Rapid Detection of Shiga Toxin-Producing Escherichia coli by LAMP Real-Time Turbidity Method

Four specific primers were designed for each of the specific sequences of stx1 and stx2 gene of shiga toxin-producing Escherichia coli(STEC). Real-time monitoring of the loop-mediated isothermal amplification(LAMP)reaction was realized with the turbidimeter. Detection could be completed at 63℃ on the real-time turbidimeter in 1 h. The specificity,sensitivity,stability of the method was evaluated,and the method was applied in food detection. The detection limit of the method was 150copies per reaction mixturein optimized condition,and the LAMP amplification results of 4 STEC strains were compliant with their own genetypes separately and 21 non-STEC strains showed no unspecific amplification in the meantime. 68 STEC positive samples was detected in 395 food samples with the positive ratio of 17.2%,the positive ratio oflivestock products was 31.3% which was the highest in all food types,and lower positive ratio were also detected in poultry products,aquatic products andedible raw vegetables. Samples carried stx2 genesignificantly more in positive samples.It suggested that the LAMP real-time turbidity method was rapid,sensitive,high specificity and easy to operate,and could be used as a fast screening method for STEC in food.