The bacteria that cause syphilis infections are only able to survive moments outside of the body before they die.  For someone to pass on syphilis, another person must come into direct contact with a lesion ( painless sore or mucus patch) containing live bacteria on the infected person. The most common situation is during oral or penetrative sex where an individual has a sore on their genitas which comes into contact with another person thereby spreading the infection. It is not possible to indirectly pass on the infection through an inanimate object such as a door handles, toilet seats, eating utensils, hot tubs, swimming pools, shared clothing, bath tubs and other such objects.  However it is possible to pass syphilis through the sharing of sex toys that have been used by someone infected with syphilis.