<prompt> In a syphilis patient, site which does not help in isolation of organism:-GummaPrimary chancreMucosal patchMaculopapular rash  <response>: T. pallidum is very difficult to demonstrate in Gumma Teiary syphilis. Infectivity of a patient to the sexual paner is maximum during primary, secondary and early latent stage. During these stages spirochetes are abundant in the lesions. 