Why is Treponema pallidum considered highly invasive in the body?

Treponema pallidum is considered highly invasive because it is one of the rare biotic agents capable of penetrating intact skin and mucosal linings of the body.1

While many bacteria are limited to surface infections or rely on specific enzymes to break down tissue integrity, T. pallidum possesses a high degree of invasiveness that allows it to spread throughout the body's tissues. Once it has entered the host, the spirochete can persist for the lifetime of the infected person if left untreated. In later stages of the disease, the organism can disseminate widely, attacking various organs, including the aorta and the central nervous system, leading to severe complications such as aneurysm, neurosyphilis, and paresis.123