Surveillance of Enterobacteriaceae, Escherichia coli, and STEC in food from the Piedmont Region (Italy): results of official control activities (2022–2024)

Enterobacteriaceae represent a large family of Gram-negative bacteria including both commensal and pathogenic species such as Escherichia coli, Salmonella spp., and Shigella spp. Among these, E. coli is a common inhabitant of the intestinal tract of humans and warm-blooded animals. However, specific strains such as Shiga toxin-producing E. coli (STEC) are recognized as major foodborne pathogens responsible for severe illnesses, such as haemolytic uremic syndrome. Contaminated foods, particularly raw or undercooked meat and dairy products, as well as vegetables irrigated with contaminated water, represent the main sources of human infection. This study analyses data from official food control activities conducted in the Piedmont Region (northwestern Italy) between 2022 and 2024. A total of 3,370 food samples were analysed, yielding 3,769 microbiological tests performed at the Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta for the enumeration of Enterobacteriaceae, β-glucuronidase-positive E. coli and for the detection of STEC. Overall, Enterobacteriaceae showed the highest prevalence, followed by E. coli and STEC. A bimodal seasonal pattern was observed, with peaks in August and December. Higher positivity rates were associated with samples collected at the production stage compared with retail. Butter and cream showed the highest risk, while curdled milk/yogurt and ready-to-eat foods showed elevated non-compliance in descriptive analyses. These findings highlight the combined role of production-stage factors, food matrix characteristics, and seasonal dynamics in shaping microbiological risk. The results support the importance of risk-based control strategies, with targeted interventions in high-risk sectors and during critical periods, in line with the EU farm-to-fork approach.