"We don't have a positive ID yet on the six new samples," Dr. Ned Calonge, Colorado's acting chief medical officer, said. State health officials are asking labs and hospitals to send samples to the state lab.
But, he added, "we're where we want to be with control of this outbreak."
Eleven of the first 12 cases have been traced to hamburger purchased at Safeway stores, Calonge said.
E. coli is a bacteria that when ingested can grow and cause severe diarrhea, vomiting, intestinal bleeding and kidney failure.
The only confirmed Colorado E. coli death in the past decade was that of a 16-month-old girl who drank contaminated Odwalla fruit juice, said Calonge.
ConAgra meat packers sent the contaminated ground beef to Safeway stores in the metro area, where it was re-ground and repackaged, with "sell-by" dates for June 7-18.
On Thursday, Safeway extended the recall through June 28. While most of the meat already has been eaten, some of it still may be in freezers.
Meanwhile, Rebecca Kruc of Castle Rock said the lab results for her son, who was sickened with E. coli, are looking better. "You just sit and wait. It takes four to six weeks for a person's body to recover from this. You can spend all your time worrying or try to plow ahead."
Two of her sons got sick; one was hospitalized for 11 days. While she was at a doctor's office yesterday, she talked to a woman who had 50 pounds of hamburger in the freezer. "I told her, 'You need to take that back,' " she said.
She called the recall "a joke," because the first few announcements didn't mention Safeway as a place where the contaminated meat might be.
The USDA's announcement mentioned meat packed in 10-pound containers, but didn't mention Safeway, which re-ground and repackaged the meat under its own name.
John Korpal of Douglas County said he bought ground beef at Safeway on June 23. His teen-age son ate some at a barbecue on June 24, then got sick two days later.
They ate the rest of the ground beef on July 1, after the USDA announcement, but before the Safeway announcement.
It wasn't until Thursday, when Safeway extended the recall to June 28, that it covered the date when Korpal bought his hamburger.
"There was a communication breakdown someplace," he said. At the barbecue, it looked like they'd cooked all the pink out of the hamburger, but apparently they hadn't, he said.
Attorney Bruce Clark, who specializes in food-related lawsuits, is representing one of the children who got sick in the outbreak. The child "is doing reasonably well," recovering from a clotting of the blood vessels leading to the kidneys, caused by the body fighting off the E. coli bacteria.
If a retail market such as Safeway re-grinds and repackages contaminated meat from a packer, it is equally liable if a consumer gets sick, Clark said.
Irradiation, or "electronic pasteurization" can kill E. coli at the packing plant, but probably won't become widespread for several more years, Clark predicted.
People don't like the idea of their food going through a radiation process. But families with small children or elderly grandparents probably are ready to pay a little bit more for the assurance.
"In the quick-serve industry, everyone is interested, but looking at the other guy to go first," said Clark.