Federal health officials have recalled another 53,200 pounds of ground beef as they try to contain an outbreak of a hard-to-identify form of E. coli, bringing the two day total to 166,200 pounds.

Grant Park Packing from Illinois issued the alert in conjunction with the U.S. Department of Agriculture late Tuesday. And as with the April 23 recall, there’s concern among officials that the beef was shipped to restaurants around the country and could be served to customers.

The affected products were shipped in 40 lb. cardboard boxes marked “For institutional use only” and produced on Oct. 30-31 and Nov. 1 of last year. Meat impacted by the recall has the establishment number “EST. 21781” inside the USDA mark of inspection. These meat was shipped to Minnesota for further distribution and Kentucky for institutional use.

This particular strain of E. coli is harder to identify than others. Food safety officials, working in conjunction with the Centers for Disease Control and Prevention and the Tennessee Department of Health are investigating an outbreak of the strain, with many patients reporting recent meals in restaurants. Beef collected from those restaurants was infected with the same strain, but authorities haven’t definitively linked the two.

People infected with the strain develop symptoms including diarrhea (often bloody) and vomiting. Most recover within a week, but it can lead to kidney failure.

It’s the latest recall for ground beef producers. Earlier this month, 21 tons were recalled JBS Plainwell, after reports it could contain hard plastic. And In March, Washington Beef had to recall 30,000 pounds after learning of a possible contamination.

There have been several problems over the past year. Last October, JBS Tolleson recalled 6.5 million pounds of ground beef, then was forced to recall another 5.1 million pounds in December.

Meanwhile, the first lawsuit has been filed over the recall, with a Kentucky woman suing K2D Foods, saying the tainted meat caused her to become sick and eventually forced her to be admitted to the hospital as her kidneys began to fail.