Improved Differential Isolation of Yersinia Species Using a Modified Cefsulodin-Irgasan-Novobiocin Agar

Begin with cultures of Gram-negative Yersinia species and non-Yersinia Enterobacteriaceae.

Using sterile needle inoculators, dot the cultures onto both traditional Cefsulodin-Irgasan-Novobiocin or CIN agar and modified CIN agar.

Incubate the plates to promote bacterial growth.

Both traditional and modified CIN agars support the growth of Yersinia and non-Yersinia Enterobacteriaceae that ferment mannitol to produce acidic byproducts.

Acid production lowers the pH and triggers a color change, resulting in a characteristic red-centered colony morphology.

Modified CIN agar contains additional substrates that detect specific enzymatic activities expressed by non-Yersinia Enterobacteriaceae.

These bacteria metabolize the substrates, resulting in pH shifts or pigment production that alter the colonies' morphology.

In contrast, Yersinia species retain their characteristic red-centered appearance.

As a result, modified CIN agar enables differentiation between Yersinia species and non-Yersinia Enterobacteriaceae based on their distinct metabolic activities.