IEH utilizes advanced DNA-based methods including ribotyping, macrorestriction fingerprinting using pulsed-field gel electrophoresis (PFGE), and polymerase-chain reaction (PCR) as the basis for an epidemiological tracking system for bacterial source detection.

With respect to molecular techniques in the meat industry, IEH has developed internationally recognized expertise for genotyping and subtyping E. coli O157 and other bacterial pathogens to identify sources of microbial contamination and map their distribution and movement throughout the pre-harvest sector and during the conversion of live animals into meat by obtaining genetic fingerprints of pathogens

By using molecular sub-typing techniques, the likely sources of specific bacterial contamination can be identified. Bacteria can be "DNA-fingerprinted" using the ribotyping or PFGE to distinguish between isolates at the genetic level. Both PFGE and ribotyping offer their own unique strengths depending on what the situation requires. Relying on the different strengths afforded by the two techniques, IEH can differentiate E. coli O157, Listeria spp., Salmonella spp., and lactic acid bacteria.

The advantages of such procedures can help us to:

• track sources of product contamination
• dentify harborage of pathogens on production equipment
• track to suppliers
• link the product to outbreaks
• identify if false positives are due to lab contamination
• eliminate a potential contamination source by showing that isolates from different products or environments are unrelated

As an example, the same bacterial species isolated from different sources within a meat plant will be indistinguishable using standard microbiological techniques, but molecular subtyping may show them to be unrelated at the genetic level. Tracing related isolates through the manufacturing process can help to identify the source(s) of contamination, so that the most effective corrective actions can be taken.