USDA Announces Improved E. coli Test

September 13, 1999

In the wake of one of the country's worst E. coli outbreaks, USDA inspectors have begun using a more sensitive method to detect the often deadly pathogen in raw meat products. The new testing begins immediately in Athens, GA, and will be used in California and Missouri as soon as equipment is in place and operable.

An investigation is being conducted into contaminated well water in Greenwich, NY, in late August that sickened almost 500 people, 51 of whom were hospitalized. A child died from the illness and 10 other children experienced kidney failure.

USDA's Food Safety and Inspection Service conducts E. coli tests on samples collected at federally inspected plants that produce ground beef and at the approximately100,000 retail outlets that grind beef on a regular basis.

The new testing method, called "immunomagnetic separation," will be used in standard procedures in all three FSIS field service laboratories. The method begins after a screening test identifies a potentially positive sample. Antibody-coated magnetic beads recognize and capture E. coli cells in meat product enrichment broths.

A magnetic device captures the beads after they bind to the pathogen. As a result, live E. coli cells are concentrated to facilitate growth and detection on special agar culture media. E. coli then is confirmed by standard FSIS procedures.

Until the laboratories in Alameda, CA, and St. Louis, MO, are equipped properly, all E. coli tests will be conducted at the Athens laboratory.

E. coli can cause serious illness or death when consumed in contaminated foods. Water and a variety of foods can harbor the pathogen. Because consumers may not cook meat thoroughly to kill pathogens that have been introduced below the surface, FSIS has declared that raw ground beef and other non-intact raw beef contaminated with E. coli is adulterated.