An outbreak of E. coli from tainted ground beef has sickened 177 people in 10 states, the CDC reported Friday – 21 more people than was reported earlier this week.

Since the beginning of March, 21 of the 177 people infected with the strain of Escherichia coli O103 have been hospitalized, the Centers for Disease Control and Prevention said Friday. No deaths have been reported.

"Two companies have recalled ground beef products that were sold to restaurants and institutions because they may be contaminated with E. coli O103," the CDC said Friday. "Investigators continue to trace other sources for ground beef, and more product contaminated with E. coli O103 may be recalled."

This week, K2D Foods recalled about 113,424 pounds of raw ground beef products and Grant Park Packing recalled about 53,200 pounds of ground beef for concerns it may be contaminated with E. coli O103, according to the Department of Agriculture's Food Safety and Inspection Service.

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Kentucky, Tennessee and Georgia have seen the highest number of cases, with 65, 52 and 41, respectively. Tennessee added 11 more cases since the Tuesday numbers and Georgia added eight more cases.

Other affected states have had fewer cases, with Ohio reporting 10; Florida three; Virginia two; and Illinois, Indiana, Minnesota and Mississippi each reporting one case.

"States are investigating additional illnesses that might be a part of this outbreak," the CDC said.

Those sickened have reported eating ground beef at home and in restaurants. At this point, the CDC is not recommending that consumers avoid eating ground beef. But the agency is stressing that consumers and restaurants handle ground beef safely and cook it thoroughly to avoid passing on any illness.

E. coli infections typically occur three to four days after consuming the germ, the CDC says. Severe stomach cramps, diarrhea (often bloody) and vomiting can result after five to seven days.

In severe cases, patients may get hemolytic uremic syndrome, a type of kidney failure. However, no cases of kidney failure have been reported in connection with this outbreak, officials say.

More on the outbreak:

April 24:More than 56 tons of ground beef recalled in E. coli outbreak, now spanning 10 states

April 25:Woman claims E. coli caused kidney failure, seizures in first suit over 56-ton meat recall

Contributing: Mike Snider

Follow Kelly Tyko on Twitter: @KellyTyko