Characteristics Shape of Pathogenic Bacteria

Morphological characteristics of pathogenic bacteria help us to identify them when we stain microbiological specimens and view them under a microscope.

In this blog post, I am going to share some of the distinguishing characteristics shapes of pathogenic bacteria.

1. Vibrio cholerae: Comma “Curved” Shaped Gram-negative rod.
2. Campylobacter:  Curved Gram-negative rods that appear either a comma or S-shaped.
3. H. Influenzae: Small, Gram-negative coccobacilli.
4. Staphylococci: Spherical, gram-positive cocci arranged in irregular, grape-like clusters.

5. 

   Streptococci: Spherical, Gram-positive cocci arranged in chains or pairs.

6. Streptococcus pneumoniae (pneumococci): Gram-positive lancet-shaped cocci arranged in pairs (diplococci) or short chains.
7. Neisseria (N. gonorrhoeae and N. meningitidis): Gram-negative cocci that resemble paired kidney bean-shaped.
8. Bacillus anthracis: Large, Gram-positive rod with square ends, frequently found in chains.
9. Clostridium tetani: Gram-positive rod with characteristics “tennis racket shaped” or “Drum stick appearance” (because of terminal spore).
10. Clostridium perfringens: Large, Gram-positive, “boxcar” shaped rods.
11. Fusobacterium spp: These pleomorphic, long Gram-negative rods often with tapered “pointy” ends.

    

12. Corynebacteria: Gram-positive rods that appear club-shaped and are arranged in palisades or in V or L shaped formations (“Chinese-Letter” appearance).
13. Listeria monocytogenes: It is a small Gram-positive rod arranged in V or L shaped formations similar to corynebacteria.
14. Spirochetes (Treponema, Leptospira, and Borrelia): Thin-walled, flexible, spiral rods  (Corkscrew shaped) seen only by darkfield microscope and generally not seen in a standard light microscope.
15. Borrelia: They are corkscrew-shaped and are larger than the Treponema, they can be viewed under a light microscope with Giemsa or Wright stains.