The Philadelphia Department of Public Health is investigating 14 confirmed cases of Shiga-toxin producing E. coli (STEC) reported since Aug. 30.

The case patients’ ages range from 7 years old to 90 years, the department said, and all presented signs of acute gastroenteritis with bloody and non-bloody diarrhea.

“Case investigation is ongoing but thus far has identified a few shared restaurant exposures,” the department said in a public health alert. “Ongoing case identification is essential to better identify exposure risks, ensure appropriate clinical management and implement prevention strategies.”

The agency did not name the restaurants, and the source of the infections remains under investigation. Exposure to E. coli can occur through contaminated food or water. Outbreaks have been associated with undercooked beef, unpasteurized milk and juice, raw leafy vegetables and petting zoos.

The department is urging providers to test for Shiga toxin and E. coli O157 in all patients presenting signs of acute “community onset” gastroenteritis. STEC is one of five types of E. coli that causes diarrhea with hemorrhagic colitis. Hemolytic uremic syndrome (HUS) is a severe complication of STEC enteritis that can result in kidney failure, seizures and death. HUS risk is highest in children ages 1 to 4 years, the elderly and individuals with compromised immune function.