Vibrio Cholera

Question 1

Vibrio cholera Characteristics

Answer 1

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

Question 2

Main risk factor of v. cholera

Answer 2

consumption of raw or improperly cooked oysters

Question 3

Vibrio cholera biofilms are supported by

Answer 3

RbmA, Bap1, RbmC

Question 4

What media should be used to culture v. cholera?

Answer 4

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

Question 5

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

Answer 5

O1, O139, O141, O75

Question 6

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

Answer 6

O1, O139

Question 7

New strain of v. cholera are due to

Answer 7

lateral transfer of gene cassettes responsible for O-antigen biosynthesis

Question 8

Newer strains of v. cholera are

Answer 8

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

Question 9

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

Answer 9

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

Question 10

Transmission of v. cholera is

Answer 10

BIMODAL

Question 11

Explain the bimodal transmission of v. cholera

Answer 11

• 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

Question 12

In epidemic situations, v. cholera is spread

Answer 12

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

Question 13

Risk factors for v. cholera?

Answer 13

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

Question 14

Reservoir for v. cholera?

Answer 14

zooplankton, humans

Question 15

V. cholera’s virulence factors

Answer 15

TCP, CT-1, CT-2, MARTX

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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)

Question 18

CT-1/2 bind

Answer 18

Gm1 ganglioside

Question 19

CT-1/2 activate

Answer 19

adenylate cyclase and cAMP

Question 20

CT-1/2 cause

Answer 20

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

Question 21

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

Answer 21

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)

Question 22

Host defense against v. cholera is primarily?

Answer 22

CD4 T-cell dependent & IgA

Question 23

V. cholera inhabits the

Answer 23

small intestines

Question 24

MARTX is related to

Answer 24

Clostridium difficile toxin B

Question 25

V. cholera - Incubation period:

Answer 25

1-5days

Question 26

Main Symptoms of v. cholera

Answer 26

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

Question 27

What would lab values for Extreme dehydration look like:

Answer 27

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

Question 28

Without treatment the chance that this patient may die is?

Answer 28

60%

Question 29

Disease usually resolves in

Answer 29

1-3, but may last up to 7days

Question 30

V. cholera is a toxemia meaning:

Answer 30

V. cholera adheres to the small intestine producing CT enterotoxin

Question 31

CT-1/2 are heat-labile meaning

Answer 31

they are killed by proper cooking

Question 32

Diagnostic fecal exam would reveal

Answer 32

GN curved rods w/ flagella

Question 33

Serotyping

Answer 33

is essential

Question 34

Treatment of v. cholera should include

Answer 34

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

Question 35

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

Answer 35

Zinc and amylase-resistant starch (decreased fluid loss)

Question 36

Mechanism for amylase-resistant starch

Answer 36

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

Question 37

Should abc be used to treat v. cholera?

Answer 37

No, only in severely dehydrated patients!

Question 38

Prevention of V. cholera?

Answer 38

Proper food handling and vaccine if traveling to endemic areas

Question 39

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

Answer 39

ETEC; O139