ISOLATION AND MOLECULAR CHARACTERIZATION OF SHIGA TOXIN PRODUCING E. COLI O157:H7 IN RAW MILK USING mPCR

摘要

Raw milk may contain pathogenic microorganisms, probably harmful to humans inclusive of Escherichia coli O157:H7 inflicting hemorrhagic colitis and hemolytic-uremic syndrome. Raw milk is believed to be a high risk food as it is highly nutritious and results in growth and multiplication of different microorganisms. E. coli O157:H7 infect humans by different mode of transmission. Present study was performed to estimate the prevalence and the molecular characterization of E. coli O157:H7 retrieved from retail raw milk samples in Quetta Pakistan. Out of 100 raw milk samples, 12 (12%) possess positive colorless colonies on CT-SMAC. Biochemical tests for the confirmation of E. coli O157:H7 alongside gram’s staining of the colonies had been accomplished. The amplification of isolates by mPCR using universal specific primers, stx1 and stx2 confirmed that 6 (50%), 3 (25%) and 3(25%) were positive for stx1, stx2 and both stx1 and stx2 genes respectively. It is concluded that raw milk harbor E. coli O157:H7, having shiga toxin genes.