12 - Vibrio species Flashcards
Give me the characteristics of Vibrio sp.
- Gram -
- nonspore-forming
- vibrio shaped bacterium
Within the Vibrio genus there are ____ species, at least ___ species that are causative agents in human infection
96
12
Most illness is caused by just 3 Vibrio species:
- Vibrio parahaemolyticus
- Vibrio vulnificus
- Vibrio cholera (more waterborne than foodborne infection)
Vibrio sp. is a predominant bacterial genus in ___________
estuarine waters
T or F: most Vibrio isolates, in each of the potentially pathogenic species, are non-pathogenic
T
T or F: A few strains in each of these species (V.cholerae, V.parahaemolyticus, and V.vulnificus) have picked up virulence factors which cause illness in humans
T
Vibrio infection is generally associated with _________ consumption or _______ contact
seafood
The number of vibrios in the water vary by ____________ so there are definite spikes in the summer months
water temperature
T or F: vibrios are more common in warmer waters
T
With the exception of V. cholerae ___ or______, vibrios in water are part of the natural microbiota of the water and not caused by fecal contamination
the fecal oral route does not apply to Vibrio
O1 or O139
Vibrio parahaemolyticus symptoms include:
- diarrhea
- abdominal cramping
- fever
- headache
- nausea
- vomiting
Vibrio parahaemolyticus is the most common vibrio infection from Canadian seafood, when the water that oysters are harvested from goes above ___C it’s Vibrio season
17
T or F: Colder waters produce safer seafood (if only considering Vibrio infections)
T
V.parahaemolyticus is serotyped according to it’s ____ antigen and _______________ antigen
LPS (O)
capsular polysaccharide (K)
*Canadian West Coasr its O4:K12
V.parahaemolyticus infections are almost exclusively linked to ______________
the consumption of raw or undercooked seafood
A key feature is that V.parahaemolyticus has a generation time of ___ to ___ minutes at ____ C, the ability to grow rapidly means that contaminated food becomes highly colonized if temperature abused
8-9 mins
37C
V.parahaemolyticus symptoms subside in ________ days
3-5
Symptoms of V.parahaemolyticus appear __ to ___ hours after ingestion of contaminated food
4-30
V.parahaemolyticus has a ___________ at one pole of the bacterium for swimming motility
single flagellum
For V.parahaemolyticus, during growth in ________________, flagella are produced along the lateral side of the bacterium, which aid in swarming motility
semi-solid media
______ is a multivalent adhesion protein that binds to fibronectin and phosphatidic acid, which is required for the initial attachment to host cells
MAM7
V.parahaemolyticus can utilize the __________, ___________, and _____________, along with ______, to scavenge iron from the environment
- siderophores vibrioferrin
- ferrichrome
- aerobactin
- heme
Why does V.parahaemolyticus causes haemolysis?
because it scavenges iron
The iron transporters of V.parahaemolyticus are internalized by different ________________ on the outer membrane of the bacteria and transported to the cytoplasm by different ________________
membrane receptors
ABC complexes
What are the 3 virulence factors of V.parahaemolyticus and what do they cause:
- Toxins: hemolysis and cytotoxicity
- T3SS1 effectors: cytotoxicity
- T3SS2 effectors: enterotoxicity and cytotoxicity
_________ is the most serious vibrio infection, responsible for 95% if seafood related deaths in North America
Vibrio vulnificus
Vibrio vulnificus are not serotyped but they are divided into 3 biotypes based on biochemistry:
Biotype 1: causes disease in humans
Biotype 2: causes disease in eels, and rarely in humans
Biotype 3: is a hybrid of biotype 1 and 2 and is found only in Israel
There are 2 distinct V. vulnificus syndromes:
1) Primary septicemia caused by consuming raw or undercooked seafood
2) Necrotizing wound infection which results from an open wound being exposed to warm seawater, or contaminated seafood, with high concentration of V. vulnificus
V. vulnificus primary septicemia cases resulting from raw oyster consumption have fatality rates of ____
60%
wound infections from handling contaminated seafood with cuts or scratches have ____ fatality rates, surgery may be required to clean the infected tissue and some cases require amputation
20-25%
Vibrio vulnificus is only isolated from ______ water
warm
Symptoms of vibrio vulnificus can appear __ hours to several days after exposure, symptoms include :
7
fever, chills, nausea and hypotension
Virulence factors for V. vulnificus are poorly understood but are known to include:
- The polysaccharide capsule (K-antigen), if cells lose the K-antigen they lose virulence
- LPS (O-antigen), the high fever, systemic infection, and shock are consistent with LPS induced endotoxic shock
- vvhA: a heat-stable haemolysin/cytotoxin that is unique to V. vulnificus and likely plays a role in virulence
At the moment, V.cholerae is endemic in ______ because of ongoing conflicts destroying:
Yemin
health, water and sanitation infrastructure and malnutrition have caused the people to be more vulnerable to diseases
Serotyping of V.cholerae is based only on the ______ antigen
LPS (O)
V. cholerae ____ and _____ are one of the few foodborne illness which is known to cause _____ and _______
O1 and O139
epidemics and pandemics
*during epidemics fecal contamination of the water is a source of other illnesses
V. cholerae O1 and O139 produce ________
cholerae toxin (ctx)
Is V. cholerae an issue in Canadian seafood and why?
