This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology (Haemophilus, Yersinia, Spirochaetes, Ricketssia, Chlamydia, Mycoplasma and Miscellaneous Bacteria), Subject name: Microbiology
In a syphilis patient, site which does not help in isolation of organism:- 
Select and explain. 
A. Gumma, B. Primary chancre, C. Mucosal patch, D. Maculopapular rash
A: Gumma
Answer: A: Gumma 
Explanation: 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.