
Field Studies Begin on New, Improved Tests
to Identify Major Bacterial Food PathogensBy Linda
McGraw February 4, 1999WASHINGTON, Feb. 4--A U.S. Department
of Agriculture scientist who has developed faster and more reliable tests
to identify major bacterial food pathogens is now using these tests in
large-scale field studies to show that theyll work on live animals. Irene V. Wesley, a microbiologist with USDAs
Agricultural Research Service in Ames,
Iowa, developed several tests to identify bacteria that may cause human
illness. These tests use a gene multiplying technique called polymerase chain
reaction (PCR) to recognize the pathogens in animal, human and food samples in
less than eight hours. Current culturing techniques can take up to two weeks.
Every year, 6.5 to 33 million people in the United States come down with
foodborne illnesses. The estimated medical costs and productivity losses from
these illnesses range from $6 to $34 billion. Added to the tragic human toll, the food industry loses money and
product reputation through embargoes, recalls, and voluntary destruction of
products, says Floyd P. Horn, ARS administrator. Expanding research
to identify major bacterial pathogens is an important element of President
Clintons National Food
Safety Initiative--a commitment to improving food safety all the way from
the farm to the table. Wesley is based at the ARS National
Animal Disease Center in Ames, Iowa. ARS is USDAs chief scientific
research agency. The USDA carries out the Presidents food safety
initiative along with the Food and Drug
Administration, Centers for Disease Control
and Prevention, and the U.S. Environmental
Protection Agency. Campylobacter is a normal inhabitant of livestock and poultry, but in
humans it may cause disease. C. jejuni is one of the most frequent
causes of bacterial food poisoning. Each year, four million C. jejuniinfections occur in humans in the United States, according to the CDC. This
adds up to four times more illness from Campylobacter than from
Salmonella. C. coli--another type of Campylobacter--is often found in pigs
but rarely causes human illness in the United States. C. coli is so
closely related to C. jejuni that it takes highly specific tests to
differentiate between them. Wesleys PCR test is one of the newest ways to
distinguish between them. She and colleagues are currently using the PCR test
to detect Campylobacter, especially C. coli in pigs. In a current project, funded by USDAs
Food Safety and Inspection
Service, researchers with ARS,
Iowa State University, and
North Carolina State University are tracking
the spread of Campylobacter and other bacteria in pigs from the nursery
stage to slaughter. The study, which includes eight farms and two
slaughterhouses, compares two different ways of raising hogs in Iowa and North
Carolina. Results of the study will be used to determine which farm management
practices reduce foodborne pathogens. Another PCR test stands ready to check for the presence of Listeria
monocytogenes. Listeria has been found in a range of food products--dairy,
liquid whole eggs, red meat, poultry, seafood, and vegetables. Identifying
L. monocytogenes quickly is critical to ensure that our nation has the
safest food supply. A more in-depth article on the research appears in the February issue of
Agricultural Research, ARS
monthly magazine. The article is also on the World Wide Web at: http://www.ars.usda.gov/is/AR/archive/feb99/food0299.htm Scientific contact: Irene V. Wesley, ARS National Animal Disease
Center, Ames, Iowa, phone (515) 663-7200, fax (515) 663-7458, e-mail
[email protected] U.S. Department of Agriculture | |