Risk Factors for Salmonella Contamination of Whole Chicken Carcasses following Changes in U.S. Regulatory Oversight
Salmonella is a common cause of foodborne illness in the U.S. and often is attributed to chicken products. Previous studies have associated Salmonella contamination with meat processing facility characteristics such as the number of establishment employees (i.e., HACCP size). An evaluation of risk factors for Salmonella contamination in U.S. poultry has not been performed since implementation of the New Poultry Inspection System (NPIS) in 2014. The goal of this study was to determine if risk factors for Salmonella contamination changed following implementation of NPIS. Presence/absence of Salmonella in whole chicken carcasses was modeled using microbiological testing data collected from 203 poultry processing establishments by the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS) between May 2015 and December 2019. A model was fit using generalized estimating equations for weekly presence/absence of Salmonella with production volume, geographic location, and season included as potential covariates, among other establishment demographics. Odds ratios (OR) and 95% confidence intervals (CI) were calculated from the marginal model. Of the 40,497 analyzable samples, 1,725 (4.26%) were positive for Salmonella. Odds of contamination was lower among establishments slaughtering ≥ 10,000,000 birds per year (OR = 0.466; 95% CI: [0.307,0.710]) and establishments producing ready-to-eat (RTE) finished products (OR = 0.498; 95% CI: [0.298,0.833]) while higher among establishments historically (previous 84-days) noncompliant with HACCP (OR = 1.249; 95% CI: [1.071,1.456]). Contamination also significantly varied by season and geographic region, with higher odds of contamination during summer and outside the Mid-East Central region. These results support continuation of targeted food safety policies and initiatives promoting pathogen reduction by smaller-volume establishments and those noncompliant with HACCP regulations.