Differentiating Yersinia species: Which laboratory findings can distinguish Yersinia enterocolitica from Yersinia pestis?

Introduction / Context:
Yersinia is a genus within Enterobacteriaceae that includes Y. pestis (plague) and Y. enterocolitica (enteric pathogen). Accurate differentiation relies on biochemical and phenotypic traits because therapy, transmission, and biosafety implications differ significantly between these species.

Given Data / Assumptions:

• Comparative traits include ornithine decarboxylation, sugar fermentation, and motility at lower temperatures.
• Testing is performed under standard laboratory conditions and quality controls.
• Cold enrichment and temperature-dependent motility are recognized features of Y. enterocolitica.

Concept / Approach:
Y. enterocolitica typically shows positive ornithine decarboxylase activity, variable but often positive fermentation of certain sugars (e.g., sucrose, cellobiose), and motility at room temperature (around 22–25°C) with a characteristic umbrella pattern in motility media; it becomes non-motile at 37°C. Y. pestis lacks these traits: it is ornithine decarboxylase negative, non-motile at 22°C and 37°C, and differs in sugar utilization profiles. Combining these tests delivers high discriminatory power.

Step-by-Step Solution:
Perform ornithine decarboxylase: positive suggests Y. enterocolitica. Assess sugar fermentation (sucrose, cellobiose): supportive for enterocolitica. Check motility at 22°C: motility favors enterocolitica; absence supports pestis. Integrate results to differentiate the two species confidently.

Verification / Alternative check:
Temperature-dependent motility and decarboxylase panels in commercial identification systems (e.g., API, VITEK) corroborate species-level calls when combined with clinical context.

Why Other Options Are Wrong:

• Single tests alone are helpful but strongest discrimination comes from a panel.
• None of these: Incorrect; all listed traits are used in practice.

Common Pitfalls:
Relying only on growth at 37°C (both grow) or overlooking temperature effects on motility; misreading weak decarboxylase reactions can also mislead.

Final Answer:
All of these.