"This year we evaluated selective enrichment broth for its suitability to recover pathogens from inoculated ready-to-eat meat samples."

Multipathogen screening using immunomicroarry

Investigator: Arun K. Bhunia (Department of Food Science)

Project Report 2006 - 2007

» Download Project Report 2006 - 2007

Project Rationale

Antibody-based methods are widely regarded as rapid and efficient for detecting pathogenic foodborne bacteria. Application of conventional ELISA-based assays and further adaptation in modern biosensor tools show promise for rapid detection. Most assays are developed for detection of a single target pathogen or toxin. As a result, these methods can be very expensive when testing for multiple pathogens because separate assay methods are required. In addition, large laboratory space is required to perform separate tests for each target pathogen, and separate enrichment reagents and procedures are needed for each pathogen detection method. The development of a single test capable of detecting multiple pathogens, enriched in a single enrichment broth, will reduce costs and provide needed results in a short period of time. This technology would benefit regulatory agencies and the food industry when evaluating food products for key food pathogens.

In the last decade, several rapid detection methods-such as antibody-based, nucleic acid-based, and biochemical-based-have been developed. Even though these methods have shortened analysis times, there is still a time requirement to use selective enrichment of samples prior to using conventional rapid detection methods. Antibody-based methods, such as ELISA, require a minimum of 106 CFU/ml for cell detection. To achieve that cell level, it is important to use proper enrichment media.

Project Objectives

  • Develop a microarray assay in 96-well plate and glass slide using a sandwich immunoassay for Salmonella spp., E. coli O157:H7 and L. monocytogenes.
  • Optimize growth and enrichment of these pathogens (healthy or stressed) spiked into model food samples.
  • Evaluate performance of the Pathogen Enrichment Device (PED).

Project Highlights

For simultaneous growth and detection of Salmonella spp., E. coli O157:H7 and L. monocytogenes, our laboratory formulated a selective enrichment broth SEL (Salmonella, E. coli O157:H7, and Listeria). This year we evaluated SEL for its suitability to recover pathogens from inoculated ready-to-eat meat samples (deli turkey and salami). We were impressed with the overall performance of SEL. When SEL performance was compared with the Universal Pre-enrichment Broth (UPB, a commercial multiplex medium), SEL performance was comparable. However, SEL was also able to inhibit the growth of food-associated spoilage or natural contaminants while UPB failed. These results indicate that SEL has the potential to be used as a single selective enrichment medium for multiple target pathogens.