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Which microorganism causes syphilis?
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sexually transmitted disease
Scanning electron micrograph of the spirochete Treponema pallidum attached to testicular cell membranes.
Syphilis is a systemic disease caused by the spirochete bacterium known as Treponema pallidum.1
This slender, coiled, and flexible microorganism requires moisture to survive and is most commonly transmitted through sexual intercourse. Once inside the body, T. pallidum reproduces in the tissues and remains present for the lifetime of the infected individual unless it is eliminated through medical treatment, such as with penicillin.1