The Moscow Times reports that E. coli bacteria has been found in butter at four kindergartens in the city of Samara, following the hospitalization this week of almost 30 children in the neighboring city of Tolyatti from food poisoning, Itar-Tass reported Friday.

The bacteria was discovered during a food safety check initiated after a raft of food-poisoning cases in Tolyatti, which were apparently caused by dairy products, including tvorog and kefir. In total, 37 children under the age of two fell ill, with 28 of them being hospitalized.

A criminal investigation has been opened in connection with the Tolyatti poisonings, with the charge of failing to meet safety standards in work with young children.