Yersinia enterocolitica and Yersinia pseudotuberculosis Detection in Foods

Figure 3

Colonies of Y. enterocolitica grown on CIN agar and mVYE agar incubated at 30°C for 24 h. Yersinia colonies on CIN form the characteristic deep red center (“bull’s eye”) with a transparent margin and diameter 2–4 mm. Pathogenic Y. enterocolitica serotype O:3/biotype 3 variant VP^- (white arrow) forms red colonies and is easily differentiated from most nonpathogenic Yersinia organisms (black arrow) and other Gram-negative bacteria, which form dark-red colonies with a dark peripheral zone as a result of mannitol fermentation and esculin hydrolysis.