Description
Yersinia enterocolitica is recognised as a water and food-borne human pathogen. It is a cause of diarrhoeal disease in man. It has been shown to cause diarrhoea, fever, nausea, polyarthritis, meningitis, peritonitis, cholecystitis, septicaemia, and abscesses of the spleen and colon. With modern techniques it is being realised that Yersinia enterocolitica is more widespread than previously suspected.
Yersinia Selective Agar Base AM226, and Supplement SP478, based on the work described by Schiemann in 1979 and incorporating his later modifications, is specifically designed to isolate and cultivate, Yersinia enterocolitica at 18 to 24 hours. Typical colonies develop a dark red centre, surrounded by a transparent border, which can be smooth or irregular, but vary among serotypes in colony size and ratio of the centre to border. At 48 hours, the colonies appear dark pink with the translucent border and are often surrounded by a zone of precipitated bile. The presence of Desoxycholate, Irgasan and Crystal Violet, markedly inhibit the growth of Gram Positive and some Gram Negative organisms.
Cefsulodin and Novobiocin improve the inhibition of normal enteric organisms. The differential characteristics of the media rely on the fermentation of Mannitol. This fermentation produces a pH drop at the colony, which by the absorption of Neutral Red imparts the red centre. Colonies that do not utilise Mannitol, remain colourless and translucent.
