Molecular detection of Stx1 and Stx2 genes of E. coli isolated from sub-clinical bovine mastitis in Mosul city

Abstract

Subclinical mastitis in cattle is a pathological condition that causes a financial burden on the dairy industry. In addition, it puts the public sector at risk when pathogens of animal origin are present in unpasteurized milk and dairy products that may enter the human food chain and cause serious illnesses. Our study aimed to determine the percentage of pathogenic Escherichia coli causing subclinical mastitis in dairy cows in Mosul city by confirming the existence of Stx1 and Stx2 genes. Eighty milk samples were obtained from cows suffering from subclinical mastitis using sterile procedures from November 2018 to October 2019. Escherichia coli was isolated, characterized, and confirmed using culture and PCR. According to our research, the pathogenic Escherichia coli in milk samples was 36.3% (29/80). Moreover, molecular screening for a specific Escherichia coli gene revealed that all isolates 100% carried the uidA gene. PCR revealed that 27/29 (93.1%) isolates had both Stx1 + Stx2 genes, and all the isolates 100% possessed the Stx2 gene. No significant relationship was found between the percentage of pathogenic E. coli and the seasons. Even though there were more isolates in the winter than in the summer, this increase was not statistically significant. This study's findings may help pay attention to one of the leading causes of subclinical mastitis, which benefits the private sector in controlling the disease.