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.