Question

Question 4 (1 point) Saved 4. Which of the following does NOT produce an exotoxin as a virulence factor? a) Salmonella Ob) Shigella O c) E. coli O157:H7 O d) Campylobacter

Answer 1

Answer- Salmonella

Explanation- Shigella flexneri which is a member of genus Shigella produces shiga toxin which causes destruction of villi and mucus of colon there by causes the disease named as shigellogis. This shiga toxin is ultimate virulenece factor that causes the disease.

So, option B is incorrect.

E.coli 0157:H7 produces an exotoxin like shigatoxin. That's why this strain of E.coli is also known as STEC. This bacteria causes diarrhoea with often release of blood.

So, option C is incorrect.

Campylobacter causes diarrhoeal disease where the exotoxin cytolethal distending toxin plays an important role. Campylobacter infection can occurs due to eating raw eggs.

So, option D is incorrect.

Members of genus Salmonella are gram negative. As in gram negative bacteria, on outer membrane there is lipopolysaccharide layer. Salmonella possess a endotoxin which act as virulenece factor. This endotoxin causes the rupture of epithelial cells and cause disease.

So, option A is correct answer.