Division of Consolidated Laboratory Services

FOOD TESTING

DCLS scientists play large role in making sure our food supply is safe

Whether it is lettuce, peanut butter or some other food that is in the news, we frequently are reminded that food can make us sick. So how do we know the food we are getting at restaurants and grocery stores is ok to eat?

In Virginia, the DGS Division of Consolidated Laboratory Services (DCLS) plays a large role in making sure the food we eat is safe. Along with our state and federal partners, our DCLS scientists monitor the food supply so contaminated items can be removed from the shelves quickly and affected individuals can receive treatment.

Recently, scientists at DCLS identified shiga-toxin producing Escherichia coli, more commonly known as E. coli, in a Virginia apple cider after two citizens filed complaints about getting sick from the product. The testing, done in partnership with the Virginia Department of Agriculture and Consumer Services (VDACS), led the company to recall the unpasteurized apple cider.

"One of our goals at DCLS is to make sure the food that Virginians eat is safe," said Dr. Christopher Waggener, lead scientist of food microbiology and food emergency response at DCLS. "We really want to make sure that the food that is coming from anywhere and everywhere is safe."

Chris WaggenerDCLS partners with VDACS to routinely test food across Virginia. VDACS supplies DCLS with the food samples, and DCLS performs the testing and alerts VDACS of foods that are found to be contaminated. VDACS also supplies DCLS with food samples when an outbreak occurs and when customers file a complaint to VDACS about a certain product.

DCLS also partners with federal agencies, such as the U. S. Department of Agriculture (USDA) and the Food and Drug Administration (FDA) on surveillance programs and testing in preparation of large events, such as national political conventions and sporting events. These partnerships have led to several national food alerts and/or recalls in recent years, including Salmonella and aflatoxin contaminations in foods including peanut butter, cilantro, peppers, tomatoes and alfalfa sprouts.

DCLS serves as the Mid-Atlantic PulseNet Area Laboratory, one of seven the CDC chose to coordinate regional training and laboratory testing response to foodborne outbreaks. Each state has at least one laboratory that participates in the network by populating the PulseNet database with "DNA fingerprints" of foodborne bacteria, such as E. coli, Listeria monocytogenes and Salmonella, isolated from ill patients. Scientists identify the "fingerprint" using a molecular test called Pulsed-Field Gel Electrophoresis (PFGE). Those "fingerprints" are compared at the state level to identify indistinguishable matches, which can suggest a cluster of illnesses or the beginning of an outbreak. Once uploaded into the national database, scientists working in collaboration with state epidemiologists can identify potential multistate or national outbreaks related to the same food.

Each year, PulseNet identifies approximately 1,500 clusters of foodborne disease at the local and state level, about 250 that span multiple states and 10-15 national outbreaks, according to the CDC.

"We are performing more surveillance and using more sensitive and specific techniques to report these instances of food contamination to prevent disease," he said.

DCLS was the first consolidated laboratory in the nation and as such offers a wide variety of unique laboratory testing services in support of public health, environmental protection and emergency response.

"What's unique about DCLS that's different from other laboratories across the country is that we are consolidated," said Waggener. "Typically the agriculture department would have their own labs to do this, but in Virginia we are all in one place at DCLS. So we do approximately 90 percent of foodborne surveillance testing in the state of Virginia here in the DCLS building for all of the state agencies."

DCLS performs more than 7 million tests annually, which includes everything from testing to identify genetic and metabolic disorders in newborn children to the detection of infectious agents and toxic chemicals in humans, animals, the environment, the food we eat and the water we drink. Each year, DCLS trains more than 5,000 scientists, certifies nearly 100 laboratories, receives over 1 million samples, and prepares and distributes more than 300,000 test collection kits across the Commonwealth.

So how does the lab take a common food item like broccoli and find out if it's contaminated?

"We get the sample, we take a little bit of that sample and we put it in a bag with a buffer," said Waggener. "And that buffer works to make what's in that sample happy because we want to try and grow it."

Scientists at the lab use molecular biology techniques like Polymerase Chain Reaction, or PCR, to look quickly for the presence of the DNA of a particular bacteria in a sample. Once they detect the presence of the DNA, they next look for the bacteria in that sample by trying to grow it on media and isolate it. Then they confirm exactly what type of bacteria it is.

It can take a minimum of 24-48 hours to test and find a potential positive using PCR, but Waggener said it generally takes a week or more to confirm the bacteria by growing it on media.

"Food testing and food safety have a direct correlation to public health because we want to make sure the food we eat in the state of Virginia is safe, that's one of our goals at DCLS," said Waggener.

Read more about DCLS's role in keeping the food we eat safe in our Food laboratory Services section on the DGS website.