Identification of Salmonella Isolated from Dairy Farms in Tehran and Alborz Provinces by Classical and Molecular Methods

Salmonella are endemic on most large intensive dairy farms and salmonellosis is a common cause of neonatal morbidity and mortality. Disease and mortality usually reflect a variety of management events and environmental stressors that contribute to compromised host immunity and increased pathogen exposure.

In this study, PCR method was used to identify Salmonella Enteritidis, Infantis, Dublin and serovars isolated from diarrhea samples and aborted fetuses of Tehran and Alborz provinces dairy Farms. Further observation showed that the isolation of S. Enteritidis and S. Infantis is closely related to the consumption of contaminated poultry meat powder in diet of cows.

Forty-one Salmonella were isolated from diarrhea and aborted fetus samples in Tehran and Alborz provinces Farms and were confirmed by biochemical assays, then the isolates were identified by serological methods by polyvalent and monovalent Salmonella antisera. DNA of samples was extracted by Boiling method and was tested by PCR. Salmonella serovars were identified according to the presence of specificgenes for Salmonella Enteritidis, Infantis and Dublin.  

All samples were tested by PCR were positive. 32 samples were identified as Salmonella Enteritidis (78/04 %), 4 samples were identified as Salmonella Infantis (9/77 %) and 5 samples were identified as Salmonella Dublin (12/19 %).

According to the results, it seems that PCR can be used as a alternative method to the expensive and time consuming biochemical and serological methods for identifying Salmonella serovars. As Salmonella Enteritidis was usually isolated from poultry, isolation from cows may be due to has been used chicken meat powder in diet of the dairy farms.