Spirochaete – Any non-rigid corkscrew-shaped bacterium.

Spirochaete move by means of flexions of the cell, produced by a series of rotary axial fibrils underlying the cell’s outer sheath.

Most spirochaetes are Gram-negative, anaerobic and feed on dead organic matter. They are particularly common in sewage-polluted waters.

Spirochaetes can cause disease in humans and animals. Treponema is the agent of syphilis.