Process hygiene criteria for Salmonella in pig carcasses: comparing food business operator self-monitoring and official sampling in an Italian high-throughput slaughterhouse

This study compares Salmonella monitoring data obtained from food business operator (FBO) self-monitoring and competent authority (CA) official sampling on pig carcasses in a high-throughput Italian slaughterhouse over ten years (2012-2021 for FBO; 2014-2021 for CA). A total of 1560 FBO and 377 CA samples were analyzed. Salmonella prevalence was 3.46% [95% confidence interval (CI): 2.6-4.5] for FBO and 10.34% (95% CI: 7.3-13.5) for CA, with statistically significant yearly differences in 2015, 2017, 2018, and 2020 (p<0.05). Derby was the predominant serovar (22.6%); however, 20.4% of the FBO isolates were classified only as 'No Typhimurium and Enteritidis', highlighting gaps in serotyping protocols. Discrepancies likely reflect differences in sampling frequencies, carcass origins, and the use of different accredited laboratories by FBO and CA (private and official ones, respectively). The study identifies regulatory ambiguities, including a mistranslation in the Italian Ministerial Note, and recommends enhanced farm-level controls and harmonized surveillance.