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Photo: A Salmonella enteritidis colony. Link to photo information
ARS veterinary medical officer Jean Guard has created a faster, less expensive and more accurate test to identify pathogenic strains of Salmonella. Click the image for more information about it.

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New Tracking Tool for Pathogen Investigators

By Rosalie Marion Bliss
June 11, 2015

U.S. Department of Agriculture (USDA) veterinary medical officer Jean Guard has developed a cost-effective diagnostic tool and dataset for identifying various strains of Salmonella. The tool, called Intergenic Sequence Ribotyping, or ISR, is helping improve poultry production and human health internationally, because it helps control Salmonella in the field and in consumer poultry products.

Guard is with the USDA Agricultural Research Service (ARS) Egg Safety and Quality Research Unit at the Richard B. Russell Research Center in Athens, Georgia.

At present, there are other sequence, or DNA-based, methods for serotyping Salmonella. The traditional method, called Kauffmann–White, or KW, is expensive and identifies a particular serotype in only 80 percent of cases, according to Guard. ISR is being used to serotype strains within a particularly virulent group called Salmonella enterica, which is the type associated with foodborne illness.

The ISR technology is available to specialized laboratories, producers or other qualified users who sign a proprietary Material Transfer Agreement (MTA). A producer’s lab technician can take a sample from the farm, amplify for Salmonella, and run a PCR assay to isolate the serotype from a single section or piece of DNA. The producer can then submit that sample to a specialized lab—also an MTA holder—that uses the ISR tool for sequencing the Salmonella. The lab then sends the sequence results back to the producer by entering the sequence into a private online account.

Producers and diagnostic consultants access their private accounts to download their sequences. They then compare their sequences to those in the ISR-based dataset for a perfect match. The ISR technology provides an earlier warning or detection system for farmers.

Read more about this work in the June 2015 issue of AgResearch magazine.

ARS is USDA’s principal intramural scientific research agency, and this research supports the USDA priority of improving food safety.