Preparing Samples to Detect Foodborne Pathogens

SOUTH EASTON, Mass. —Since the Jack-in-the-Box outbreak in 1993, food contamination continues to dominate the headlines. On June 28th, a Colorado meat company agreed to expand a recall of beef due to possible contamination with the bacteria E. coli 0157.H7. Both the company and the US Department of Agriculture (USDA) said that the beef may be linked to illness in at least eighteen people.

Recently, a Chicago meatpacker was forced to recall 6,152 pounds of ground beef products that may also have been contaminated with E. coli O157:H7. In addition, a Portland, Oregon meat distributor had to recall 39,973 pounds of ground beef products that also appeared to be contaminated with the same type of bacteria.

Food contamination cases aren't limited to meat and poultry, either. FDA inspectors "visiting" facilities as part of a follow-up audit on last spring's widespread pistachio recall (due to the presence of the disease-causing bacteria Salmonella), discovered the possibility that contaminated nuts may have been repacked and distributed to airports and hotels. And on June 19th, Nestle USA announced that it was voluntarily recalling its Toll House refrigerated cookie dough products after a number of people became sick after eating the raw dough.

Since the Nestle cookie dough story broke, CNN has reported that twenty-five people have been hospitalized, and seven have developed hemolytic uremic syndrome, a type of kidney failure associated with E. coli O157:H7. Federal microbiologists are sorting through Nestle's Danville, Virginia plant, which produces the refrigerated cookie dough, to begin the detective work necessary to find the source of the potentially deadly strain of the bacterium.

"The key here is the phrase "detective work," says leading expert in high pressure bioscience and biotechnology, Dr. Edmund Ting, Senior VP of South Easton, MA-based Pressure BioSciences, Inc., who has spent years researching the effects of high hydrostatic pressure on pathogens that contaminate the food supply, such as E. coli, Listeria, and Salmonella. Dr. Ting believes that improvements in food safety depend on the rapid and accurate detection of food-borne pathogens, both in pre-release quality control testing and in post-outbreak investigations. Such detection depends to a great extent on the quality of the extraction of the DNA, RNA, and proteins ("biomolecules") from the pathogens contaminating the food.

Current extraction methods rely principally on heat, electrical charge, sonication, homogenation, and chemical partitioning, explains Dr. Ting. New sample preparation technologies continue to be developed, enabling scientists to extract biomolecules related to food-borne pathogens quickly, accurately, and efficiently. One example cited by Dr. Ting, pressure cycling technology (PCT), employs cycles of hydrostatic pressure between ambient and ultra-high levels (up to 35,000 psi and greater) to safely, reproducibly, and efficiently release DNA, RNA, and proteins from food, plant, and biological samples within minutes, allowing for more rapid and accurate downstream testing.

For more information, visit www.irgnews.com/coi/PBIO