bacterial gasteroenteritis Flashcards

Describe the epidemiology and pathogenesis of enterohemorrhagic E. coli. Distinguish the various forms of E. coli infections. Differentiate E. coli and Salmonella using culture media. Diagnose Salmonella infections Describe the clinical characteristics and epidemiology of cholera. Identify the mechanism of action of cholera toxin. Compare Campylobacter and E. coli infections. Characterize the microbial cause of ulcers.

1
Q

predominant aerobe in the gut

A

e coli

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2
Q

noninflammatory diarrhea

A

watery, large volume stools with no blood, pus or severe pain

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3
Q

inflammatory diarrhea

A

lower volume stools with blood,pain, pus and fever

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4
Q

enterotoxins cause

A

noninflammatory diarrhea

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5
Q

cytotoxins cause

A

inflammatory diarrhea

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6
Q

definition of coliform

A

lactose positive

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7
Q

fecal pathogens that are lactose negative

A

salmonella and shigella

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8
Q

gram negative rod, ferments lactose

A

e coli

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9
Q

red colonies on macConkey indicate

A

lactose fermentor

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10
Q

habitat of e coli

A

GI tract of vertebrates and soil/water contaminated with feces

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11
Q

virulence factors of e coli

A
Pili
Locus for Enterocyte Effacement
Type 3 Secretion System
LT/ST enterotoxins
Shiga Toxin
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12
Q

MOA of LT toxin

A

ribosylates adenylyl cyclase –> increases cAMP –> causes secretion of water and electrolytes –> diarrhea

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13
Q

MOA of ST toxin

A

increases cGMP –> increases cAMP –> causes secretion of water and electrolytes –> diarrhea

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14
Q

produces shiga toxin

A

enterohemorrgagic e coli (EHEC) (O157:H7)

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15
Q

MOA of shiga toxin

A

inhibits protein synthesism provokes apoptosis –> capillary thrombosis and mucosal inflammation –> hemorrhagic colitis

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16
Q

bad end result of shiga toxin

A

hemolytic uremic syndrome

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17
Q

primary resivoir of e coli (O157:H7)

A

cattle gut

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18
Q

most important early virulence factor of EHEC

A

type III seretion lesion causing attaching and effacing lesions

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19
Q

intense abdominal pain, bloody diarreha, no or slight fever

A

EHEC

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20
Q

ID of e coli (O157:H7)

A

lactose positive colonies that do not ferment sorbitol, then test for O157 and H7 antisera

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21
Q

sx of HUS

A

acute renal failure, hemolyic anemia and thrombocytopenia

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22
Q

What NOT to EVER do in EHEC infection

A

give antibiotics (releases shiga toxin)

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23
Q

remains extra cellular, attached by lesions and injects toxin by integreated bacteriophage

A

e coli EHEC

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24
Q

causes watery diarrhea in bottle fed infants in developing countries

A

Enteropathic E coli (EPEC)

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25
Q

causes “traveler’s diarrhea”

A

enterotoxigenic e coli (ETEC)

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26
Q

“traveler’s diarrhea” very similar to

A

cholera

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27
Q

pathenogenies of ETEC

A

activates adenylate cyclase or guanylyl cyclase –> activates CHTR –> induces hypersecretion –> diarrhea

28
Q

general treatmene of e coli infections

A

supportive - rehydration or electrolyte replacement. Antibiotics only in invasive disease

29
Q

leading cause of infant diarrhea and death in developing countries

A

shigella

30
Q

lactose negative gram negative rods

A

shigella

31
Q

resivoir of shigella

A

human GI tract

32
Q

virulance factor only found in shigella

A

neurotoxin endotoxin

33
Q

MOA of shigella neurotoxin

A

binds the 60S ribosomal subunit, inhibiting protein synthesis

34
Q

severe abdominal cramps, frequent painful passage of low-volume stools containing blood and mucus

A

shigella

35
Q

sudden onset of diarrhea with fever and bloody stools in kids

A

shigella

36
Q

invades colonic epithelial M cells, multiplies in cytoplasm and spreads cell to cell

A

Shigella

37
Q

treatment for shigella

A

hydration by mouth, antibiotics (sulfonamides, streptomycin)

38
Q

gram negative rods, lactose negative, faculative anareobes

A

salmonella

39
Q

pet reptiles can carry

A

salmonella

40
Q

virulence factors include enterotoxin and pathogenicity island

A

salmonella

41
Q

sudden onset of headache, chills, abdominal pain followed by n/v and severe diarrhea

A

salmonella

42
Q

most common strain of salmonella causing “food poisoning”

A

S enterica Typhimurium

43
Q

systemic salmonella poisoning

A

enteric fever

44
Q

pathogenesis of salmonella

A

adheres to mucosal epithelial cells and induces actin movement. engulfed into vaculole which is transported through the basal membrane to the lymphatics –> to liver spleen and bone marrow

45
Q

treatment of salmonella

A

fluid and electolyte replacement, and control of n/v. Cholramphenicol for enteric fever

46
Q

frontal headache, decrease in appetite, fever, constipation, flu-like sx

A

typhoid fever

47
Q

DOC for typhoid

A

chloramphenicol

48
Q

where do long-term carriers of typhoid carry the bug

A

gall bladder

49
Q

common with poor sanitation,improper sewage disposal or flood contaminated water supplies

A

Cholera

50
Q

short, curved, gram negative rods

A

V cholerae, or campylocater jejuni

51
Q

infects shellfish

A

vibrios

52
Q

rice water diarrhea with massive fluid loss

A

cholera

53
Q

v cholerae viriulance factor (main 2)

A

CT (AB5) toxin, priduction of mucinase

54
Q

MOA of cholera toxin

A

locks sdenylate cyclase into active state –> hyperproduction of cAMP –> pushes large amounts of electrolytes and water out of cells

55
Q

needs a large dose to become infectious and attaches (does not enter cell) to outside of intestinal surface

A

V cholerae

56
Q

treatment of cholera

A

rapid IV injection of bicarb in acute - oral fluid/electrolyte replenishment

57
Q

species of vibrio caused by shellfish

A

vulnificus/parahaemolyticus

58
Q

needs a massive bolus of bacteria to infect

A

camylobacter

59
Q

virulence factor of camplobacter

A

enterotoxin similar to cholera

60
Q

complication of campylobacter

A

Guillain-Barre

61
Q

how campylobacter can cause GB

A

anti-bodies of the lipo-oligosaccharide of C jejuni cross-react with peripheral nerve gangliosides

62
Q

causes stomach ulcers

A

H pylori

63
Q

slender, curved, gram negative rods with polar flagella

A

H pylori

64
Q

non stomach ulcer diseases that H pylori can cause

A

gastric adenocarcinoma and Gastric MALT lymphoma

65
Q

vurulance factor fo H pylori

A

produces urase, producting ammonia and raising the pH in the vicinity.

66
Q

dx for pylori

A

c-urea breath test

67
Q

treatment for h pylori

A

antibiotics with PPI