Ten-Year Surveillance of Microbiological Non-Compliance in Pork: Associations with Season and Slaughterhouse Scale in Lower Northern Thailand.

Microbiological non-compliance in pork may indicate deficiencies in slaughterhouse hygiene and pathogen control. This retrospective surveillance study evaluated associations of season and slaughterhouse production scale with microbiological non-compliance in 3103 pork samples collected in Lower Northern Thailand during 2015-2024. Samples were assessed using Department of Livestock Development criteria for aerobic plate count (APC), coliforms, Escherichia coli, Enterococcus spp., Staphylococcus aureus, and Salmonella spp. Outcome-specific mixed-effects logistic regression models included calendar year, season, production scale, and province as fixed effects and slaughterhouse as a random intercept. Salmonella spp. was the most frequent non-compliance endpoint (40.90%), followed by APC (36.61%). Compared with winter, the rainy season was associated with higher odds of coliform (adjusted odds ratio [AOR] = 1.75, 95% CI: 1.23-2.50) and Salmonella spp. non-compliance (AOR = 1.51, 95% CI: 1.20-1.91). High-scale slaughterhouses had higher odds of coliform (AOR = 2.61, 95% CI: 1.21-5.64), E. coli (AOR = 2.39, 95% CI: 1.22-4.69), and Salmonella spp. non-compliance (AOR = 2.02, 95% CI: 1.17-3.48) than low-scale facilities. These findings support seasonally targeted, risk-based surveillance and continued direct pathogen testing alongside hygiene indicators.