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Micro Exam 4 > Vibrio Cholera > Flashcards

Vibrio Cholera Flashcards

1
Q

Vibrio cholera Characteristics

A

GN curved rod, facultative anaerobe, extracellular, non-invasive, oxidase +, Halophilic, motile - flagella

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2
Q

Main risk factor of v. cholera

A

consumption of raw or improperly cooked oysters

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3
Q

Vibrio cholera biofilms are supported by

A

RbmA, Bap1, RbmC

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4
Q

What media should be used to culture v. cholera?

A

TCBS agar (Thiosulfate-citrate-bile salts-sucrose agar)

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5
Q

6 different O antigen types of v. cholera, the most prevalent types in the US are?

A

O1, O139, O141, O75

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6
Q

6 different O antigen types of v. cholera, the most types that cause epidemics are?

A

O1, O139

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7
Q

New strain of v. cholera are due to

A

lateral transfer of gene cassettes responsible for O-antigen biosynthesis

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8
Q

Newer strains of v. cholera are

A

more virulent bc they have a greater ability to produce cholera toxin

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9
Q

new strain of v. cholera resistant to 3rd generation Abx was found, it contains

A

2 super bug genes (Metallo beta-lactamase-1 and plasmid-mediated beta-lactamase-1)

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10
Q

Transmission of v. cholera is

A

BIMODAL

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11
Q

Explain the bimodal transmission of v. cholera

A
  • Hyperinfectious state: lasts up to 5hrs after passing the organisms, in epidemics there is person-to-person spread
  • Ingested from environment (food borne): requires a high infective dose
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12
Q

In epidemic situations, v. cholera is spread

A

person-to-person (w/in 5hrs) at low infectious doses

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13
Q

Risk factors for v. cholera?

A

Warm, raw shellfish, contaminated food/water (salt-water) - esp if consumed w/ bicarb

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14
Q

Reservoir for v. cholera?

A

zooplankton, humans

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15
Q

V. cholera’s virulence factors

A

TCP, CT-1, CT-2, MARTX

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16
Q

Mechanism of Toxin Co-regulated Common Pili (TCP):

A

ESSENTIAL for colonization, attachment site for CTX phage (a lysogenic phage that contains genes encoding the cholera toxin)

17
Q

Cholera Toxins-1/2 (CT-1 & CT-2) mechanism

A

heat-labile enterotoxin, CTX phage encoded (lysogeny); binds to Gm1 ganglioside–> catalyses inactivation of GTPase and leaving adenylate cyclase turned on –> high levels of cAMP –> hypersecretion of Cl- , bicarb and water (cause of DIARRHEA)

18
Q

CT-1/2 bind

A

Gm1 ganglioside

19
Q

CT-1/2 activate

A

adenylate cyclase and cAMP

20
Q

CT-1/2 cause

A

secretion of Cl-, HCO3-, H2O = Watery diarrhea

21
Q

Multifunctional-Autoprocessing Repeats-in-ToXins (MARTX) Mechanism

A

disrupts actin cytoskeleton –> either allows colonization to occur or reduces the functionality of the innate immune cells preventing clearance (May have a role in extra-intestinal survival)

22
Q

Host defense against v. cholera is primarily?

A

CD4 T-cell dependent & IgA

23
Q

V. cholera inhabits the

A

small intestines

24
Q

MARTX is related to

A

Clostridium difficile toxin B

25
Q

V. cholera - Incubation period:

A

1-5days

26
Q

Main Symptoms of v. cholera

A

Abrupt and rapidly progressing: afebrile, rice water stools, effortless vomiting, muscle cramps, poor skin turgor, “absent” peripheral pulse, low or unobtainable blood pressure, sunken eyes, wrinkled skin over fingers, cyanosis of finger tips, lips, tongue; sweet fishy odor

27
Q

What would lab values for Extreme dehydration look like:

A

Hypovolemic shock, hemoconcentration, K depletion, loss of bicarb, severe acidosis

28
Q

Without treatment the chance that this patient may die is?

A

60%

29
Q

Disease usually resolves in

A

1-3, but may last up to 7days

30
Q

V. cholera is a toxemia meaning:

A

V. cholera adheres to the small intestine producing CT enterotoxin

31
Q

CT-1/2 are heat-labile meaning

A

they are killed by proper cooking

32
Q

Diagnostic fecal exam would reveal

A

GN curved rods w/ flagella

33
Q

Serotyping

A

is essential

34
Q

Treatment of v. cholera should include

A

enteric isolation, administration of electrolytes and fluids (IV and oral)

35
Q

What treatments may shorten the duration/severity of v. cholera?

A

Zinc and amylase-resistant starch (decreased fluid loss)

36
Q

Mechanism for amylase-resistant starch

A

shortens the course of diarrhea bc bacterial fermentation of starch in the colon results in short-chain fatty acid formation which stimulates Na absorption and decreases fluid loss

37
Q

Should abc be used to treat v. cholera?

A

No, only in severely dehydrated patients!

38
Q

Prevention of V. cholera?

A

Proper food handling and vaccine if traveling to endemic areas

39
Q

The O1 cholera vaccine has some cross-reactivity for _____, but does not protect against _______ .

A

ETEC; O139

Micro Exam 4 (8 decks)

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