Chipotle announced Friday that it will tighten its supplier standards as its E. coli outbreak has already affected over 50 people in the United States.

Chipotle Mexican Grill Inc's stricter standards on its supplier standards risk its promise to only purchase food locally. According to the company's spokesman, Chris Arnold, the company has increased the requirements for all its products suppliers, especially on testing the ingredients. Not all the local suppliers may pass the test, he said.

The Denver-based company started a program in 2008 that supports the local farms, and the tighter standards put this in jeopardy, according to a report by Bloomberg News.

Chipotle markets itself as a company that buys meat and vegetables from local farms within a 350-mile radius of a restaurant chain.

Manufacturing Net reported that the Centers for Disease Control and Prevention said Friday that there are seven more cases of E. coli illnesses in three different states. This raises the total number of affected to 52.

Most of the cases are from Oregon and Washington, but there are also reported cases in Ohio, California, New York, and Minnesota. Forty Seven of the 52 that were affected said they recently ate at Chipotle.

Food Safety News wrote that analysts warn investors that Chipotle Mexican Grill is going to have more volatile days. It dropped again by 6 percent to $574.66 in New York Wednesday.

Now it is off $157.42 per share, a decrease of 21.49 percent after the news of the outbreak was announced. The company closed down 43 stores due to the outbreak.

In November, the company's shares went down 9.5 percent, and 11 percent the previous month. Chipotle closed restaurants in the Pacific Northwest areas, and cleaned them thoroughly.

Before E. Coli, Chipotle restaurants were hit by salmonella and norovirus earlier. The company may only be able to bounce back in its earnings by the fourth quarter in 2016. According to CDC, meat isn't the major source of the outbreak, since vegetarians were also hit.