New Sensor Provides First Instant Test For Toxic E. col...( Researchers have developed a sensor t...)

Researchers have developed a sensor that, for the first time, can instantly detect the presence of toxic E. coli bacteria. Contamination by this bacteria is responsible for recent illnesses and deaths in the United States involving fruit drinks and fast-food hamburgers, a massive outburst of food poisoning in Japan, and a current outbreak in Scotland that is linked to 10 deaths.

Raymond Stevens, a chemist at the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley Lab), says the sensors his team have developed are capable of providing an extremely inexpensive, on-the-spot litmus test for E. coli strain 0157:H7. First identified as a threat to humans in 1982, 0157:H7 is the virulent strain of E. coli responsible for these outbreaks.

Says Stevens, "These sensors have been designed so that the presence of the toxin produced by this strain of E. coli causes a color change, from blue to red. The greater the color change in the sensor, the higher the concentration of 0157:H7 toxin. The color change is instantaneous."

Up until now, no technology existed that would allow either food companies, health inspectors, or consumers to determine immediately whether E. coli 0157:H7 is present. Currently, the best detection method requires the taking of a sample which must be cultured for 24 hours. Only then can technicians ascertain whether the bacteria are present (with the use of a variety of tools ranging from microscopes to dyes.) Another detection technique, now under development, relies on polymerase chain reaction technology to multiply the amount of bacterial DNA present in a sample to detectable levels. Several hours must pass, however, before results can be obtained.

The instant analysis provided by Berkeley Lab's new sensors has obvious advantages as a public health tool. Dangerous pathogens can be detected before a food product has been shipped to the store. Another advantage is cost.

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Contact: Jeffery Kahn
jbkahn@lbl.gov
510-643-8285
DOE/Lawrence Berkeley National Laboratory
10-Dec-1996