Habitat and Morphology of Corynebacterium diphtheriae

Habitat of Corynebacterium diphtheriae

1. Found in nasopharynx as well as in skin lesions, which actually represent a reservoir for the spread of diphtheria.
2. Also found in mouth, throat, nose, skin and wound of infected person.
3. Animals do not easily contract diphtheria.
4. Patients carry toxigenic organism upto 3 months after infection.

Morphology of Corynebacterium diphtheriae

1. They are gram +ve rod shaped bacteria.
2. Club shaped
3. Irregular swelling at one end or both end gives them the “Club Shaped” appearance.
4. Thin and slender, long, curved
5. Also known as Kleb’s-Loeffler Bacillus.
6. 3 µm to 5 µm x 0.5 µm to 0.8 µm in diameter
7. Non-capsulated
8. Non-sporing
9. Non-motile
10. Chinese letter arrangement, V or L shaped
11. Pleomorphic (Changes in shape and size of the bacteria)
12. Seen in pairs or in small groups, appears in clusters
13. Arranged in various angles to each other.
14. Forms granules (metachromatic granules)
15. Granules are the store house of energy
16. Lipid rich cell wall contains mesodiaminopimelic acid, arabino-galactam polymers and short chain mycolic acid.
17. Pili present
18. Alberts’s stain and Ponder’s stain shows metachromatic granules formed in the polar regions
19. Appears green in Alberts’s stain along with bluish black metachromatic granules at the poles.

Genome of Corynebacterium diphtheriae

1. Contains 2389 Genes
2. Protein encoding genes: 2272
3. Have 69 Structural RNA gene
4. Genome Length: 2,488,635 nucleotide
5. 87% are coding
6. G+C Content: 53%
7. No plasmid
8. Contains Pathogenicity Islands (PAI’s)

Habitat and Morphology of Corynebacterium diphtheriae