Journal of Food, Agriculture and Environment

Shigatoxin-producing Escherichia coli in raw cow milk from small farm producers and phylogenetic subtype determination

Author(s):

Ivo Sirakov, Ralitsa Popova, Hristo Daskalov *, Iskra Slavcheva, Eva Gyurova, Boyko Mitov

Recieved Date: 2014-04-30, Accepted Date: 2014-09-10

Abstract:

Cases of unauthorised direct sale of raw cow milk from small farms do exist in Bulgaria. In 2012, we tested 80 samples of raw cow’s milk from small farms in south-western Bulgaria for the presence of shigatoxin-producing Escherichia coli strains. Twenty-three of these samples were taken from cows with subclinical mastitis. The tests included isolation on selective solid medium, biochemical detection and conventional PCR for detection of the shigatoxin genes (stx1, stx2), the intimin gene (eae) and the enterohemolysin gene (hlyA). The stx1 gene was detected in three Escherichia coli isolates from three cow’s milk samples from animals with subclinical mastitis. An Escherichia coli strain with the intimin eae gene was isolated from a sample of normal cow’s milk from a small farm. Two of the isolates with the stx1 gene were also found to harbour the enterohemolysin hlyA gene. The presence of virulence factors in the four Escherichia coli isolates was additionally validated using Real-time PCR. The amplified virulence genes were sequenced and a phylogenetic analysis based on amino acid sequences was performed. The cytotoxic effects of the E. coli isolates were studied on Vero cells. The potential role of shigatoxin-producing E.coli strains for provoking food-borne illness is discussed.

Keywords:

Escherichia coli, raw cow milk, mastitis milk, PCR, virulence factors

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Journal: Journal of Food, Agriculture and Environment
Year: 2014
Volume: 12
Issue: 3&4
Category: Food and Health
Pages: 108-114

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