The E. coli outbreak spread to two more states Wednesday, and investigators reported finding contaminated spinach in the refrigerator of one victim.
The outbreak has sickened at least 146 people in 23 states, according to the Centers for Disease Control and Prevention. One person has died and 76 others have been hospitalized, some with kidney failure.
In a break that could help isolate the source of the outbreak, New Mexico's public health laboratory isolated E. coli from an opened package of spinach, the CDC said. Spinach had only been the suspected source of the bacteria, based on interviews with victims.
The package came from the refrigerator of a patient who ate some of the spinach before becoming ill. The New Mexico laboratory completed "DNA fingerprinting" tests late Tuesday, and state and federal officials then matched it to the strain of the bacteria — E. coli O157:H7 — implicated in the outbreak.
That find could help investigators narrow their hunt for the source of the contamination to a specific producer or processor.
Information on the source and brand of the tainted spinach found in New Mexico was not immediately available.
Meanwhile, FDA inspectors began visiting California farms this week, seeking signs of past flooding or cases in which contaminated surface areas had come into contact with crops. They also were looking for potential sources of bacteria inside packing plants.
California produces 74 percent of the nation's fresh spinach crop. The Salinas Valley accounts for roughly three-quarters of the state's share, and it has been the focus of the investigation. The area has links to two of the companies that have recalled fresh spinach products: Natural Selection Foods and River Ranch Fresh Foods.
Also Wednesday, Arizona and Colorado joined the list of states reporting E. coli cases.
The other states are California, Connecticut, Idaho, Illinois, Indiana, Kentucky, Maine, Michigan, Minnesota, Nebraska, New Mexico, Nevada, New York, Ohio, Oregon, Pennsylvania, Utah, Virginia, Washington, Wisconsin and Wyoming. Wisconsin has reported the most cases, as well as the lone death.
Among those sickened, 71 percent were women. Among those victims who could provide a date, they reported falling sick between Aug. 19 and Sept. 5, according to the CDC.
Officials continued to recommend consumers not eat fresh spinach.