Fighting foodborne pathogens

According to the Centers for Disease Control and Prevention, foodborne pathogens cause an estimated 47.8 million illnesses, 128,000 hospitalizations and 3,000 deaths in the U.S. each year.

“Early detection at the field and processing plant level can prevent cross-contamination of foodborne pathogens,” said Taejo Kim, Mississippi Agricultural and Forestry Experiment Station researcher and assistant research professor in the Department of Food Science, Nutrition and Health Promotion.

Kim has discovered a way to make industry-wide testing of certain foodborne pathogens fast, easy and affordable.

Kim invented one-tube pathogen assay kits for Salmonella, Listeria, E.coli O157:H7 and Vibrio. Salmonella, Listeria and E.coli can be found in all types of foods. Vibrio, bacteria found in seawater, can contaminate seafood.

“The kits are easy, rapid and cost-effective,” said Kim. “They require no analytic instruments and the results are available in 24 hours or less. Additionally, the reliability has demonstrated a very high percent of sensitivity and specificity during validation.”

Kim said the rapid kits culture, separate and detect whole target pathogen cells in a single tube as opposed to DNA or antigen detection, so it is easier to use than other commercial kits currently available on the market.

“It takes an hour to train a technician on how to use the kits,” Kim said.

Taejo Kim, MAFES researcher and Lurdes Siberio-Perez, a graduate student pursuing a doctoral degree, examine the rapid test kit for Salmonella.

Within 24 hours, the results indicate whether or not a pathogen is present. From there, researchers can use multiple tubes to enumerate the pathogen.

“While the current technology can indicate whether or not a pathogen is present, it doesn’t tell you how much of the pathogen is there,” Kim said. “Our kit can be utilized to determine how much of the pathogen is present.”

Kim said his mission is to continue to develop rapid and cost-effective assay kits to assist industry and consumers in improving food safety, quality and marketability.

“For food safety, we introduce rapid and easy-to-use pathogen assay kits and utilize them as tools for rapid end-product on-site testing including environmental samples,” Kim said. “For food quality, we develop and validate novel food processing and good sanitation programs on fresh and frozen food to expand industry capacity and marketability.”

Provisional patents have been filed for the methods, procedures and ingredients for single tube Salmonella, Listeria and E.coli kits.
“I am working on domestic and international utility patents for the Salmonella, Listeria and E.coli kits,” Kim said.

The Vibrio kits, also submitted for patent, were invented under a collaborative research agreement between MSU and the Food and Drug Administration’s Gulf Coast Seafood Laboratory, or GCSL, in Dauphin Island, Alabama.

“Dr. Kim contacted us several years back requesting our support on a proposal for a Mississippi/Alabama Sea Grant to develop and optimize a kit for determining Vibrio vulnificus levels in oysters,” said Angelo Depaola, Jr., lead scientist for seafood microbiology at GCSL. “The grant was funded and we soon expanded the scope of our collaboration to include development of a detection kit for Vibrio parahaemolyticus.”

According to Depaola, recent outbreaks of Vibrio parahaemolyticus, or Vp, associated with shellfish from the Atlantic coast made this a timely endeavor. GCSL was assisting Atlantic coast states with testing of shellfish from implicated growing areas, which provided an opportunity to test the newly developed Vp kit with real-world samples and compare the results to those of other analytical methods currently used in the laboratory. A subsequent proposal to the National Sea Grant Aquaculture Program to optimize and validate the Vp kit was also funded.

“Invention is perhaps the most enjoyable aspect of being a research scientist for FDA, and we have been delighted with the progress of this collaboration,” Depaola said. “Along the way, all researchers involved have contributed ideas and discussions that have improved the assay performance. This greatly increased the ease of use, as well as potential for sample throughput. The result of this collaborative discovery has provided promising detection methods for both Vv and Vp.”

Depaola said a number of shellfish industry representatives expressed interest in developing analytical capability that is not limited due to the cost of equipment and/or lack of experienced personnel.

“The availability of a simple, rapid and low-cost method such as these kits could greatly facilitate the industry and partners in conducting their own testing,” Depaola said. “An inexpensive, high-throughput method also provides the opportunity for more studies to evaluate the best management practices for reducing vibrio risk in shellfish and other seafood products.”

The FDA and MSU are currently planning validation studies required for these methods to be accepted for use in the National Shellfish Sanitation Program.

By Vanessa Beason, Photography by Beth Wynn