Characteristics of Treponema Pallidum, the Bacterium Which Causes Syphilis, Include

Characteristics of Treponema pallidum, the bacterium which causes syphilis, include all except

A) Gram- negative spirochete.
B) rapid invasion of host tissues from the initial infection site.
C) ability to avoid immune detection by varying the few antigens it carries on its surface.
D) not treatable with any of type antibiotic.
E) vertical transmission to a fetus during any stage of pregnancy.