C. Diptheriae Flashcards
Gram stain?
Positive
Aerobic or anaerobic?
Aerobic
Shape and motility?
Rod-shaped, non-motile.
Microscopically, what do they look like?
Chinese letters (irregular, club shape)
What is required for virulence?
Diptheria toxin. Dt coded by tox gene on lysogenic beta-prophage (lysogenic conversion).
What model of virulence does it follow?
A+B
What does A do?
Once endocytosed, it ADP-ribosylates EF-2 and halts protein synthesis.
What does B do?
Binds to heparin-binding EGF
How many molecules of diptheria toxin are required to kill one cell?
One
What happens when A+B colonizes in pharynx?
Forms pseudomembrane
What happens when A gets in the blood?
Organ damage: heart and cranial nerves
What is the presentation?
Sore throat with pseudomembrane on tonsils, throat, pharynx. Neck swelling. Skin lesions.
Diagnosis?
REQUIRED culture. Any confirmation of Dt.
Treatment?
Antitoxin for symptomatic cases. Abx for asymptomatic.
Does antitoxin neutralize bound toxin?
No
