Vibrio Cholera Flashcards
Vibrio cholera Characteristics
GN curved rod, facultative anaerobe, extracellular, non-invasive, oxidase +, Halophilic, motile - flagella
Main risk factor of v. cholera
consumption of raw or improperly cooked oysters
Vibrio cholera biofilms are supported by
RbmA, Bap1, RbmC
What media should be used to culture v. cholera?
TCBS agar (Thiosulfate-citrate-bile salts-sucrose agar)
6 different O antigen types of v. cholera, the most prevalent types in the US are?
O1, O139, O141, O75
6 different O antigen types of v. cholera, the most types that cause epidemics are?
O1, O139
New strain of v. cholera are due to
lateral transfer of gene cassettes responsible for O-antigen biosynthesis
Newer strains of v. cholera are
more virulent bc they have a greater ability to produce cholera toxin
new strain of v. cholera resistant to 3rd generation Abx was found, it contains
2 super bug genes (Metallo beta-lactamase-1 and plasmid-mediated beta-lactamase-1)
Transmission of v. cholera is
BIMODAL
Explain the bimodal transmission of v. cholera
- 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
In epidemic situations, v. cholera is spread
person-to-person (w/in 5hrs) at low infectious doses
Risk factors for v. cholera?
Warm, raw shellfish, contaminated food/water (salt-water) - esp if consumed w/ bicarb
Reservoir for v. cholera?
zooplankton, humans
V. cholera’s virulence factors
TCP, CT-1, CT-2, MARTX
Mechanism of Toxin Co-regulated Common Pili (TCP):
ESSENTIAL for colonization, attachment site for CTX phage (a lysogenic phage that contains genes encoding the cholera toxin)
Cholera Toxins-1/2 (CT-1 & CT-2) mechanism
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)
CT-1/2 bind
Gm1 ganglioside
CT-1/2 activate
adenylate cyclase and cAMP
CT-1/2 cause
secretion of Cl-, HCO3-, H2O = Watery diarrhea
Multifunctional-Autoprocessing Repeats-in-ToXins (MARTX) Mechanism
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)
Host defense against v. cholera is primarily?
CD4 T-cell dependent & IgA
V. cholera inhabits the
small intestines
MARTX is related to
Clostridium difficile toxin B
V. cholera - Incubation period:
1-5days
Main Symptoms of v. cholera
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
What would lab values for Extreme dehydration look like:
Hypovolemic shock, hemoconcentration, K depletion, loss of bicarb, severe acidosis
Without treatment the chance that this patient may die is?
60%
Disease usually resolves in
1-3, but may last up to 7days
V. cholera is a toxemia meaning:
V. cholera adheres to the small intestine producing CT enterotoxin
CT-1/2 are heat-labile meaning
they are killed by proper cooking
Diagnostic fecal exam would reveal
GN curved rods w/ flagella
Serotyping
is essential
Treatment of v. cholera should include
enteric isolation, administration of electrolytes and fluids (IV and oral)
What treatments may shorten the duration/severity of v. cholera?
Zinc and amylase-resistant starch (decreased fluid loss)
Mechanism for amylase-resistant starch
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
Should abc be used to treat v. cholera?
No, only in severely dehydrated patients!
Prevention of V. cholera?
Proper food handling and vaccine if traveling to endemic areas
The O1 cholera vaccine has some cross-reactivity for _____, but does not protect against _______ .
ETEC; O139
