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PCM Exam 4 > GI Infections 5 > Flashcards

GI Infections 5 Flashcards

1
Q

if the patient is only positive for the antibodies to HBs antigen, it is indicative of ______

A

vaccinated against HBV

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2
Q

what are some incriminated foods for contamination by the B. cereus emetic toxin

A

rice

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3
Q

_______ has a bacteriophage encoded enterotoxin

A

Vibrio cholera

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4
Q

what are some common pathogens in the Enterobacteriaceae family?

A
  • E. coli
  • Shigella
  • Salmonella
  • Yersinia
  • Klebsiella
  • Proteus
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5
Q

pt. has negative surface antigen positive antibodies for surface antigen and has positive iGG for HBc

A

previous exposure

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6
Q

vibrio cholera has a ______ encoded enterotoxin

A

bacteriophage

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7
Q

_________ is an E. coli plasmid encoded enterotoxin that has similar function as that of the Cholera toxin

A

LT enterotoxin

cholera = activates adenylate cyclase

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8
Q

the B subunit binds to ______ on the cell surface

A

GM1 receptor

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9
Q

what is the difference between the enterotoxin released by E. coli and that released by Vibrio cholera?

A
  • both cause watery diarrhea
  • both are AB enterotoxins that bind to GM1 receptor
  • E. coli is PLASMID encoded
  • Vibrio cholera is BACTERIOPHAGE encoded
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10
Q

which E. coli strain does NOT have LT or ST or CFA? how does it cause watery diarrhea?

A
  • EPEC (enteropathogenic)

- via effacement of the microvilli in the SI

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11
Q

incubation period of someone who just ingested a preformed exotoxin in food:

A

within hours of eating the food

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12
Q

why is ingestion of antacids a risk factor for developing vibrio cholera infection?

A

vibrio cholera is acid sensitive so by ↑ the pH of the stomach, then it makes it more likely for the bacteria to survive

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13
Q

describe the structure of the enterotoxins released by E. coli and how they attach

A

it is a 1A5B toxin (5 peripheral B subunits all attached to one central A subunit)
B subunit binds to GM1 receptor and the A subunit enters the cell and causes the ↑ in cAMP or cGMP

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14
Q

clostridium perfringens is associated with _________ (food)

A

meat dishes/gravy that have been left out after being heated

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15
Q

Vibrio Cholera is oxidase _______

A

POSITIVE (E. coli is oxidase negative)

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16
Q

after adhesion, E. coli releases two plasmid-encoded _________:

A

enterotoxins:
LT: activates adenylate cyclase (similar to cholera)
ST: activates guanylate cyclase

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17
Q

vibrio cholera is a +/- sucrose fermenter

A

+

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18
Q

what is the mechanism of the ST (heat stable) enterotoxin released by E. coli?

A
  • activates guanylate cyclase
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19
Q

what is the difference between C. perfringens and B. cereus in terms of enterotoxin production

A
  • C. perfringens only produces the toxins once it is inside the SI
  • B. cereus can produce the toxin while in the food so you can ingest the toxin but not for C. perfringens
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20
Q

the cholera toxin is similar to the ______ enterotoxin of E. coli

A

LT (↑ cAMP)

21
Q

what kind of enterotoxin is produced by C. perfringens?

A

LT (CPE)

22
Q

what are some unique features of EPEC?

A

EPEC does NOT have ST or LT or CFA

EPEC has a large adherence factor plasmid that encodes for bundle forming pili

23
Q

describe the biology of clostridium perfringens

A
  • gram postive
  • large anaerobes
  • non motile
  • ubiquitous in nature
  • spore forming
24
Q

E. coli has a ________ encoded enterotoxin

A

plasmid

25
Q

what is the mechanism of the cause of non inflammatory diarrhea

A

colonization and release of enterotoxin in SI

26
Q

what is the cause of the emetic type of bacillus cereus infection

A

ingestion of food containing PREFORMED ST NEUROTOXIN

27
Q

the H antigen in E. coli makes up the ______

A

subunits of the bacterial flagella

28
Q

gram negative rod that ferments sucrose and mannose but NOT arabinose

A

Vibrio cholera

29
Q

how does EPEC colonize and adhere to the SI when it does not have CFA?

A

EPEC strains carry a large EPEC adherence factor plasmid that encodes bundle forming pili (BFP)
then it effaces the microvilli → loss absorptive surface → watery diarrhea

30
Q 
describe the biology of E. coli 
catalase: 
oxidase: 
agar: 
does it ferment lactose?
A
  • gram negative bacilli
  • facultative anaerobe
  • member of normal (commensal) intestinal flora
  • catalase positive
  • oxidase negative
  • lactose fermenter
  • grown on MacConkey agar
31
Q

how does C. perfringens cause watery diarrhea?

A
  • sporulation in the SI
  • release of CPE (C. per fringes enterotoxin/ LT)
  • cytotoxic activity in which there is pore formation in the membrane
32
Q

metabolic ________ is a common result of diarrhea

A

acidosis due to the loss of HCO3

33
Q

__________ is a bacteria that has cytotoxic activity and causes pore formation leading to watery diarrhea

A

C. perfringens

34
Q

describe the biology of Vibrio cholera
motile?
spore forming?
oxidase activity?

A
  • single curved gram NEGATIVE rods
  • ”s” shaped
  • motile with a single polar flagellum
  • non spore forming
  • oxidase POSITIVE
35
Q

which E. coli strain is also known as “infantile diarrhea”

A

EPEC

ePec: Pediatrics

36
Q

what is a screening method for cholera in stool samples?

A
  • look for oxidase activity because E. coli does not have oxidase activity while Cholera does
37
Q

TCBS agar is used for what pathogen?

A

Vibrio cholera

38
Q

_____ is grown in MacConkey agar

A

E. coli

it is a selective media

39
Q

strains of Vibrio cholera are classified based on ______

A

O and H antigens

O1 and O139 are most important

40
Q

describe the biology of bacillus cereus

A

gram positive
arranged in chains
aerobic
has both emetic toxin and enterotoxin

41
Q

where can you find bacillus cereus

A

air, soil, water, and dust

42
Q

which species of E. coli is the #1 cause of traveller’s diarrhea?

A
  • ETEC (enterotoxigenic E Coli)
43
Q

how does E. coli attach to and colonize the SI?

A

-CFA: colonization factor antigens = fimbrae

44
Q

what is the neurotoxin that is ingested from contaminated rice in ______ infection

A

ST neurotoxin in B. cereus infection causing emesis

45
Q

Vibrio cholera can be grown on _________ agar with ______ as the differentiating agent

A
  • thiosulfphate citrate bile salts sucrose (TCBS) agar

- SUCROSE is the differentiating agent → yellow color because cholera ferments sucrose

46
Q

viral infection usually causes ______ diarrhea

A

non inflammatory

47
Q

bundle forming pili is a virulence factor for _____

A

EPEC

48
Q

what is the diarrhea enterotoxin in bacillus cereus

A

LT (↑ cAMP)

49
Q

fecal leukocytes are NOT found in inflammatory/noninflammatory diarrhea

A

non inflammatory diarrhea

PCM Exam 4 (44 decks)

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