USDA Announces Development of Device That Detects E.coli
WASHINGTON, Sept. 18, 2001—The U.S. Department of Agriculture announced that a new weapon to detect the most lethal kind of E.coli (strain O157:H7) has recently been developed by a researcher at Michigan State University, with funding provided, in part, by the USDA's Cooperative State Research, Education and Extension Service. Its nickname is "the electronic nose" because it can sniff out different gases in manure and identify those which are emitted by E. coli O157:H7.
"There are many advantages to this new device including its quick results and ease of use," said Colien Hefferan, administrator, Cooperative State Research, Education and Extension Service. "In addition, no laboratory expertise is necessary to perform the test."
The device was developed by Evangelyn Alocilja, assistant professor, Department of Biosystems Engineering at Michigan State University. She built it from seven gas sensors which sniff out gases emitted by bacteria and translate these gases into a series of wavy lines on a computer screen. The O157:H7 strain has bumps appearing on the wavy lines, unlike other E.coli signatures.
E.coli O157:H7 is a potentially deadly bacteria that can cause bloody diarrhea and dehydration. The very young, the elderly, and persons with compromised immune systems are the most susceptible to foodbourne illness.
E.coli O157:H7's favorite hiding place is in those cattle that may have an acid stomach. There it flourishes and is finally shed in the manure. The electronic nose sniffs a manure sample looking for O157:H7's distinctive signature. By catching it at this early stage, the farmer has time to modify the cattle's diet and eliminate the acid conditions that promoted the bacteria's growth.
Besides flourishing in the stomachs of some cattle, the bacteria is also known to infect some fruits and vegetables via contaminated water that was used to irrigate them or from contaminated fertilizer that was applied to make them grow. To detect the bacteria in fruits and vegetables, the sensor would scan samples from truckloads that are bound for market. Results from the scan are almost immediate versus the usual 10-14 day wait to send a sample off to a laboratory for conventional testing.