Which statement about Treponema pallidum culture is true?

Which statement about Treponema pallidum culture is true?

• A. It can be cultured easily in standard bacterial media.
• B. It can be cultured in cell culture with no special conditions.
• C. It cannot be cultured in vitro and must be cultured in rabbits.
• D. It grows in plants.

Answer: (C)

Treponema pallidum is extremely fastidious and cannot be grown in standard artificial media. It has historically required a living host to propagate, with rabbit testes being the classic in vivo system used to maintain and study the organism. Because it does not grow reliably in vitro on ordinary media or simple cell cultures, the statement that it cannot be cultured in vitro and must be cultured in rabbits is the true one. It also explains why options suggesting easy growth in standard media, basic cell culture, or plant hosts are incorrect. In clinical practice, culture is not relied upon; diagnosis is made by serology, dark-field microscopy, or molecular methods.

Treponema pallidum is extremely fastidious and cannot be grown in standard artificial media. It has historically required a living host to propagate, with rabbit testes being the classic in vivo system used to maintain and study the organism. Because it does not grow reliably in vitro on ordinary media or simple cell cultures, the statement that it cannot be cultured in vitro and must be cultured in rabbits is the true one. It also explains why options suggesting easy growth in standard media, basic cell culture, or plant hosts are incorrect. In clinical practice, culture is not relied upon; diagnosis is made by serology, dark-field microscopy, or molecular methods.