Abstract: Objective To establish a rapid detection system for harmful food-borne microorganisms. Methods In this study，5 kinds of harmful bacteria such as Escherichia coli，Staphylococcus aureus，Shigella，Salmonella，and Listeria monocytogenes were detected. The rapid extraction of genomic DNA in 30 seconds and multiplex PCR were used as experimental techniques. Results 8 pairs of specific primers of the 5 bacteria were screened out，and it was found that Escherichia coli and Listeria monocytogenes could be detected by DNA rapid extraction and PCR. A multiplex PCR system based on DNA rapid extraction of Escherichia coli and Listeria monocytogenes was established. Four pairs of primer combinations：rfbE/Hly，fbE/HlyA1，rfbE/HlyA2，and eaeA/HlyA2，were screened out successfully in multiplex PCR experiments，and the experiments were optimized. Conclusion It is feasible to detect harmful food-borne microorganisms by DNA rapid extraction and multiplex PCR. However，it is necessary to take measures to optimize the experiments. The design of primers for multiplex PCR may be the key to optimize the experiments.

Key words: gastrojejunocolic fistula, anastomotic ulcer, after subtotal gastrectomy