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BACKGROUND: Salmonellainfections cause an estimated 1.2 million illnesses and 450 deaths annually in the United States. In August, 2013, a local hospital reported seeing nine patients in their emergency room after attending an Ecuadorian cultural festival.
METHODS: A case was defined as a festival attendee who subsequently developed vomiting and/or diarrhea (≥3 loose stools in a 24-hour period) after eating at the event. Stool specimens were cultured for bacterial pathogens. The hospital laboratory also tested specimens with the Luminex xTAG-Gasterointestinal Pathogen Panel (xTAG-GPP). Festival attendees were interviewed about food consumption and illness history. An environmental health assessment was conducted, and leftover foods from the implicated vendor were cultured.
RESULTS: One hundred nineteen cases were identified, including 40 laboratory-confirmed. Eighty-nine (75%) cases sought care at an urgent care/emergency department, and 11 (9%) were hospitalized. Five Salmonellaserotypes and 10 pulsed-field gel electrophoresis (PFGE) subtypes were identified. At the hospital laboratory, 29 cases were also tested by xTAG-GPP; which identified Salmonella in 4 specimens that tested negative by culture, but failed to identify Salmonellain 7 specimens that were successfully cultured. A single serotype (I 4,[5],12:i:-) accounted for 6 cases that xTAG-GPP failed to detect. Correlation between culture results and xTAG-GPP was 18/29 (62%). A case-control study was not conducted due to the lack of non-ill controls who ate food from the implicated vendor. However, pork (94 cases, 79%), rice (85 cases, 71%), potatoes (82 cases, 69%), and boiled corn (77 cases, 65%) from the vendor were consumed by a majority of cases. Leftover rice, corn, and guinea pig tested positive for 6 Salmonella serotypes and 7 PFGE patterns. No leftover pork, tripe, or potatoes were available for testing. A frozen imported guinea pig collected form the distributor and environmental samples of guinea pig feces collected from the guinea pig breeder’s facility tested negative for Salmonella. An environmental health investigation revealed potential for cross-contamination and time temperature abuse of multiple food items.
CONCLUSIONS: Multiple Salmonella serotypes were isolated from cases and foods. xTAG-GPP provided results more quickly than culture but failed to identify Salmonella in 6 cases of one serotype suggesting, that certain serotypes may be undetected by xTAG-GPP. While the original source of the Salmonella wasn’t identified, two PFGE patterns observed in this investigation had been associated with pork during a prior outbreak, suggesting that cross-contamination from pork or pork tripe to multiple foods was the most plausible source.