Simultaneous enrichment and optical detection of low levels of stressed Escherichia coli O157:H7 in food matrices

Aims: Rapid detection of enterohaemorrhagic E. coli O157:H7 in large range of stress conditions occurring in food processing.

Methods and results: Detection of E. coli O157:H7 in various food processing stress conditions using surface plasmon resonance imaging (SPRi) technique on an antibody microarray was evaluated. The direct detection method based on the culture/capture/measure (CCM) process consists of detecting bacteria during an enrichment step, which significantly decreases the overall assay duration. In optimized culture conditions, this method allows the specific detection of low CFU ml(-1) in <7 h. Detection of bacteria directly in contaminated food samples was also conducted.

Conclusions: The CCM technique using an antibody microarray is a label-free immunoassay that allows rapid detection of E. coli O157:H7 in both food processing stress conditions and complex food matrices.

Significance and impact of the study: The assay is promising for detecting E. coli O157:H7 at different steps of food and drink processing and during storage. SPRi appears to be a suitable and powerful detection method for routine quality controls in food industry with important economic and societal impact.