Spiral bacteria

Spiral bacteria, bacteria of spiral (helical) shape, form the third major morphological category of prokaryotes along with the rod-shaped bacilli and round cocci. Spiral bacteria can be subclassified by the number of twists per cell, cell thickness, cell flexibility, and motility.

A spirillum (plural spirilla) is a rigid spiral bacterium that is Gram-negative and frequently amphitrichous or lophotrichous. Examples include:

A spirochete (plural spirochetes) is a very thin, elongate, flexible, spiral bacteria that is motile via endoflagella. Owing to their morphological properties, spirochetes are difficult to Gram-stain but may be visualized using dark field microscopy or Warthin–Starry stain. Examples include:

A vibrio (plural vibrios) is a member of the genus Vibrio, containing Gram-negative, comma-shaped rods with a partial twist. Examples include:

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