This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Which organism cannot be cultured in cell-free media 
Select and explain. 
A. Klebsiella rhinoscleromatis, B. Klebsiella ozaenae, C. Treponema pallidum, D. Sporothrix schenckii
C: Treponema pallidum
Answer: C: Treponema pallidum 
Explanation: Treponema cannot be grown in aificial culture media but is maintained by subculture in susceptible animals. Sporothrix is a dimorphic fungus, that form yeast in tissues at 37C and the mycelial phase in the culture at 25C. Klebsiella grows on ordinary media. Reference: Textbook of Microbiology; Ananthanarayan and paniker's; 10th edition; Pg: 379