Vibrio cholerae

Question 1

Disease of Vibrio cholerae

Answer 1

Cholera

Question 2

Characteristics of Vibrio cholerae

Answer 2

1_ Comma-shaped
2_ gram-negative rods.
3_ Oxidase-positive , which distinguishes them from Enterobacteriaceae.

Question 3

Habitat of Vibrio cholerae

Answer 3

1_ human colon

2_ shellfish.

Question 4

Transmission of Vibrio cholerae

Answer 4

fecal–oral route

Question 5

Pathogenesis of Vibrio cholerae

Answer 5

1Massive, watery diarrhea caused by enterotoxin that activates adenylate cyclase by adding ADP-ribose to the stimulatory G protein.
2 Increase in cyclic AMP causes outflow of chloride ions and water.
3_ Toxin has two components: subunit A, which has the ADP-ribosylating activity; and subunit B, which binds the toxin to cell surface receptors.
4_ Organism produces mucinase, which enhances attachment to the intestinal mucosa.
5_ Role of endotoxin is unclear.
6_ Infectious dose is high (>107 organisms). Carrier state rare.

Question 6

Symptom of Vibrio cholerae

Answer 6

Massive, watery diarrhea caused by enterotoxin.

Question 7

Why occur Massive, watery diarrhea in Cholera patient ?

Answer 7

Massive, watery diarrhea caused by (( enterotoxin )) that activates adenylate cyclase by adding ADP-ribose to the stimulatory G protein. Increase in cyclic AMP causes outflow of chloride ions and water.

Question 8

components of toxin in Vibrio cholerae

Answer 8

Toxin has two components:
subunit A : which has the ADP-ribosylating activity
subunit B: which binds the toxin to cell surface receptors.

Question 9

Laboratory Diagnosis

Answer 9

1Gram-stained smear and culture. (During epidemics, cultures not necessary.)
2 Agglutination of the isolate with known antisera confirms the identification.

Question 10

Treatment of Vibrio cholerae

Answer 10

1—Treatment of choice is fluid and electrolyte replacement.
2_ Tetracycline is not necessary but shortens duration and reduces carriage.

Question 11

Prevention of Vibrio cholerae

Answer 11

1_ Public health measures (e.g., sewage disposal, chlorination of the water supply, stool cultures for food handlers, and handwashing prior to food handling).
2_ Vaccine containing killed cells has limited effectiveness.
3_Tetracycline used for close contacts.

Question 12

Vaccine of Vibrio cholerae

Answer 12

Vaccine containing killed cells has limited effectiveness.