Dynamic Shifts in Antibiotic Residues and Gut Microbiome Following Tilmicosin Administration to Silkie Chickens

Tilmicosin, an antibiotic widely used in animal husbandry to prevent and treat bacterial infections, raises concerns due to its residual accumulation, which impacts both animal health and food safety. In this study, we conducted a comprehensive analysis of tilmicosin clearance patterns in different tissues, assessed physiological impacts through blood biochemistry, and investigated changes in gut microbial composition with 16S rRNA sequencing of the tilmicosin-treated Silkie chickens. Initially, we observed rapid peaks in tilmicosin residues in all tissues within 1 day after treatment, but complete metabolism took longer, extending beyond 9 days. Moreover, tilmicosin treatment significantly decreased serum levels of total bile acid, blood urea nitrogen, and uric acid, while increasing the levels of direct bilirubin, total bilirubin, and glutathione peroxidase at day 3, followed by a decrease from day 5 onwards. The effects of tilmicosin use on microbial composition and diversity lasted for an extended period, with the relative abundance of Proteobacteria remaining significantly different between the control and tilmicosin-treated groups at 120 days. Additionally, correlation analysis revealed a strong positive correlation between <i>Mucispirillum_schaedleri</i> and tilmicosin residue in all tissues, while <i>Parabbacteroide_distasonis</i>, <i>Faecalibacterium_prausnitzii</i>, and others exhibited negative correlations with tilmicosin residue. Overall, our study indicates a significant correlation between intestinal microbes and antibiotic residues, providing a theoretical basis for guiding the withdrawal period after antibiotic use.