How to rapidly and sensitively detect for Escherichia coli O157:H7 and Salmonella Typhimurium in cabbage using filtration, DNA concentration, and real-time PCR after short-term enrichment

摘要

It is difficult to detect a small amount of pathogens present in ready-to-eat foods without enriching it. Although enrichment is needed to increase the bacterial population, the time required for this impedes the rapid detection of pathogens. This study was designed to detect Escherichia coli O157:H7 and Salmonella Typhimurium more quickly and sensitively by concentrating bacteria and DNA. Short-term enrichment was used to increase bacterial number and to recovery injured bacteria. Filtration was used to concentrate pathogens and to lower the detection limit. DNA concentration was performed to improve sensitivity by reducing elution volume. Samples were analyzed using real-time PCR. The results showed filtration after enrichment for 2 h allowed the effective detection of E. coli O157:H7 and S. Typhimurium. S. Typhimurium was detected following enrichment for 1 h when DNA concentration was performed. After validation, enrichment for 3 h was shown to be required for detecting E. coli O157:H7 and S. Typhimurium. With DNA concentration, enrichment for 3 h was necessary for the complete detection of E. coli O157:H7, but that for 2 h was needed for S. Typhimurium. The results of this study indicate that this combined method is a rapid and efficient way of detecting pathogens.