C.diphtheriae

Question 1

pathogenesis

Answer 1

Transmisson is by close contact with droplets from human carriers. Disease is due to production of the diphtheriae toxin encoded by the tox gene ,which is intergrated inside the bacterial chromosome on a lysogenic phage. clinical disease proceeds in two stages:local infection ,toxin production and toximea.

Question 2

local infection

Answer 2

primary infection occurs in the upper respiratory tracts.skin lesions and wounds can be infected. cutsneous diphteria is a secondary infection manifesting as deep ulcers that are slow to heal. The pathogens enters the body through this portal,reproduce and produce a toxin resulting in local cell damage. The inflammatory reaction leads to collection of a greyish -white exudate,the matrix of diphtherial pseudomembrane consinsting of fibrin,dead granulocytes and necrotic epithelial cells.

Question 3

toximea

Answer 3

systemic complication that occurs when the toxin is absorbed from the throat.The toxin travels to the heart and nerves by blood.It causes myocarditis in the heart and muscle paralysis when it affects the nerves.

Question 4

toximea is treated by

Answer 4

diphtheria antitoxin derived from horses.