Which characteristic can differentiate Yersinia enterocolitica from Yersinia pestis?

Which characteristic can differentiate Yersinia enterocolitica from Yersinia pestis?

• A. Motility at 25C
• B. Motility at 37C
• C. Glucose fermentation
• D. H2S production

Answer: (A)

Temperature-dependent motility is what sets these two apart. Yersinia enterocolitica is motile at room temperature (around 25°C) because it has flagella expressed at that lower temperature, so you can observe movement in a motility test or on a semi-solid medium. At body temperature (37°C) it loses this motility due to down-regulation or absence of flagella. Yersinia pestis, on the other hand, is nonmotile and lacks flagella across temperatures, so it does not move in motility tests at either temperature. Because of this, motility at 25°C distinguishes Y. enterocolitica from Y. pestis. The other options don’t provide separation since both species ferment glucose and neither typically produces H2S, and motility at 37°C is not a reliable differentiator since both can be nonmotile at that temperature.

Temperature-dependent motility is what sets these two apart. Yersinia enterocolitica is motile at room temperature (around 25°C) because it has flagella expressed at that lower temperature, so you can observe movement in a motility test or on a semi-solid medium. At body temperature (37°C) it loses this motility due to down-regulation or absence of flagella. Yersinia pestis, on the other hand, is nonmotile and lacks flagella across temperatures, so it does not move in motility tests at either temperature. Because of this, motility at 25°C distinguishes Y. enterocolitica from Y. pestis. The other options don’t provide separation since both species ferment glucose and neither typically produces H2S, and motility at 37°C is not a reliable differentiator since both can be nonmotile at that temperature.