To establish a rapid method for detection of Shiga toxin-producing Escherichia coli (STEC) O26∶H11 in ground beef using immonomagnetic separation (IMS) and quantitative real-time PCR.MethodsPrimers and TaqMan probe were designed to amplify fragments for wzx gene of STEC O26. Specificity and sensitivity of the method was evaluated. ResultsThe results obtained from qPCR showed that only STEC O26∶H11was positive , while 23other serovars of Escherichia coli and seven species of bacteria other than Escherichia coli were negative. The detection limit for pure colonies by real-time PCR was 5SymboltB@10^2cfu/ml. After 6h enrichment, samples with the initial STEC O26contamination level of 5×10^2cfu/25g were positive by IMS combined with real-time PCR method. The fluorescence signal of enrichment of samples with the initial STEC O26contamination level of 3×10-1 cfu/25g or above could be detected by both IMS-qPCR and qPCR method after 20h enrichment. IMS-qPCR was more sensitive than qPCR only for the lower initial contamination level after a 6h pre-enrichment time. Chromogenic medium combined with IMS had a higher recovery than chromogenic medium only in isolation of STEC O26. Meanwhile, the recovery of STEC O26∶H11 isolated from CHROMagar medium was higher than that from SMAC medium.ConclusionThe improved IMS-qPCR method for detection of E. coli O26∶H11 in ground beef is highly specific, sensitive, simple and fast. It could be used for fast detect of STEC O26∶H11in ground beef.