Spirochete

spirochete

Scanning electron micrograph of the spirochete Treponema pallidum attached to testicular …

(credit: ASM/Science Source)

Any of an order (Spirochaetales) of spiral-shaped bacteria. Some are serious pathogens for humans, causing such diseases as syphilis, yaws, and relapsing fever. Spirochetes are gram-negative (see gram stain) and motile. They are unique in that their flagella, which number between two and more than 200 per organism, are contained within the cell. Most spirochetes are found in a liquid environment (e.g., mud and water, blood and lymph). Several species are borne by lice and ticks, which transmit them to humans.

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spirochete [′spī·rə‚kēt]

(microbiology)

The common name for any member of the order Spirochaetales.

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Spirochete 

a bacterium, measuring 0.1–0.6 micrometer in diameter and 5–500 micrometers in length, in the form of an elongated coiled spiral. The majority of species have a slender axis filament around which the body of the cell is spirally coiled. Spirochetes lack flagella and are characterized by undulating movements, during which the cells rotate around their long axis. Reproduction is by transverse fission.

Spirochetes may be nonpathogenic or pathogenic. The former inhabit freshwaters, and the latter parasitize mollusks and cause syphilis in man (Treponema pallidum), relapsing fever (Borrelia recurrentis), and other spirochetoses. Under artificial conditions, nonpathogenic spirochetes grow on ordinary nutrient mediums and pathogenic spirochetes grow on mediums that contain serum and pieces of fresh tissue or the internal organs of animals. Some forms have not yet been grown in the laboratory.