Multidrug-Resistant Salmonella I 4,[5],12:i:− and Salmonella Infantis Infections Linked to Whole Roasted Pigs from a Single Slaughter and Processing Facility

Abstract

We describe two outbreaks of multidrug-resistant (MDR) Salmonella I 4,[5],12:i:- infection, occurring in 2015 to 2016, linked to pork products, including whole roaster pigs sold raw from a single Washington slaughter and processing facility (establishment A). Food histories from 80 ill persons were compared with food histories reported in the FoodNet 2006 to 2007 survey of healthy persons from all 10 U.S. FoodNet sites who reported these exposures in the week before interview. Antimicrobial susceptibility testing and whole genome sequencing were conducted on selected clinical, food, and environmental isolates. During 2015, a total of 192 ill persons were identified from five states; among ill persons with available information, 30 (17%) of 180 were hospitalized, and none died. More ill persons than healthy survey respondents consumed pork (74 versus 43%, P < 0.001). Seventeen (23%) of 73 ill persons for which a response was available reported attending an event where whole roaster pig was served in the 7 days before illness onset. All 25 clinical isolates tested from the 2015 outbreak and a subsequent 2016 smaller outbreak (n = 15) linked to establishment A demonstrated MDR. Whole genome sequencing of clinical, environmental, and food isolates (n = 69) collected in both investigations revealed one clade of highly related isolates, supporting epidemiologic and traceback data that establishment A as the source of both outbreaks. These investigations highlight that whole roaster pigs, an uncommon food vehicle for MDR Salmonella I 4,[5],12:i:- outbreaks, will need further attention from food safety researchers and educators for developing science-based consumer guidelines, specifically with a focus on the preparation process.