Buffered Peptone Water Formulation Does Not Influence Growth of pESI- positive Salmonella enterica Serovar Infantis

Salmonella enterica is a major cause of human foodborne illness and is often attributed to poultry food sources. S. enterica serovar Infantis, specifically those carrying the pESI plasmid, has become a frequently isolated ser-otype from poultry meat samples at processing and has caused numerous recent human infections. In 2016, the USDA-Food Safety and Inspection Service changed the official sampling method for raw poultry products from BPW to using neutralizing BPW (nBPW) as the rinsing agent in order to prevent residual antimicrobial effects from acidifying and oxidizing processing aids. This change was contemporaneous to the emergence of pESI-positive ser. Infantis as a prevalent serovar in poultry, prompting some to question if nBPW could be selecting for this prevalent serovar. We performed two experiments: a comparison of ser. Infantis growth in BPW versus nBPW, and a simulation of regulatory sampling methods. We found that when inoculated into both broths, ser. Infantis initially grows slightly slower in nBPW than in BPW but little difference was seen in abundance after 6 h of growth. Additionally, the use of nBPW to simulate poultry rinse sample and overnight cold shipping to a regulatory lab did not affect the survival or subsequent growth of ser. Infantis in BPW. We concluded that the change in USDA-FSIS methodology to include nBPW in sampling procedures has likely not affected the emer-gence of S. ser. Infantis as a prevalent serovar in chicken and turkey meat product samples.

Automated summary

Salmonella enterica is a common pathogen found in poultry food sources and is a major cause of foodborne illness in humans. The serovar Infantis, particularly those carrying the pESI plasmid, has emerged as a prevalent serovar in poultry meat samples and has caused recent human infections. A change in sampling method by the USDA-FSIS in 2016 to include neutralizing BPW (nBPW) as the rinsing agent raised concerns about the potential influence on the prevalence of ser. Infantis. However, experiments showed that the growth of ser. Infantis in nBPW was slightly slower initially but did not differ significantly from BPW after 6 hours. Furthermore, simulating regulatory sampling methods using nBPW did not affect the survival and growth of ser. Infantis in BPW. Therefore, the change in methodology is unlikely to have affected the emergence of ser. Infantis as a prevalent serovar in poultry meat products.