BACKGROUND: On November 3, 2015, the Alabama Department of Public Health (ADPH) was notified by the Bureau of Clinical Laboratories (BCL) of a cluster of Salmonella I,4 [5],12:i:- with a matching pulsed-field gel electrophoresis (PFGE) pattern of JPXX01.0176 from Tuscaloosa County with isolation dates within the same month. Since 2005 in Alabama, only 493 Salmonella I,4 [5],12:i:- isolates have been identified at our BCL, with only 15 of these isolates matching pattern JPXX01.0176.
METHODS: ADPH administered the National Hypothesis-Generating Questionnaire (NHGQ) as provided by the CDC to all individuals in the cluster. The Bureau of Environmental Sciences (BES) conducted restaurant inspections at two restaurants mentioned in the interviews, obtained supply inventories, and collected food samples. Supply inventories from Sept and Oct were collected for traceback purposes.
RESULTS: Twelve individuals were identified as part of this outbreak. Three (25%) were hospitalized. Ill individuals ranged in age from 3 to 61 years, with a median age of 36 years. NHGQs showed a commonality of consumption of food from two restaurants in the same city. Fifty percent (6/12) had exposure to only Restaurant A, eight percent (1/12) had exposure to only Restaurant B, and seventeen percent (2/12) had exposure to both restaurants. Restaurant A was a dine-in Mexican restaurant while Restaurant B was a chain fast-food Mexican-style restaurant. The NHGQs also indicated a trend of chicken consumption. At Restaurant A, raw chicken and beef were stored on a cold preparation bar next to ready-to-eat items such as guacamole and jalapeño peppers, an opportunity for cross contamination. Three samples were collected: cooked chicken from a steam table, raw chicken from a prep cooler and raw chicken from a walk-in cooler. Enteric testing on all three food samples collected resulted in no isolation of any enteric pathogens.
CONCLUSIONS: This restaurant-associated foodborne outbreak was identified because of an investigation of matching PFGE patterns using NHGQs. Though all restaurants used the same distributor for their chicken supply, it was determined through invoices that they were not the same type of chicken. Also, because the distributor supplies many restaurants statewide, a supply contamination would have resulted in a much larger outbreak. ADPH concluded that the route of transmission was cross contamination of raw chicken and other ready-to-eat foods on the cold foods preparation bar at Restaurant A.