Vibrio and Campylobacter Flashcards
How vibrio Cholera is serotyped?
We can serotype vibrio cholera on the basis of the O antigen
From where originates the disease cholera?
How it has spread?
It originates from India.
Because of traveling, it has spread.
Are they motile? Are they spore forming?
They are motile with a single polar flagellum
They are nonspore forming
What are the results of the oxidase and catalase tests?
They are oxidase positive, catalase positive
How vibrio cholera are transmitted?
- fecal oral route
- direct contact
- by ingestion: if ingestion of contaminated water, large infectious dose is needed / if ingestion of contaminated food, small infectious dose is needed
What is the clinical presentation?
Cholera: Rice water diarrhea and dehydration
In which case is the infectious dose is small? Large?
The infectious dose is large if with water, it is smaller if with food.
It is a small if the patient is achlorhydric (Low HCL in the stomach lumen) or taking antacids
Are bacteria sensitive to stomach acidity?
The small inoculum size needed when patients are achlorhydric or taking antacids explain the fact that these bacteria are very sensitive to stomach acidity
What’s the incubation period?
1 to 4 days
What is the site of infection?
Small intestine
To which cells bacteria adhere?
There is adherence to M cell in the ileum.
Which toxin is produced? By what it is encoded?
Cholera toxin which is an AB5 toxin
It’s encoded by chromosomal genes
To which receptors the toxic binds?
What is its structure?
It binds to ganglioside receptors.
It has 2 A subunits and 5 B subunits, helping in its stability as it adheres.
What is the function of this toxin?
A1 activates adenylate cyclase activity, increasing cAMP, leading to the secretion of more Cl-, and less absorption of Na+, and thus to osmotic loss of water to the lumen, which causes distention of the abdomen.
What are the symptoms of an infection?
- Nausea more than vomiting
- Diarrhea that starts slowly, then 20 to 30 L of electrolytes and fluids per day, causing dehydration, acidosis, and shock. The stool is rice water stool. It contains WBC, too many vibrios, and too much mucus.
What is the cause of suck in the case of Vibrios?
it is due to the endotoxin
What causes the diarrhea? Is there any bacteremia or invasion of bacteria?
It is just the toxin that causes the diarrhea, there is no invasion nor bacteremia
Which prophylactic measures should be taken before an epidemic?
- Antibiotics: tetracycline, but we cannot give it for a long time because of its side effects plus the plasmid mediated resistance
- Proper nutrition
What are the vaccines?
Vaccine from O antigen, Lipopolysaccharide extract
Vaccine of killed bacteria where all antigens are present without the DNA
When vaccines are given?
Vaccines are given before an epidemic, they are not efficient during an epidemic
What type of protection do they give? What is the validity of the vaccine?
They give you short term protection
The validity of the vaccine is for only 6 months, after which they have to receive it again
What specimen should be taken?
Specimen is taken from rice water stool
Are they gram negative or positive?
They are gram negative bacteria
What is their shape?
They are comma shaped with a single polar flagellum
