In July 2011 a confirmed outbreak of Salmonella Newport infections was associated with eating at two of three restaurants owned and operated by the same family in the Chicago area. The outbreak was first reported to the Chicago Department of Public Health (CDPH) by an emergency department physician who noted an unusual number of patients presenting with complaints of vomiting and diarrhea. Multiple patients reported eating at El Gran Burrito Express prior to their illness. Clinical cultures were performed by area hospital microbiology laboratories. The Illinois Department of Public Health Division of Laboratories serotyped isolates and conducted molecular testing by PFGE. Isolates cultured in outbreak associated patients were serotyped as Salmonella Newport. The PFGE pattern combination was JJPX01.0166/JJPA26.0146. The outbreak was assigned CDC Outbreak ID 1107ILJJP-1.

Thirty-two (32) and 16 probable ill customers were identified. Initially investigators focused on food prepared at El Gran Burrito Express but eventually food prepared at one of the two other restaurants owned by the family was also associated with illness. Seven of 8 food handlers at El Gran Burrito Express tested positive for S. Newport. There were no ill food handlers at the second family-owned restaurant. CDPH attempted to conduct a case-control study but met limited success in identifying controls. The only food items significantly associated with illness were foods containing steak and sour cream. Because the steak is cooked at the time of order, CDPH investigators concluded the likely contaminated food was an uncooked topping such as tomatoes, lettuce, cilantro, onion, jalapeno, etc. Foods collected at the restaurant were negative for Salmonella although leftover taco salad collected from an ill patient of El Gran Burrito Express was positive for the outbreak strain of Salmonella Newport.

Patients with the outbreak strain of S. Newport continued to be identified in the Chicago area after El Gran Burrito Express voluntarily closed because of the outbreak. By November 2011 a total of 209 patients infected with the outbreak strain of S. Newport had been reported in 21 states. Investigation of several restaurant clusters identified tomatoes and jalapenos as possible vehicles. However, traceback efforts by the FDA did not identify a common supplier for either of these items.