EDMONTON, Alberta – Beef steaks sold at a Costco Wholesale store in Edmonton, Alberta, have been linked to several confirmed illnesses caused by E. coli O157:H7, according to the Canadian Food Inspection Agency (CFIA). But health officials said it’s not clear if the steaks were contaminated before or after arriving at the store.

The CFIA issued a health hazard alert warning consumers not to eat Strip Loin Grilling Steak products that were sold from Sept. 4 to Sept. 7 in variable weight packages under the store's Kirkland brand. The agency said the steaks came from meat processed at Edmonton-based XL Foods Inc. The company already is involved in an ongoing recall of ground beef products.

The issue is that Canadian health officials may not be able to pinpoint the source of contamination because the steaks in question were mechanically tenderized. Public health officials said they don't know if the meat was already contaminated when it was shipped to the store, or if a meat tenderizing machine transferred the bacteria to the meat. Costco does not mechanically tenderize all of its steaks.

Provincial health officials asked Costco to stop using meat tenderizing machines because the technique increases the risk of illnesses, according to local news reports. Officials also said they plan to investigate how widespread meat tenderizing is and whether consumers should be advised to cook their steaks longer.

Dr. James Talbot, chief medical officer of health for Alberta, said during a press conference that health officials would determine whether mechanically tenderized products should be labeled or if the practice should be allowed.