Bacterial Shapes and Examples: Curved and Spiral

Bacterial Shapes

• Curved bacteria, also known as Sprilla, are typically comma-shaped and usually occur singly, but some species can form pairs, resembling a bird with a "gull wing" morphology.
• Examples of curved bacteria include Vibrio spp, such as V. cholera, which causes cholera, and V. parahaemolyticus, which causes diarrhea.

Spiral-shaped Bacteria (Spirochetes)

• Spiral-shaped bacteria, known as spirochetes, are characterized by their spiral or helical shape, flexibility, and axial filament, which aids in motility.
• The axial filament is a key feature that distinguishes spirochetes from other bacteria, and it helps in the twisting motion of the bacterium's motility.
• Different species of spirochetes vary in size, length, rigidity, and the number and amplitude of their coils.

Specific Examples of Spirochetes

• Treponema pallidum is a tightly coiled spirochete that causes syphilis, a sexually transmitted infection, and has a flexible cell wall that enables it to move readily through tissues.
• Borrelia spp. are less tightly coiled spirochetes that cause Lyme disease and relapsing fever.

Pleomorphic Bacteria

• Pleomorphic bacteria are those that can exist in a variety of shapes, a phenomenon known as pleomorphism.
• Some bacteria may lose their characteristic shape due to adverse growth conditions.

Cell Wall-less Bacteria

• Bacteria in the genus Mycoplasma lack cell walls.