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Isolation and identification of Yersinia pseudotuberculosis and Yersinia enterocolitica from cow raw milk in Tehran

Journal of Dairy, Veterinary & Animal Research
Mohammad Mehdi Soltan Dallal,1,2 Milad Abdi,3,4 Ramin Mazaheri Nezhad Fard,1,5 Behzad Mobasseri2

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Aims  and  background:Yersinia is a cocobacilliary gram-negative bacteria which can cause yersiniosis in all age groups. This study was carried out to investigate the presence of Yersinia pseudotuberculosis and Yersinia enterocolitica in raw milk of livestock farms in Tehran.

Materials and methods: Three hundred and sixty raw milk samples were collected from livestock  farms  in  Tehran  during  6  months.  Y.  pseudotuberculosis  and  Y.  enterocolitica  were isolated and identified according to the FDA guidelines. After treatment with low temperature (10°C for 10 days) and alkaline treatment (using KOH), the samples were cultured in the selective medium named CIN agar at 25°C. After incubation, colonies similar to the bull eye were chosen and characterized using phenotypic tests and ultimately confirmed by the API-20E strip test (Biomerieux, France) and detection of ail and inv genes by PCR. Serotyping and bio typing tests carried out on Y. enterocolitica isolates.

Results:  Of  360  samples,  a  total  of  four  isolates  were  identified  as Yersinia  species,  including three Y. enterocolitica and one Y. pseudotuberculosis.

Conclusion:  Due  to  the  presence  of  Y.  pseudotuberculosis  and  Y.  enterocolitica  in  raw  milk,  it  is  suggested  that  the  food  and  drug  control  laboratories,  milk  factories  and  other  researchers pay more attention to these bacteria.


raw milk, Yersinia enterocolitica, Yersinia pseudotuberculosis, cow, alkaline