Real-time reverse transcription PCR detection of viable Shiga toxin-producing Escherichia coli O157:H7 in food.

摘要

Shiga toxin (Stx)-producing Escherichia coli (STEC), particularly E. coli O157:H7, have been associated with food-related outbreaks and have become a global health concern. Detection of low numbers of viable STEC in food is undoubtedly challenging. The present study demonstrated that 7x102 to 7x103 cfu E. coli O157:H7 cells in 50 mL of inoculated food samples including apple juice, lettuce and ground beef could be concentrated through a two-step filtration technique. Bacterial RNA was effectively isolated from the concentrated E. coli O157:H7 cells with the combination of Trizol Max Bacterial RNA Isolation Enhancement Reagent and TriReagentReg.. Real-time reverse transcription polymerase chain reaction with seven sets of primers targeting virulence and serotype genes of E. coli O157:H7 specifically detected the bacterial RNA representing 1x102 to 1x103 cfu viable bacterial cells. The total detection time from sampling to measurement was approximately 4 h. This study provides a rapid and specific detection method for viable STEC in food.