Risk Factors for Salmonella Contamination of Whole Chicken Carcasses following Changes in U.S. Regulatory Oversight

Abstract

Salmonella is a common cause of foodborne illness in the United States and often is linked to chicken products. Salmonella contamination has been associated with meat processing facility characteristics, such as the number of employees (i.e., hazard analysis critical control point [HACCP]-based definition of size). The risk factors for Salmonella contamination in U.S. poultry have not been evaluated since implementation of the New Poultry Inspection System (NPIS) in 2014. The goal of this study was to determine whether risk factors for Salmonella contamination changed after implementation of the NPIS. Presence or 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 Food Safety and Inspection Service between May 2015 and December 2019. A model was fit using generalized estimating equations for weekly presence or absence of Salmonella, and production volume, geographic location, and season were included as potential covariates among other establishment demographics. Odds ratios (ORs) and 95% confidence intervals (CIs) 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 finished products (OR = 0.498; 95% CI, [0.298, 0.833]) and higher among establishments historically (previous 84 days) noncompliant with HACCP regulations (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 MidEast Central region. These results support continuation of targeted food safety policies and initiatives promoting pathogen reduction by establishments with smaller volumes and those noncompliant with HACCP regulations.