Staphyloicoccus aureus (S. aureus) was found inside a Chicago-area cake bakery and in the topping used to finish its cakes, the U.S. Food and Drug Administration said in a recently released June 1 warning letter.

Rolfs Patisserie of Lincolnwood, IL. was implicated in an outbreak last December that sickened some 100 people. Many of those who became ill had reported eating desserts at catered holiday parties and at a restaurant. Three of the events had been held in Illinois. Seventy illnesses were reported following a single event in Wisconsin.

In connection to that outbreak, Rolf’s Patisserie, which advertises as “a gourmet European Style Bakery” with cakes, pastries, pies and tarts, recalled all its products, including gingerbread houses sold through Whole Markets in 22 states.

Rolfs, which employs about 134. temporarily shut down its operations during the outbreak investigation to sanitize the bakery.

According to the FDA warning letter, S. aureus contamination was found inside the company’s 20,000 square-foot facility. FDA inspected the bakery last Dec. 23 through Feb. 23, taking multiple environmental samples, including those that returned positive for the staph. In the topping material, FDA “confirmed the presence of multiple enterotoxigenic (toxin-producing) strains of s. aureus.”

The warning letter alleges that Rolf’s failed to clean and sanitize equipment in a manner that would protect against contamination of food and food-contact surfaces.

“The diversity and widespread nature of contamination in your facility, including repeat findings from food contact surfaces even after those surfaces were cleaned and sanitized on December 27, 2010 and January 10, 2011, indicates that your cleaning and sanitation operations were ineffective, and that your firm has been operating under insanitary conditions which may reasonably cause contamination of food with this organism, and which may lead to toxin formation,” the warning letter states.

Rolf’s management replied to the inspection report on April 12, promising more frequent cleaning, but FDA found the bakery’s response to inadequate, saying it did not deal with effectiveness of the cleaning and sanitizing operation.

FDA also charged that foods that can support the rapid growth of undesirable microorganisms — particularly cream-filled pastries — were being held too long at unsafe temperatures.

“Exposure to temperatures favorable for S. aureus growth for sufficient time can allow for enterotoxin production,” FDA wrote.  “Accordingly, processing/storage temperature and time exposures are critical for reducing the risk of foodborne illness due to S. aureus enterotoxin. Foods, such as cream-filled pastries, that require considerable handling during preparation and that are kept at slightly elevated temperatures after preparation (over 45°F but below 140°F) are frequently involved in staphylococcal food poisoning.”

FDA’s Chicago district office asked the bakery to reply to the warning letter within 15 days with documentation on how it will correct the violations.