CHROMagar™ Y. enterocolitica

For the Detection and Differentiation of Pathogenic Yersinia enterocolitica

CHROMagar™ Y. enterocolitica is a selective chromogenic culture medium developed for the isolation, differentiation, and presumptive identification of pathogenic Yersinia enterocolitica directly from clinical and environmental specimens. This medium allows clear color-based distinction between pathogenic strains (biotypes 1B, 2, 3, 4, 5), which appear mauve, and non-pathogenic strains (biotype 1A), which appear metallic blue. Most background flora is either inhibited or visually distinct, minimizing false positives and simplifying interpretation.

It is a powerful alternative to conventional media such as CIN agar, which lacks differentiation between pathogenic and non-pathogenic strains and often results in high false-positive rates due to similar colony appearances from other enteric bacteria.

Colony Appearance

Performance

Yersinia enterocolitica is a psychrotrophic, zoonotic foodborne pathogen capable of growing at refrigeration temperatures, making it a persistent food safety risk, especially in pork and processed meats. It is now recognized as one of the leading causes of acute bacterial gastroenteritis, particularly in children.

However, only certain biotypes of Y. enterocolitica are pathogenic. Traditional media such as CIN agar do not differentiate between these biotypes, leading to increased laboratory workload and potential misinterpretation.

CHROMagar™ Y. enterocolitica addresses these limitations by providing:

• Clear differentiation between pathogenic and non-pathogenic strains
• Suppression of interfering flora
• High specificity and interpretability

Intended Use

CHROMagar™ Y. enterocolitica is intended for:

• Qualitative detection, differentiation, and presumptive identification of pathogenic Y. enterocolitica from:
  • Clinical specimens (rectal swabs, stool samples)
  • Food samples (pork, processed meats, dairy)
  • Animal feed and environmental swabs

The test is conducted after direct plating or post-enrichment, with incubation for 36–48 hours at 30 °C ± 2 °C under aerobic conditions.

Not intended to diagnose infection or guide therapy. Suspect colonies should be confirmed via biochemical or molecular testing.

Advantages

1. High Specificity
   Pathogenic Y. enterocolitica colonies appear mauve, enabling differentiation from:
   • Non-pathogenic strains: metallic blue
   • Background flora: Inhibited or distinguishable
2. Reduced False Positives
   Unlike CIN agar, CHROMagar™ Y. enterocolitica eliminates misleading colony colorations from organisms like Citrobacter and Proteus.
3. Improved Detection Accuracy
   Allows laboratories to focus on clinically relevant strains, reducing workload and improving efficiency.
4. Enhanced Readability
   Color differentiation simplifies interpretation in high-volume or complex samples, such as stool or food matrices.

Test Procedure

1. Sample Type: Stool, rectal swabs, pork products, environmental swabs
2. Inoculation: Direct plating or after enrichment (e.g., cold enrichment or PSB broth)
3. Incubation:
   • Temperature: 30 °C ± 2 °C
   • Time: 36–48 hours
   • Atmosphere: Aerobic
4. Interpretation:
   • Mauve colonies = presumptive pathogenic Y. enterocolitica
   • Metallic blue colonies = likely non-pathogenic
   • Other colors = background flora or inhibited organisms

Ordering Information

Includes:

• Base medium YE492(B)
• Supplement YE492(S)

Storage & Shelf Life

• Storage: 2–8 °C, dry, sealed
• Shelf Life: Up to 24 months from manufacture
• Prepared Media: Use within validated expiry period as specified

Scientific Publications

• Nilsson et al., 2018 – Comparison of CHROMagar™ vs CIN agar for human pathogenic Y. enterocolitica
• Rasback et al., 2018 – Prevalence of pathogenic Y. enterocolitica in Swedish pig farms
• Renaud et al., 2013 – CHROMagar™ vs CIN for Yersinia in stool samples (J. Clin. Microbiol.)

CHROMagar™ Y. enterocolitica provides a clear, fast, and highly specific solution for the detection of pathogenic Yersinia enterocolitica in clinical, food, and environmental samples. With color-based biotype differentiation, suppressed background flora, and improved accuracy over CIN agar, it is an essential tool for laboratories performing food safety screening, zoonotic surveillance, and public health investigations.