Few answers come to light as onion outbreak declared over 

The Food and Drug Administration has closed its investigation and declared the E. coli outbreak tied to McDonald’s Quarter Pounders over, but there are still questions remaining.  

The agency says the most likely source is yellow onions from a Colorado facility operated by Taylor Farms BB #:101575, Salinas, CA, and Taylor Farms subsequently initiated a voluntary recall of its onions from that facility.  

The FDA, Colorado Department of Agriculture, Colorado Department of Public Health and Environment collected product and environmental samples during the investigation, according to the final investigation update published Dec. 3.  

“One FDA sample of recalled onions and on environmental sample from a grower tested positive for E. coli, but they were non-O157:H7 Shiga-toxin producing E. coli (STEC) and did not match the outbreak strain or any other clinical illnesses.”  

No samples collected tested positive for the strain linked to illnesses in the outbreak, but the FDA said “epidemiologic and traceback evidence shows that recalled, yellow onions were the likely source of this outbreak.”  

The investigation didn’t tell us enough to learn from the outbreak, said Frank Yiannas, former deputy commissioner for food policy and response for the FDA, in a LinkedIn post.  

“Without a more transparent accounting of the investigation, and the detailed conditions observed, this will go down as yet another outbreak where a thorough root cause investigation was missed and there were little insights into the actions that could be taken to inform future prevention,” the post said. “We MUST do better at learning from outbreaks if we want to repeat them from happening again.”