E. coli outbreak hit Chipotle and other chain stores like Costco, Walmart, 7-Eleven and Starbucks in 2015. Listeria, salmonella and food processing defect also became the source of the biggest case food recall in 2015.

Athough it is not technically a food recall, but contaminated food in Chipotle has become a nationwide case. In August, Chipotle norovirus and possible salmonella outbreak sickened more than 60 people in Minnesota and more than 100 people in California's greater Los Angeles area. Afterward, in November, E. coli outbreak in Washington and Oregon enforced Chipotle to close down its 43 restaurants for examination.

The recent case of food contamination in Chipotle restaurant was reported in Boston, Massachusetts last Tuesday. According to CNN report, 80 students from men's basketball team of Boston College got sick after eating at a Chipotle restaurant. Up to now, the Massachusetts Department of Health has been trying to find the cause of contaminated food.

E. coli has been one major source of food recall and food contamination in 2015. One case of E. coli outbreak in Costco chicken rottisserie chicken lead to a bigger case, when U.S. Food and Drugs Administration (FDA) found that diced celery and onion supplied by California farm is the source of the bacteria. The farm also supplied celery to dozen retailers, and makes it one of the big case of food recall in 2015.

Food Safety News reported that according to recent test, FDA has been unable to confirm E. coli is in the diced celery and onion. In the preliminary testing, Montana Public Health Laboratory indicated the presence of E. coli O157:H7 in the sample of diced celery and onion blend from Costco. The recent test have not ruled out the diced celery and onion as a source of the outbreak, because investigators continue to work in identifying the source of contamination.

Beside E. coli and listeria, salmonella also become the source of food recall. Listeria was discovered in Blue Bell Ice Cream, Jeni's Splendid Ice Creams, some organic products and whole food. Salmonella was found in frozen chicken in Barber Foods and in Aspen Foods as well as chicken wings sold in Tyson.

 The Daily Meal reported major cases of mishandling in food processing, and bacteria contaminations also became source of food recall in 2015. In March, Kraft recalled 6.5 million of Macaroni and Cheese boxes after customers found metal in the boxes. A mislabeling of product made Oscar Mayer recalled more than 2 million pounds of its turkey bacon in August.

There are many causes that made major food recall in 2015. Bacteria such as E.coli, salmonella and listeria, as well as mistreatment in food processing are listed as the main causes.