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4 Restaurant Chains That Have Had Salmonella Outbreaks

Chili’s Grill & Bar

In late June of 2003, the Lake County Health Department (LCHD) was contacted by health care providers who had treated patients for Salmonellosis, and customers who had experienced a diarrheal illness after eating at the Vernon Hills, Illinois, Chili’s Grill & Bar. LCHD sent investigators to inspect the restaurant for food safety violations. During the inspection, investigators discovered:

  • The restaurant’s dishwashing machine was broken and corroded; the tube that fed chlorine into the machine was plugged, preventing proper sanitization of dishes. Employees told investigators that the machine had not worked properly for at least a week.
  • Food was not stored at proper temperatures in the cooler.
  • Three employees and a manager had called in sick that day with flu-like symptoms.

LCHD continued to receive reports of Salmonella infection from local hospitals and restaurant patrons throughout the next several days.

During investigating the outbreak, investigators discovered that thirteen employees had been allowed to work despite suffering from diarrhea and other symptoms and learned that Chili’s had operated despite having no water for part of one day, and no hot water for at least one full day. Food safety regulations require that hot water be always available during a restaurant’s operation.

In mid-July, LCHD concluded its investigation, and reported that over 300 individuals had been sickened because of consuming contaminated food at a Chili’s. Of those, 141 customers and 28 employees had tested positive for Salmonella, while 105 other infected individuals met the LCHD’s definition of a probable case. LCHD issued a preliminary report that concluded the outbreak was caused by infected employees who contaminated food with Salmonella because of poor sanitary practices and improper food-handling.


On January 17, 2002, the Boulder County Health Department (BCHD) received a report that two children who had been treated at Avista Medical Center had submitted stool specimens that tested positive for Salmonella. The children, ages one and two, were not from the same home, nor did they attend a common school or daycare.

After interviewing both families, BCHD investigators learned that both infected children had eaten at the KFC located at 255 South Boulder Road in Lafayette, Colorado, 24 hours before the onset of symptoms.

On January 18, BCHD conducted an inspection at the KFC. Two counts of potential cross-contamination were noted: Water used to wet the chicken pieces before battering was left out for nearly three hours at a time, “allowing for bacterial growth,” and the flour mixture used to batter the chicken was used for periods of more than four hours. BCHD’s inspection report noted:

The mixture should only be used for 4 hours. This mixture should be discarded and replaced every four hours…refrigeration of this mixture in between preparation will not maintain the low temperatures needed to suppress bacterial growth.

Additionally, BCHD investigators cited the outlet for poor employee hygiene and “failure to maintain food at proper holding temperatures-hot hold at 140-degrees F.”

Tests conducted on the stool isolates from both infected children by the Colorado Department of Public Heath and Environment confirmed that they were infected with the same strain of the bacteria: Salmonella Newport. Pulsed Field Gel Electrophoresis (PFGE) testing was also conducted by the state. The results of this testing showed that the PFGE patterns of the strain that infected the two children had the same “genetic fingerprint,” indicating that their Salmonella Newport infections came from the same source. As the initial investigation found, the only source that both children had in common was the food they ate that was prepared at the KFC.

Western Sizzlin’

In April of 2002, the Toe River Health District received over 900 telephone calls from individuals who had eaten food at Western Sizzlin’ restaurant in Spruce Pine, North Carolina. A Salmonella outbreak among people who had eaten at the restaurant between April 18 and April 30 resulted in 369 reported illnesses that may have been linked to the outbreak, with 39 lab-confirmed cases of Salmonella infection identified.

Environmental Health (EH) personnel from the Mitchell County Health Department (MCHD) inspected the restaurant, noting deficiencies. The EH team also collected food samples from an individual patron who had taken food home. These specimens were sent to the State Laboratory for Public Health (SLPH) for analysis. The Health Director, EH Supervisor, and Regional EH Supervisor visited the restaurant and asked the manager to voluntarily close the restaurant pending the results of the epidemiological study. EH obtained samples from the restaurant and sent them to SLPH for testing.

Two asymptomatic employees of the restaurant were found to be infected with Salmonella; however, both individuals had eaten food prepared at the restaurant and it could not be determined whether they were infected after eating at the restaurant or one or both of them was the source of the outbreak.

When testing was completed, SLPH reported that leftovers taken home by an individual, including hamburger steak with gravy, fried chicken, and ham, tested positive for the outbreak strain of Salmonella Heidelberg. In addition to food items, an applicator stick marked “gravy” that was taken from the restaurant tested positive. Unfortunately, public health officials were unable to pinpoint the source of the Salmonella outbreak at Western Sizzlin’.


On October 16, 2007, the Minnesota Department of Health (MDH) determined that seven individuals who had submitted stool samples for testing at the State Public Health Laboratory had all been infected with the same strain of Salmonella Typhimurium, suggesting a common source. MDH interviewed all ill individuals and quickly learned that all cases had eaten foods from a Quizno’s restaurant in Rochester, Minnesota in the days before becoming ill. The same day, MDH and Olmstead County Public Health Services (OCPHS) began investigating what appeared to be a Salmonella outbreak.

A case-control study was conducted, with a "case" defined as a person who had eaten at the Rochester Quizno's on or after October 1, 2007 and had Salmonella Typhimurium with an isolate that matched the outbreak strain of Salmonella.

OCPHS conducted an environmental investigation at Quizno’s and sent multiple samples to the MDH lab for testing. The tomato slicer was also disassembled and sent to be swabbed and cultured.

Through its case-control investigation, MDH and OCPHS identified 23 cases; 18 were culture-confirmed, and one person was hospitalized for two days. Four ill individuals were employees of the Quizno’s restaurant. All cases ate food prepared at the restaurant between October 1 and October 8, 2007.

In its final outbreak report, MDH concluded:

This was an outbreak of S. Typhimurium infections associated with consumption of tomatoes at a Quiznos restaurant. The tomatoes were likely already contaminated when they entered the restaurant. Based on case meal dates and produce receipt records, the most likely scenario is that the outbreak was due to second-use tomatoes that entered the restaurant on September 27.

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