Temporal Dynamics of Salmonella enterica Serovars in Foods of Animal Origin in Bulgaria, 2007-2023.

Salmonella remains a major foodborne zoonotic hazard, yet long-term data on the distribution of serovars in foods of animal origin in south-eastern Europe are limited. This study describes the temporal dynamics and food-category distribution of Salmonella enterica serovars isolated from foods of animal origin in Bulgaria between 2007 and 2023. A total of 1,906 confirmed Salmonella isolates submitted by public and private laboratories to the National Reference Laboratory were analysed by classical biochemical identification and serotyping according to the White-Kauffmann-Le Minor scheme. Salmonella was most frequently recovered from poultry meat (39.8%), poultry by-products (13.1%), meat preparations (16.9%), minced meat (11.7%) and pork meat (6.9%). Temporal serovar composition differed significantly (Monte Carlo χ2 = 763.0, P < 0.0001; Cramer's V = 0.258). Binomial generalized linear models showed a significant annual increase in S. Infantis (OR/year = 1.095, 95% CI 1.056-1.136; FDR q < 0.001) and decrease in S. Typhimurium (OR/year = 0.929, 95% CI 0.873-0.989; q = 0.030), whereas S. Enteritidis showed no significant linear trend. Food category and major serovar were strongly associated (Monte Carlo χ2 = 827.0, P < 0.0001; Cramer's V = 0.339). S. Infantis, S. Enteritidis and S. Kottbus were concentrated in poultry-derived products, whereas S. Typhimurium, its monophasic variant and S. Derby were associated with pork, minced meat and meat preparations. These findings support continuous serovar-level surveillance and targeted control measures in poultry and pork chains.