialized nations, associated with undercooked beef or unpasturized milk (Cattle is primary resevior)

23
Q

EHEC diarrhea

A

toxin damages endothelium in the bowel and glomeruli, causing hemorrhagic inflammatory colitis and hemolytic uremic syndrome

24
Q

EHEC Tx

A

no tx; avoid anti motility drugs (increase toxin release and worsen hemolytic uremic syndrome). Supportive Care ONLY

25
Q

V. Cholera toxin

A

gains entry to small bowel when host ingests contaminated water or food. (NEUTRALIZED BY STOMACH ACID) Attaches to small intestine and creates cholera toxin. Endotoxin binds to specific receptor in bowel mucosa that activates adenylate cyclase causing an increase in cAMP, elevated cAMP in turn promotes secretion of chloride and water causing voluminous watery diarrhea

26
Q

Rugose

A

a/w cholera. an aggregation of bacteria surrounded by a protective biofilm, that blocks killing by chlorine and other disinfectants

27
Q

Gastroenteritis

A

acute diarrhea (lasts less than 14 days), abdominal pain, diffuse pain and tenesmus

28
Q

Clinical manifestations of enteric fever caused by s. typhi and s. paratyphi

A

COME BACK

29
Q

Watery Diarrhea Etiologies:

A

ETEC and Vibrio

30
Q

Bloody Diarrhe Etiologies:

A

Shingella, Campylobacter, EHEC

31
Q

Tx of Shingella

A

Cipro

32
Q

Tx of Salmonella

A

Cipro

33
Q

Tx of Campylobacter

A

Azithro

34
Q

Tx of V. cholera

A

Cipro

35
Q

Tx of C. diffe

A

Metronidazole

36
Q

C. Diffe

A

spore forming, gram negative rod that produces watery diarrhea. Releases 2 toxins (A and B) that bind to and kill cells in the bowel wall. There is a third toxin, binary toxin, that is a/w severe disease.

37
Q

Pathogenesis of C. Diffe

A

Forms shallow ulcers and pseudomembranes seen on colonoscopy (or CT)

38
Q

C. Diffe is most associated with….

A

Abx diarrhea, specifically clindamycin

39
Q

How does C. Diffe spread?

A

Person to person

40
Q

Signs and symptoms of C. Diffe

A

crampy bilateral lower abdominal pain that is decreased after a BM, low grade fever, mild peripheral leukocytes, TOXIC MEGACOLON, thumbprinting is seen

41
Q

Dx of C Diffe

A

Cytotoxicity assay, ELIZA can detect toxin A and B

42
Q

What is the most common form of infectious diarrhea

A

Viral diarrhea

43
Q

What causes viral diarrhea?

A

The disease is caused primarily by four viral groups: 


Norovirus (“Norwalk”), Rotavirus, Enteric adenovirus 40, 41, Astrovirus. For these etiologies no PMNs found in stool.

44
Q

Norovirus Diarrhea

A

blunts intestinal villi, causes mild malabsorption, is resistant to chlorine, is spread by contaminated water (including swimming pools), and primarily infects adults

45
Q

Rotavirus Diarrhea

A

Causes lactase deficiency, and primarily infects infants. Resists hand washing. Peaks in winter

46
Q

Enteric adenovirus diarrhea

A

Infects infants and young children; peaks in summer months

47
Q

Astrovirus Diarrhea

A

Infects children in pediatric wards & elderly in nursing homes

48
Q

Tx for viral diarrhea

A

Self-limiting diseases; use supportive care w/ hydration

Medicine II: Infectious Disease (12 decks)

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