An E. coli outbreak in Chicago remains under investigation as more customers of Carbón Live Fire Mexican Grill have been added to the victim count. Although public health officials would not comment on how many of the patients have required hospitalization, they did reveal the outbreak count more than doubled in size in eight days. “As of Saturday, July 9th, 54 residents have been identified as contracting STEC (Shiga toxin-producing E. coli ) related to this outbreak,” spokesman Matt Smith said Tuesday. Smith said the Chicago Department of Public Health (CDPH) continues to urge anyone who recently ate food from the restaurant at 300 W. 26th St. and became ill to immediately seek medical attention. In the initial July 1 public notice about the outbreak CDPH reported five of 25 people confirmed with infections had symptoms so severe that they were admitted to hospitals. Smith did not respond to questions about whether any employees of the restaurant had been tested for E. coli or whether investigators had collected any samples of food or swabs of food-contact surfaces at the restaurant. He also did not provide the dates of illness onset for any of the outbreak victims. Generally symptoms develop within five to seven days of exposure, according to the Centers for Disease Control and Prevention. In otherwise healthy adults symptoms usually include severe stomach cramps, diarrhea that is often bloody, and vomiting. “Some infections are very mild, but others are severe or even life-threatening,” according to the CDC. “Around 5 percent to 10 percent of those who are diagnosed with STEC infection develop a potentially life-threatening complication known as hemolytic uremic syndrome (HUS). The Carbón Live Fire Mexican Grill on 26th Street remains closed, but a second location at 810 Marshfield was cleared to reopen Saturday, Smith said. “After conducting a thorough inspection of Carbón’s second location on Marshfield, CDPH’s Food Protection Team determined that the restaurant was safe, clean, and able to meet all requirements for a safe reopening.” Smith said. In the department’s July 1 notice about the outbreak, Chicago officials said “the menu items responsible for this outbreak have not yet been identified and the investigation is ongoing. Health officials continue to be onsite at the 300 W. 26th Street location and are also interviewing patients to rule out other possible exposures.” (To sign up for a free subscription to Food Safety News, click here.)