Abstract: The purpose of this study was to develop a flow cytometry (FCM) method for rapid and quantitative detection of Escherichia coli O157:H7 in milk. E. coli O157:H7 was labeled with fluorescein isothiocyanate (FITC)-conjugated anti-E. coli O157 monocolonal antibodies and then detected by flow cytometry (green fluorescence channel). Serial 10-fold dilutions of E. coli O157:H7 in PBS were tested by FCM method under optimized reaction conditions. The detection range of this method was 2.57 × 103–1.12 × 108 CFU/mL and the sensitivity was 2.57 × 103 CFU/mL. Then the FCM method was applied to artificially contaminated milk samples with 2.31 × 104–1.48 × 108 CFU/mL E. coli O157:H7. The results were consistent with the plate counting method. The sensitivity of our method was 2.31 × 104 CFU/mL and the process required 35 min. This method allowed for rapid, efficient and sensitive detection of E. coli O157:H7 in milk samples. Thus, it has a great potential for application in rapid screening and monitoring of foodborne pathogens.

Key words: flow cytometry, rapid detection, Escherichia coli O157:H7, milk