Do you know all the microbe types?
What is the etiologic agent of diphtheria?
Corynebacterium diphtheriae.
Describe the Gram stain characteristics of C. diphtheriae.
Gram-positive, pleomorphic, non-spore-forming rods.
What key virulence factor is responsible for the systemic effects of diphtheria?
The diphtheria toxin.
How is the diphtheria toxin produced?
It is produced by C. diphtheriae only after lysogenization by a bacteriophage carrying the tox gene.
What is the mechanism of action of the diphtheria toxin?
It inactivates elongation factor 2 (EF-2) via ADP-ribosylation, inhibiting protein synthesis.
What is the classic clinical presentation of respiratory diphtheria?
Sore throat with a grayish pseudomembrane over the tonsils and pharynx.
What physical sign is often noted in severe diphtheria cases?
“Bull neck” due to marked cervical lymphadenopathy and edema.
How is diphtheria primarily transmitted?
Via respiratory droplets from infected individuals.
Which culture medium is used for isolating C. diphtheriae?
Tellurite agar (e.g., cystine-tellurite blood agar).
What diagnostic test is used to confirm toxin production?
The Elek test.
How is diphtheria prevented?
Through immunization with the diphtheria toxoid (e.g., DTaP/Tdap vaccines).
What is the first-line treatment for diphtheria?
Administration of diphtheria antitoxin and antibiotics such as erythromycin or penicillin.
Why is early antitoxin administration critical?
Why is early antitoxin administration critical?
: What systemic complications can arise from diphtheria toxin?
Myocarditis and peripheral neuropathy.
What constitutes the pseudomembrane in diphtheria?
A mix of necrotic epithelial cells, fibrin, leukocytes, and bacteria.
Which age group is most at risk for diphtheria?
Primarily unvaccinated children, though all age groups can be affected if unvaccinated.
How does high vaccination coverage contribute to diphtheria control?
It provides herd immunity, reducing the spread and outbreak potential.
Describe the pathogenesis of diphtheria.
The bacteria colonize the upper respiratory tract, produce toxin, and cause local necrosis and systemic effects.
What distinguishes respiratory diphtheria from cutaneous diphtheria?
Respiratory diphtheria forms a pseudomembrane in the throat, while cutaneous diphtheria causes skin ulcers.
How can complications be minimized in diphtheria management?
Through early diagnosis, prompt antitoxin administration, and appropriate antibiotic therapy.
What distinguishes respiratory diphtheria from cutaneous diphtheria?
Respiratory diphtheria forms a pseudomembrane in the throat, while cutaneous diphtheria causes skin ulcers.