this is generally not an issue in canadian seafood because our waters are too cold, occasionally we can see it in travellers returning from abroad
V. cholerae has _____ state where cells are reduced in size and become ovoid
VBNC
VBNC cells are not culturable on any media, hoewever when injected into rabbits they cause _____________________
ileal loop fluid accumulation
Patients who recover from infection without antibiotics excrete V. cholerae for ________ weeks in their feces
1-2
V. cholerae colonizes the small intestine using __________
adherence factors
The CTX toxin produced by V. cholerae disrupts:
the ion transport which leads to severe diarrhea
The CTX toxin is carried on a _____, only V. cholerae which are infected with this ____ are able to cause illness in humans
phage
T or F: Vibrio has highly fluid and plastic genomes
T
V. parahaemolyticus carries the genes for its K and O antigens in 2 discrete clusters, which can rapidly undergo ________________
horizontal gene transfer
*therefore V. parahaemolyticus has been known to switch serotypes mid-outbreak
T or F: V. cholerae becomes naturally competent when it is grown on chitin (i.e. crustacean shells) and readily takes up DNA from the environment
T
T or F: V. cholerae needs to be infected with a phage to be virulent
T
*climate change occurs the probability that this will happen
T or F: The T3SS sometimes gets transferred from V. parhaemolyticus to V. cholerae however, when this happens it makes V. cholerae pathogenic to humans, although, the symptoms of illnesses caused by these strains are more inline with a V. parahaemolyticus infection than with a V. cholerae infection
T
V. parahaemolyticus wihtout the genes for _______ do not cause illness (probably)
tdh/trh
How can you prevent Vibrio infection?
- Vibrios are sensitive to cold so seafood should always be frozen, refrigerated, or stored on ice and should be eaten fresh
- cooking is very effective at eliminating vibrios
- irradiation and high hydrostatic pressure kills pathogenic vibrios
- dried spices, herbal oils, tomato sauce and organic acids (lemon juice)
T or F: depuration removes Vibrio
F
T or F: Although these three species cause illness, most isolates from each species are non-pathogenic, though some have acquired virulence factors through gene horizontal transfer
T
V.parahaemolyticus produces 3 haemolytic toxins:
1) a thermoliable haemolysin (tlh)
2) a thermostable direct haemolysin (tdh)
3) a thermostable direct-related haemolysin
The TDH and TRH toxins of V.parahaemolyticus are secreted by the bacteria and form _________________ in the host membrane
tetrameric pore complexes
The tetrameric pores formed by TDH/TRH, allow ________ to flow freely across the host membrane which leads to haemolysis or cytotoxicity
ions
V.parahaemolyticus translocates T3SS1 effectors into host cells to cause cytotoxicity in different cell types such as __________ and _________
macrophages
Hela cells
T or F: T3SS1 is found in all V.parahaemolyticus isolates even non-pathogenic isolates, indicating an important role in environment
T
T3SS2 effectors are translocated into host cells to cause ___________ of colon epithelial cells or __________
cytotoxicity
enterotoxicity
_________ is found mainly in clinical isolates, indicating that it is more tightly tied to pathogenic lifestyle
T3SS2
Explain how the ctx produced by V.cholerae leads to acute diarrhea:
1) V.cholerae releases cholera toxin (ctx) that binds to ganglioside receptors on the surface of intestinal epithelium cells
2) ctx is internalized by endocytosis and triggers the production of cAMP (a 2nd messenger) within the cell
3) cAMP activates specific ion channels within the cell membrane, causing an efflux of ions from the cell
4) The build up of ions in the intestinal lumen draws water from the cells and tissues via osmosis causing acute diarrhea
5) As water is being removed from body tissues, dehydration will result if left untreated (this can be fatal)
