CORYNEBACTERIUM.by Dr munir KGMC peshawarpesha

Corynebacterium

1. CORYNEBACTERIUM

2. Disease:
C. diphtheriae ( Loeffler’s bacillus)
causes diphtheria.
Membranous conjunctivitis
The bacterium causing diphtheria was
described for the first time by Kleb
(1883) and Loeffler in 1884
demonstrated its etiological significance

3. Important Properties:
Gram-positive rods that appear club-
shaped and arranged in V-or L-shaped
formations.
Produces large volutin (polyphosphate)
granules.
Normal flora of the skin and
nasopharynx

5. Metachromatic (Volutin) granules on Methyline blue
stain

6. Transmission:
Direct contact
Droplet nuclei
Pathogenesis:
Organism secretes an exotoxin that
inhibits eukaryotic protein synthesis.
Toxin has two components:
1.Subunit A, which causes membrane
formation by inhibiting protein synthesis
2.Subunit B, which binds the toxin to cell
surface receptors.

7. Pseudomembraneis produced by death
of mucosal/epithelial cells.
Clinical findings:
1.Diphtheria begins as mild pharyngitis
with slight fever and chills.
Spreads to the nasopharynxor to larynx
and trachea.
The diphtheria exotoxincirculates and
causes pathogenesis.

8. Spread results in a firmly adherent,
dirty gray, pseudomembrane.
This pseudomembrane may cause
asphyxiation.
Cervical adenitis and edema which, in
severe cases, may produce the
characteristic bull neck appearance.

11. Complications from systemic
circulation of diphtheria toxin:
Myocarditisand, occasionally, more
severe cardiotoxicity.
Paralysis of the soft palate and more
severe neuropathies.
2.Membranous conjunctivitis:
A rare disease.
It produces a severe inflammation of
the conjunctiva, associated with

12. formation of a membrane usually
on the palpebral conjunctiva.
The disease usually affects children
between 2-8 years of age who are not
immunized against diphtheria.
The child is toxic and febrile.
Scanty conjunctival discharge and
severe pain in the eye.

13. Lids are swollen and hard.
Conjunctiva is red, swollen and covered
with a thick grey-yellow membrane.
The membrane is tough and firmly
attached to the conjunctiva.
Later on pain decreases and the lids
become soft.
The membrane is sloughed off leaving a
raw surface.

14. Healing occurs by scar formation
Corneal ulceration is a frequent
complication in acute stage.
Late stage complications due to scarring
include symblepharon, trichiasis,
entropion and conjunctival xerosis.

17. Laboratory diagnosis:
It involves both isolating the organism
and demonstrating toxin production.
A.Organism isolation done by culture.
A throat swab is cultured on
a.Löffler'smedium.
On this medium, C.diphtheriae
produces polyphosphate granules
(volutin) that stain blue/red.

18. b.Tellurite plate.
c.Blood agar plate.
B. Toxin production confirmed by
different tests (Precipitin test)